© National Audit Office 2026

Electronic monitoring: improving resilience to meet increasing demand

Ministry of Justice and
HM Prison and Probation Service

Session 2026-27
10 July 2026
HC 266

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Gareth Davies
Comptroller and Auditor General
National Audit Office

3 July 2026

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The National Audit Office study team consisted of:

Kemi Duroshola, Rachel Nash, Oyeleke Olaoye and Jay Vigneswaralingham, with assistance from Scott McMillan and Alec Steel, under the direction of Jenny George.

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Key fact

Summary

Introduction

1 Electronic monitoring (EM), or ‘tagging’, uses technology to remotely monitor a person’s location and compliance with community orders, court and immigration bail conditions and conditions post release from prison. Potential breaches are reported to relevant agencies for response, including the police, probation and Home Office. The Ministry of Justice (MoJ) holds the contracts for EM services in England and Wales, while HM Prison and Probation Service (HMPPS), an agency of MoJ, is responsible for overseeing the delivery of the service and managing supplier performance. The EM service refers to the supplier-delivered tagging and monitoring contracts, but effective electronic monitoring depends on the wider EM system, which involves courts, prisons, probation and the police. In this report we use the term ‘officials’ to refer to staff across these organisations responsible for managing electronic monitoring and responding to breaches. HMPPS estimates that monitoring a tagged individual costs on average £4,900 per year. This equates to an estimated annual direct cost of £133 million for 2025-26, including costs incurred by probation but excluding wider system costs such as courts and police activity.

2 In October 2023, MoJ awarded new contracts to: Serco, to fit tags and monitor tagged individuals; and Allied Universal Electronic Monitoring (Allied), to supply the tags and monitoring system. This followed the reprocurement of the EM service as part of its 2021–2026 EM expansion programme. The new service went live in May 2024, with a transition period as the new suppliers took over and moved services onto new systems and devices. But by mid-2025, MoJ and HMPPS acknowledged there had been significant performance issues, including long delays in fitting tags.

3 In September 2025, MoJ announced plans to significantly expand EM. This expansion would be part of the Sentencing Act 2026, which aims to ease prison pressures by managing more offenders in the community. It estimated that up to 22,000 additional individuals would be tagged each year from 2027, placing further strain on a system that had already been performing poorly. To boost the system’s ability to cope with increased demand, HMPPS has set out plans to ‘Stabilise, Scale and Transform EM’ (STEM).

4 This report examines whether MoJ and HMPPS have:

clearly defined expectations for EM, including how to measure success (Part One);

understood whether the system is operating in line with expectations and addressed early underperformance (Part Two); and

made plans to ensure EM is resilient to rising demand (Part Three).

5 We assess EM resilience as the capability to maintain critical EM functions at required performance through disruption, adapt to escalating demand, and recover quickly from shocks while protecting public safety. In practice, an efficient and resilient EM system ensures that individuals who are required to be tagged are monitored, that any breaches are identified and acted on in a timely and proportionate way. Also, that there is early identification of risk and appropriate responses to it.

6 This report focuses on EM in the adult criminal justice system. It does not assess immigration or youth justice tagging, evaluate the procurement of the current contracts or provide a full assessment of the delivery of the EM expansion programme.

Key findings

Expanding electronic monitoring

7 HMPPS met its aim to increase the EM population to around 25,000 by 2025, through its 2021 expansion programme. For example, it extended EM to new groups through GPS tagging for certain acquisitive crimes and offenders at risk of committing domestic abuse and rolling out alcohol monitoring for some prison leavers. As a result, the EM population in England and Wales increased significantly from around 13,400 in January 2021 to 28,700 by March 2026 (although changes to definitions mean these two numbers are not directly comparable). Individuals tagged after leaving prison form the largest EM population (37%), followed by those on court bail (34%). This reflects both HMPPS’s expansion initiatives and its efforts to ease prison capacity pressures by making greater use of alternatives to custody (paragraphs 1.5 to 1.6, 2.2 and 3.2, and Figure 4).

Measuring system success

8 There is no shared understanding of what a more responsive EM system should look like or how it should be measured. MoJ’s 2022 EM strategy set out a vision for a robust, innovative and data-driven system. This system would enable officials to respond quickly to breaches (non-compliance with EM conditions) to manage risks effectively in the community. HMPPS set expectations for its main suppliers through contract key performance indicators (KPIs). However, there is no shared definition of what ‘more responsive’ means, including how quickly police or probation officials should act on breaches. This is partly because agencies such as the police sit outside MoJ and HMPPS’s control. Some stakeholders we spoke to had differing expectations of system responsiveness. For example, Serco’s contract does not require it to provide officials with details of an individuals’ breach until 29 to 53 hours after it occurs. Some stakeholders expected breaches to trigger a faster response (paragraphs 1.7 to 1.9, 2.3, 2.18 and 3.6, and Figures 2 and 3).

Current system performance

9 Available data indicate that key aspects of EM are not working as MoJ and HMPPS intended. There are a number of examples which have at times led to backlogs and/or public protection risks:

Early supplier performance meant that individuals were not tagged on time, and officials were not notified of potential breaches in a timely manner, though performance has since improved: There were delays in fitting and removing tags and notifying officials of potential breaches between August 2024 and July 2025. During this period, the backlog of visits to fit, check or remove tags increased significantly to a peak of 7,000 visits in October 2024 from 1,200 in May 2024.

HMPPS does not have an accurate understanding of the number of individuals that should be monitored and are not (‘unmonitored’), but this number could be significant: As of March 2026, HMPPS was reviewing around 8,900 cases of individuals recorded as having an active EM order but no tag (around 24% of those required by courts or other bodies to be tagged), to identify unmonitored cases. Current cases under review include some cases mistakenly left active, but data exclude individuals whose devices have been disconnected for 14 days or more. HMPPS expects to publish statistics on the number of unmonitored individuals in late July 2026.

Probation and police staff report that poor quality information and capacity constraints limit their ability to respond promptly to breaches: The police also raised concerns that breaches of court bail conditions often result in limited consequences when cases return to court but are resource-intensive to respond to. A lack of data on response times and outcomes prevented us from assessing the scale of these issues (paragraphs 2.6 to 2.7, 2.10, 2.12 and 3.14, and Figure 6).

10 Reduced performance targets for Serco during transition arrangements lasted longer than planned. The new EM service did not become fully operational until October 2025, around 11 months later than planned, following delays to system and device changeovers. MoJ and HMPPS set 14 contractual KPIs spanning the range of the service against which to measure Serco’s performance. But it decided to reduce contractual performance targets to a limited set of four KPIs while the suppliers transferred to new systems, recognising the significant change required. These KPIs covered a limited range of activities such as equipment reinstallation and removal, but not some key aspects of service delivery such as timely attempts to fit tags. As a result, Serco was formally assessed against a reduced set of four KPIs for much longer than intended, although HMPPS tracked a wider set of performance metrics alongside this. Early performance was poor, against even these limited KPIs. Between August 2024 and July 2025, performance was often significantly below target for all but one of these KPIs. During this period Serco made changes to its senior leadership, strengthened its performance management and focused on reducing the visits backlog to below HMPPS’s tolerable level of 400 visits (paragraphs 2.6, 2.7 and 2.10, and Figures 6 and 7).

11 HMPPS has used contract levers and worked with suppliers effectively to improve performance. In response to early poor supplier performance, HMPPS strengthened its oversight to improve supplier performance and worked collaboratively with Serco to implement a performance improvement plan. From November 2025, the plan introduced the full set of KPIs, but MoJ and HMPPS agreed a period of gradual improvement against contractual KPI targets until February 2026. Performance against KPI targets improved under this plan, with Serco meeting all contractual targets in March 2026. Allied delivered most of its original contractual requirements on time, including those required to meet the key transition milestone. It met its two KPIs for just over half of the months between August 2024 and April 2026, with a dip in system availability in late 2025 during the delayed system changeover period. HMPPS explained that it had charged suppliers the maximum amounts permitted under the contracts for the performance level recorded from Serco for poor performance and transition delays, and from Allied for poor performance (paragraphs 2.8 and 2.10, and Figure 7).

12 Some KPI metrics and wider data weaknesses limit visibility of whole system performance. For example, Serco’s tag-fitting KPI measures whether it has made two attempts to tag an individual within the required time period for 95% of cases, not whether those attempts are successful at fitting a tag. In February 2026, although Serco met its 95% timeliness target for tag-fitting visits, it was only successful in fitting a tag for 62% of the individuals it visited after those two attempts. Unsuccessful visits can result from factors both within and outside of Serco’s control, including individuals not being at the address at the time of the visit or refusing to be tagged. MoJ and HMPPS also lack insight of performance related to breaches, including whether police and probation respond, how quickly or what outcomes follow. HMPPS has made some improvements to its data, but data quality issues persist. These issues limit HMPPS’s understanding of performance, increase workload elsewhere and make it harder to identify key risks, including the scale and impact of unmonitored individuals (paragraphs 2.3 to 2.5, 2.11, 2.13 to 2.14 and 2.16, and Figure 5).

Efforts to improve the system

13 HMPPS and wider stakeholders have sought to improve performance, but major inefficiencies remain. HMPPS is piloting new processes, such as tagging offenders before releasing them from prison, alongside developing EM digital and data systems to complement supplier systems, supporting a more efficient, data-driven service. Both MoJ and Serco have commissioned reviews to identify problems. However, inefficiencies persist across the system:

high error rates in EM orders from agencies to Serco delay tagging and require rework. HMPPS’s new order system still had error rates of around 21% as at May 2026.

low tagging visit success rates waste resources and leave individuals untagged. Only 45% of individuals were successfully tagged within the standard number of attempts in 2025. This proportion was 62% for January to April 2026.

high volumes of alerts and breach notifications, and a lack of risk-based prioritisation require significant staff time without always generating value: Staff must review all tag alerts, and a review found that only 10–50% of alerts result in breach notifications being sent to officials, and where outcomes are recorded nearly half result in ‘no further action’. On visits, we observed that both serious and minor breaches were treated in the same way regardless of severity.

a low device collection rate reduces available stock. Only around 60% of tagging equipment is collected from individuals after an EM order ends (paragraphs 1.8, 2.15 to 2.16, 2.18 and 3.5, and Figures 8, 12 and 13).

14 Over-optimistic timescales, weak transition planning and unclear system ownership have allowed inefficiencies to persist. HMPPS’s and Serco’s efforts to resolve transition issues and backlogs delayed planned productivity improvements, including automated scheduling for field visits and the rollout of a new EM order system. Transition issues arose due to both Serco underestimating the complexity of the system and weaknesses in HMPPS’s approach, including unclear requirements, limited contingency planning and weaknesses in systems assurance and testing. Limited user involvement in some areas of system and process design also led to some solutions not meeting all staff needs. The lack of a system-wide owner for EM, and limited data on where problems lie have further slowed the resolution of cross-organisational issues (paragraphs 2.9, 2.15, 2.17 to 2.19 and 3.6).

EM outcomes in reducing reoffending

15 MoJ and HMPPS have improved the evidence base on the effectiveness of EM in reducing reoffending, but some gaps remain. MoJ and HMPPS have carried out three impact evaluations on EM. These show some promising results of EM reducing reoffending while individuals are tagged. The findings include reductions in reoffending for those wearing radio frequency tags and efficiencies for the police through schemes to tag those convicted of acquisitive crimes such as theft. However, gaps remain in understanding effectiveness after the tag is removed, and across different EM groups. Without clarity on which groups benefit most from EM and how effectiveness varies, MoJ lacks a strong basis for prioritising or targeting EM if capacity becomes constrained (paragraphs 2.20 to 2.21).

Readiness to respond to increasing demand

16 To address higher demand from the Sentencing Act (the Act), HMPPS plans to strengthen EM resilience through STEM plans agreed in October 2025. The expansion of EM is key to the government’s response to address the prison capacity crisis. In September 2025, prior to implementation of the Act, MoJ estimated that up to 22,000 additional people may need to be tagged per year. It expected the largest growth in those leaving prison (around 13,000 additional individuals) and court bail cases (around 8,000 additional individuals). MoJ had not updated its modelling as at June 2026, but early estimates indicated that expected increases remained broadly consistent with September 2025 figures. However, both projections are subject to several uncertainties. Through its STEM plans, HMPPS aims to stabilise the service, build the foundations needed to scale up activity and transform service delivery through new technology and data. To support its transformation aims, it is developing a series of innovations and pilots. For example, it plans to strengthen management of domestic abuse offenders through tags that could monitor their proximity to their victim. It also plans to improve access to EM data for probation officers. The government has allocated up to £175 million to fund the expansion over the 2026–2029 spending review period (paragraphs 3.2 to 3.6, and Figures 9 and 12).

17 HMPPS is continuing to expand the EM service, while key elements are not yet working effectively, meaning the service is operating beyond its stated risk appetite. HMPPS has strengthened risk management for parts of the EM system within its direct control and has set its risk appetite across 13 categories, including a ‘cautious’ appetite on operational risk. However, the service has been operating outside its risk appetite and tolerance levels in several areas, with independent reviews identifying significant weaknesses in tagging orders and breach processes. HMPPS aims to address these issues through the ‘stabilise’ and ‘scale’ workstreams of its STEM plans. But it will not have completed all the actions within the ‘stabilise’ workstream before demand increases. In April 2026, HMPPS identified a significant risk that EM processes and training may not be ready in time to support the implementation of the earned progression model and associated changes. Under the model, due to be introduced from September 2026, individuals will be released from prison earlier, on the presumption they will then be tagged. Expanding a service while key elements are not yet working effectively increases the risk that performance or threats to public protection may worsen. As of May 2026, MoJ and HMPPS had made key design decisions and HMPPS had implemented a range of actions that it considers has reduced the risk (paragraphs 3.3 to 3.4 and 3.12 to 3.13, and Figures 10 and 11).

18 MoJ, HMPPS and partners do not yet have a robust system-wide approach to manging risks as the Act is implemented. MoJ, HMPPS and partners have undertaken some recent cross-system work to identify and manage risks. But they have not yet got a robust system-wide approach to monitoring risks to public protection, such as a comprehensive set of measures to monitor risks and clear thresholds for escalation. While MoJ has developed modelling for parts of the system, we did not see a sufficiently joined-up, system-wide view integrating capacity across courts, policing, probation and suppliers. As a result, MoJ, HMPPS and partners lack a comprehensive view of where capacity constraints lie in the system. Significant understaffing persists, including an estimated shortfall of around 2,200 full-time equivalent (FTE) probation staff as at March 2026, which HMPPS expects to reduce to around 1,500 FTE by September 2026. MoJ also estimates that the police will need to respond to an additional 4,200 bail breaches per year that result in custody, including some relating to EM. The National Police Chiefs’ Council estimated that increases due to EM will cost around £20 million annually, but the police explained forces have received no additional funding and will need to balance this activity with other competing priorities (paragraphs 3.8 to 3.11 and 3.14).

19 There are current and future risks to the resilience of the EM delivery model:

Serco’s need to make efficiencies in the current contract risk exacerbating operational pressures. From the outset Serco planned to achieve efficiencies to reduce its operational service costs, including by increasing the proportion of single-officer visits, almost halving its field workforce. However, delays to service migration, some of which were outside its control, have prevented Serco from implementing these efficiencies as planned. This creates a trade-off. While reducing workforce capacity ahead of increases in demand could increase the risk of backlogs, retaining additional capacity to manage these risks creates financial pressures for Serco. As at June 2026, MoJ had agreed up to £48 million of additional payments to Serco over the contract life. This includes up to £6 million to retain staff to help manage spikes in demand as the Act is implemented. These payments cover the cost of some delays outside of Serco’s control and some activities Serco undertook that were not covered by the contract. As at March 2026, £10 million has been paid to Serco.

Increasing pressures risk diverting focus from HMPPS’s ongoing planning for future delivery models when current contracts expire in 2030. HMPPS aims to plan the future model through its STEM plans and has begun initial stakeholder engagement. However, there is a risk that the need to address increasing pressures may divert focus from ongoing plans (paragraph 3.15).

Conclusion

20 EM is a central component of the government’s plans to manage pressures on prisons. Since 2021, HMPPS has successfully and rapidly expanded EM to new groups. However, overall EM is not working as intended, creating public protection risks. HMPPS has worked with Serco to reduce backlogs in fitting tags, but supplier performance improvements alone are not sufficient to provide confidence that the system is resilient or protects the public. Significant inefficiencies persist across the system, wasting staff time and taxpayers’ money, and limiting performance improvements. Of particular concern is the likely significant number of unmonitored individuals. Additionally, police and probation officers often lack relevant information or capacity to respond to breaches quickly, and governance is fragmented. Overall, we conclude that MoJ and HMPPS have therefore not yet achieved some key aspects of their 2022 vision of a data-driven, robust and responsive service.

21 Demand for EM is expected to rise substantially from September 2026. HMPPS has set out its plans to stabilise, scale and transform the service. However, stakeholders do not yet have a joined-up understanding of system-wide capacity or risks. Expanding a system that is not yet working as intended heightens risks to future performance and, ultimately, to public protection. We judge that further expansion of the EM system will not be effective or efficient unless MoJ and HMPPS work with stakeholders to address weaknesses in governance, data quality and system-wide inefficiencies to support a more reliable and responsive service.

Recommendations

a In the short-term, to manage rising demand, MoJ and HMPPS should, by September 2026:

set out a proposed system-wide approach to risk management, and share this with partners to support a coordinated response;

set out the key operational intelligence needed from partners, and make best use of available information to monitor emerging capacity, performance and public protection risks, recognising this will be incomplete; and

establish comprehensive escalation thresholds and contingency plans, setting out when and how senior leaders should intervene where system performance or capacity deteriorates.

By December 2026, they should also:

produce a clear plan to strengthen the evidence base on electronic monitoring (EM) effectiveness further, including how this evidence might inform priorities for EM if delivery capacity becomes constrained.

b Beyond this, to strengthen oversight of EM performance across the system, MoJ, the Home Office, the Judiciary, HMPPS and HM Courts and Tribunals Service (HMCTS) should ensure there is a senior cross-system forum with a clear mandate to oversee performance, risk and capacity. This could build on existing governance structures, provided these operate at a sufficiently senior level and with the necessary authority. This forum should:

agree ownership and accountability of system performance, roles and responsibilities, including escalation routes;

oversee a core set of system-wide performance and risk metrics;

oversee integrated capacity planning across suppliers, probation and police;

improve data-sharing and information flows to support decision-making and accountability; and

ensure stakeholders have a shared understanding of how the system is intended to operate by commissioning clear guidance and training.

c To improve system efficiency, HMPPS should work with others to:

estimate the costs of system inefficiencies and financial benefits of potential productivity improvements (for example, reducing manual re-keying of data) to inform where and how it could intervene;

put more ‘lead’ measures of process quality and control effectiveness in place to identify where and why problems happen, to identify and resolve issues;

ensure that all staff understand how to escalate problems and suggest improvements;

complete rollout of its new order system, to reduce inefficiencies caused by poor data and timing of orders;

consider taking a system-wide risk-based approach to handling alerts and breaches while maintaining public protection; and

assess the value of expanding pilots of fitting tags at source in courts.

d To improve the EM court bail process, MoJ and HMCTS should work with HMPPS and other stakeholders to understand, improve and then analyse data on court bail outcomes to understand police concerns around EM effectiveness for this group. They should then work with stakeholders to resolve any issues identified.

e To ensure its future procurement approach supports its plans to stabilise and transform EM, in the medium term, HMPPS should:

assess a range of options to inform its future procurement scope;

define clear, evidence-based outcomes and areas requiring clearer specification for the EM service and co-design solutions with stakeholders, using pilots where appropriate and learning from previous contracts;

if outsourcing, engage the market early to support effective competition and transitions; and

put robust assurance arrangements in place before service commencement.

Part One

Overview of electronic monitoring and its aims

1.1 This part of the report explains what the Ministry of Justice (MoJ) and HM Prison and Probation Service (HMPPS) intended the electronic monitoring (EM) system to achieve since 2021, and how it was intended to work.

What is EM and how does it work?

1.2 EM uses technology to remotely monitor a person’s location and compliance with community orders, court and immigration bail conditions and conditions post release from prison. Potential breaches (non-compliance with EM conditions) are reported to relevant agencies for response including the police, probation and Home Office. Individuals usually wear a tag around their ankle, although in immigration cases they may carry a non-fitted device. The system requires information flows between private suppliers and agencies in the criminal justice system. Figure 1 sets out how the EM system works and the various roles and responsibilities of the organisations involved.

1.3 The EM service refers to the supplier-delivered tagging and monitoring contracts. MoJ holds the contracts for the EM services in England and Wales, while HMPPS is responsible for overseeing delivery, which involves the tagging and monitoring of individuals and managing supplier performance.¹ In October 2023, MoJ awarded EM contracts to Allied Universal Electronic Monitoring (Allied) to supply the tags and monitoring system, and to Serco to fit and remove the tags, and to monitor compliance of those with tags. The new service went live in May 2024. Airbus currently provides the platform that enables mapping for acquisitive crimes (such as theft) although this contract expires in January 2027.2

Spending on EM

1.4 HMPPS estimates that it costs on average £4,900 per year to electronically monitor an individual, equating to an estimated annual direct cost of £133 million for 2025-26. These figures include costs incurred by probation, but exclude wider system costs, such as those incurred by the police and courts.

MoJ and HMPPS’s aims for EM from 2021

1.5 HMPPS launched its EM expansion programme (the programme) in January 2021, completed in June 2026. A key driver of the programme was the expiry of existing contracts with Capita and other suppliers in April 2024, requiring HMPPS to reprocure tagging and monitoring services. More widely, HMPPS aimed to support the government’s aims to maximise the use of EM, by expanding EM to new groups and promoting EM as an alternative to custody for some cases. It also recognised the need to better understand and improve the effectiveness of EM. In September 2021, the government committed to increasing the EM population from around 13,500 to 25,000 by 2025. HMPPS expected to achieve this largely through increases in GPS and alcohol monitoring tags for prison leavers.

1.6 HMPPS aimed to address previous contract weaknesses through the programme and the new contracts. These weaknesses had included HMPPS’s lack of access to supplier data, which had limited HMPPS’s ability to improve the service and constrained the effectiveness of EM as a tool for managing offenders in the community. The programme aimed to develop a flexible and scalable service, improve data and the evidence base for EM, integrate EM more closely with probation and ensure cost effectiveness (Figure 2). It intended to do so through contract and service design changes. For example, MoJ consolidated eight supplier contracts into two, introduced more flexible arrangements to allow for expansion and introduced a new case management system (ServiceNow). It also aimed for improved data governance and interfaces between EM and wider criminal justice systems to improve data quality and insights. HMPPS expected these changes to improve compliance and sentencer confidence and to deliver around £157 million in cost savings.

Defining what good looks like

1.7 In June 2022, MoJ set out its policy ambitions in its EM strategy, aligned to the programme’s aims. MoJ framed EM as a tool to support its broader priorities of reducing reoffending and protecting the public. The strategy envisaged a robust, innovative and data-driven system to provide officials, such as probation staff or the police, with accurate and timely information. This would enable officials to identify and respond quickly to breaches, supporting more responsive offender management. It intended these improvements to increase compliance, strengthen confidence in EM, and mitigate the risks of managing offenders in the community instead of custody.

1.8 Some stakeholders we spoke to did not understand how responsive MoJ intended the system to be, with some expecting immediate police or probation action following a breach. Contractual arrangements mean Serco has between 29 and 53 hours after a breach before it is required to provide breach details to officials, after an initial notification (Figure 3). In practice this can occur sooner or later (see paragraph 2.12 for recent timings). There is a very small number of ’specials’ cases where Serco is contracted to respond to breaches more quickly due to the high risk involved.³

1.9 The EM strategy aimed to provide a more responsive system. However, neither MoJ nor HMPPS has defined how quickly it intends partner agencies to react to breaches of EM conditions. Police forces and courts do not have service level agreements setting out expected response times and performance standards due to their operational independence. Police forces in England and Wales follow the Receive, Assess, Decide and Update (RADU)⁴ process, but there are no set targets for response times to breaches, nor an agreed approach to prioritising cases. Within probation, timeframes for responding to breaches are largely undefined, with some exceptions. For example, national guidance requires probation administration staff to prompt probation staff after five days, where an individual has breached their EM conditions, but no outcome has been recorded.

1 HMPPS is also responsible for the EM service in Northern Ireland and Scotland for immigration bail.

2 See Figure 12 for more information on the acquisitive crime mapping tool.

3 This includes individuals managed under multi-agency public protection arrangements, those granted bail by the Special Immigration Appeals Commission, and those made subject to Terrorism Prevention and Investigation Measures.

4 Under the RADU process, police receive information on a breach, assess the information, decide on the appropriate response, and update Serco with the decision. It is used to determine whether an EM breach warrants police investigation or action and prioritise accordingly.

Part Two

Electronic monitoring system performance

2.1 This part assesses the extent to which the Ministry of Justice (MoJ) and HM Prison and Probation Service (HMPPS) met their expansion goals for electronic monitoring (EM), and whether the system is operating in line with their expectations. It also sets out operational challenges affecting performance.

Expanding the use of EM

2.2 Through its expansion programme (see paragraph 1.5), HMPPS broadened the use of GPS and alcohol tags to new groups. This included:

introducing compulsory GPS tagging for people on probation convicted of acquisitive crimes, such as theft, first piloted in April 2021 and later expanded to 19 police force areas;

expanding alcohol monitoring through the national rollout of the Alcohol Abstinence Monitoring Requirement for some community sentences in March 2021, and rolling out alcohol monitoring for some prison leavers from November 2021 in Wales and June 2022 in England; and

the expansion of EM to adults released from prison on licence who are at risk of committing domestic abuse in some probation areas from August 2023.

HMPPS met its target of increasing the EM population in England and Wales from around 13,400 in January 2021 to 25,500 by June 2025, rising further to 28,700 by March 2026 (Figure 4).⁵ As at March 2026, individuals tagged after release from prison formed the largest share (37%), followed by those on court bail (34%).

Using data to understand system performance

2.3 Through the new contracts, MoJ and HMPPS sought to improve access to performance data from the main suppliers, Serco and Allied Universal Electronic Monitoring (Allied), and set contractual key performance indicators (KPIs) to monitor and manage performance. Serco’s KPIs cover fitting and removing tags, monitoring individuals and maintaining supporting systems. Allied’s KPIs focus on monitoring system performance and resolving technical incidents quickly. HMPPS has made improvements to data quality, including automated validation checks and an EM data store which, as of December 2025, receives live data from suppliers. This provides greater transparency compared with previous EM contracts.

2.4 Despite these improvements, poor data quality continues to limit HMPPS’s ability to understand and manage EM performance. We heard that data are often poor at source (for example, from courts), processes remain complex and manual data entry and workarounds introduce errors. Delays to the contract transition (see paragraph 2.6) also meant that dual systems were running until late 2025, complicating data reconciliations. HMPPS has therefore found it difficult to assure supplier performance. Serco has improved data quality during the current contract. However, in February 2026, HMPPS reported it was still uncertain whether data were being captured and processed correctly.

2.5 MoJ and HMPPS also lack a robust, data-led view of how the EM system performs overall (Figure 5). The expansion programme’s benefits framework captures some aspects of EM performance. However, it does not provide a complete picture of how the system operates overall, particularly on how often officials respond to breaches, or the number that result in enforcement action.

Supplier performance

2.6 Delays and delivery challenges during the transition to the new EM suppliers undermined early operational performance. MoJ awarded contracts to Serco (£330 million) and Allied (£175 million) between September and October 2023.6 Both contracts run until April 2030, with an option to extend by up to two years to April 2032. Serco took over the service from Capita in May 2024. However, ‘full operational status’, defined by the completion of migrating systems and devices from previous EM contracts, was not achieved until October 2025, 11 months later than planned. During this period, there were delays in fitting tags, and the backlog of tagging visits (for tag fitting, removal and maintenance) rose from 1,200 in May 2024 to 7,000 by October 2024 (Figure 6). These backlogs forced Serco to prioritise reducing the backlog over completing its transition to new systems, extending the time that both legacy and new systems operated in parallel. Allied met most of its original contractual requirements on time, including those required to meet the key transition timeline. However, challenges delivering additional technical requirements, not in the original contract, contributed to later delays. HMPPS also found that some early deliverables, such as Serco’s ServiceNow system and Allied’s new alcohol monitoring device, did not meet required standards and needed rework. Delays resulted in a £42 million overspend against the expansion programme’s baseline budget of £858 million. This was due to extending previous contracts and longer than planned cost-plus payments to Serco during its transition period to the new service, in line with its contract terms.⁷

2.7 Serco did not meet most of the targets that applied before ‘full operational status’ was reached. In the contract, MoJ and HMPPS set 14 contractual KPIs to measure Serco’s performance, spanning the range of the service. However, from August 2024, they formally assessed Serco against a reduced set of four KPIs, recognising the significant service changes required. The four KPIs covered a limited range of activities, such as equipment reinstallation and removal, but not key aspects of service delivery, such as attempts to fit tags on time. Against the KPIs that did apply, performance was often significantly below targets for all but one between August 2024 and July 2025 (Figure 7). While Serco was not contractually held to account against wider service measures, HMPPS still tracked performance against the full range of services that it intended to use in its KPIs later. This monitoring indicated significant weaknesses, including delays in breach notifications to officials and in visits to fit, remove or check tags. For example, in most months, Serco sent fewer than half of breach notifications within the contractual timescales that would apply under the full KPI regime.

2.8 Allied has only two KPIs for system performance and time taken to resolve technical incidents. It met both KPIs for just over half of the months between August 2024 and April 2026 (Figure 7).⁸ System availability worsened in late 2025, during the delayed transition period. This included a significant network-related outage in September, which disrupted tag installations and followed a higher-than-usual level of technical incidents. Performance has since improved in the most recent period to April 2026 (the latest period for which data are available).

Improving supplier performance

2.9 Our review found that delays in transitioning to new systems were driven by a combination of supplier performance issues, challenges in managing interdependencies between suppliers, and an underestimate of transition complexity by HMPPS. This underestimate included limited contingency planning and insufficient early assurance of system readiness and testing. The programme was highly interdependent, with completion of migration activities, system readiness and supplier integration closely linked. We heard differing views from suppliers on the extent to which delays were attributable to dependencies on other parties. HMPPS told us it felt the main reasons for delays in transitioning to new systems were Serco’s lack of preparedness and its underestimation of the complexity of the changeover. It also acknowledged weaknesses in its own approach, including unclear system requirements in some cases. Serco acknowledged that it underestimated system complexity and had rolled out a new IT system before fully understanding operational processes, which contributed to the increased backlog. It also cited inheriting an unexpected backlog of 1,200 visits, high rates of staff sickness, and delays from others. Allied told us that the decrease in system stability in late 2025, was partly due to delays in Serco’s transition plans, which required it to divert staff from business-as-usual activities. Under the programme’s delivery model, responsibility for managing these interdependencies sat primarily with Serco in its role as service integrator. However, MoJ and HMPPS retained overall accountability for ensuring these arrangements operated effectively.

2.10 HMPPS has used contractual levers and worked with suppliers to improve performance. Supplier contracts include a progressive set of penalties for under-performance, from financial penalties (for example, service credits for missed KPIs) to contract termination as a last resort. Contracts do not include positive incentives, such as financial rewards for meeting major milestones. For Serco, although the contract envisaged a move to the full set of 14 operational KPIs from November 2024, this transition did not take place until November 2025, after achieving full operational status in October 2025. At this time, MoJ and HMPPS agreed a period of gradual improvement against contractual KPI targets up to February 2026. Before this, HMPPS worked with Serco to implement a rectification plan to help stabilise backlogs. It also set a tolerance level of 400 outstanding visits over three days, which it used to monitor progress. The visits backlog was back below 400 by November 2024, although this is not a contractual target. Alongside this, Serco strengthened its performance management, with KPI data reviewed several times daily to prioritise staff time. HMPPS acknowledged that changes to Serco’s leadership team in October 2024 helped drive performance improvements. It explained that it had charged suppliers the maximum amounts permitted under the contracts for performance levels recorded from Serco for poor performance and transition delays, and from Allied for poor performance. Performance against targets improved over time, with Serco meeting all contractual KPI targets in March 2026 (Figure 7).

2.11 Serco’s KPIs do not show how well the system performs overall on issues, such as timely tag fitting. For example, Serco meets one of its KPIs if, for 95% of its cases, it makes two attempts to install a tag for an adult by midnight on the day after receiving an order. In February 2026, although Serco met its 95% timeliness target for tag-fitting visits, it was only successful in fitting a tag for 62% of the individuals it visited after those two attempts.

Wider system performance

2.12 Available evidence suggests that significant weaknesses in the system are undermining MoJ and HMPPS’s aims for EM. This is particularly noticeable for objectives to manage offenders safely in the community, respond swiftly to breaches, and protect the public.

HMPPS does not have an accurate understanding of the number of individuals who should be monitored but are not (‘unmonitored’), posing potential risks to public protection. As at March 2026, about 8,900 active EM cases – 24% of those required to be tagged – were under review to identify how many were unmonitored. HMPPS told us these cases under review include some cases which remained active by error. HMPPS has a new definition of ‘unmonitored’. This now includes active EM cases where an individual has not been tagged, and those whose device has been disconnected for 14 days or more, for example because they have not charged their tag. Individuals with disconnected devices are currently included within the tagged caseload and are not included within these 8,900 cases under review. HMPPS expects to publish statistics on the number of unmonitored individuals in late July 2026.

Limitations in breach information affect officials’ ability to respond. Police reported that early breach information they received previously lacked sufficient detail to allow them to re-arrest individuals, though this has now improved. Probation staff at an office we visited told us contracted times for breach notifications felt too long and breach packs (produced by Serco to notify officials of a breach) are often lengthy and difficult to interpret. As at February 2026, Serco was providing the packs within 20 hours on average across all cases after receiving a tag alert.

Both probation and police report a lack of capacity to respond promptly to breaches. They reported that limited capacity often prevents prompt responses to breaches, though no data are available on this.

Police raised concerns that breaches of court bail EM conditions result in limited consequences when cases return to court. They told us that courts frequently re-imposed the same conditions after a breach. We were unable to verify how often this happens as MoJ and HMCTS do not routinely analyse data on court outcomes in this way.

Understanding and managing the impact of the unmonitored population

2.13 The unmonitored population is HMPPS’s highest priority performance issue, but data limitations mentioned in paragraph 2.12 mean it lacks an accurate picture of which cases require action. HMPPS has set an indicative tolerable level for the proportion of unmonitored individuals to be 15% of all individuals with an active EM order, but acknowledges that current levels are likely above this. Poor quality data (see Figure 5) mean that HMPPS cannot reliably identify how many cases require action or how long individuals remain unmonitored for and whether they reoffend. By March 2026, HMPPS had begun cleansing its records. However, as at May 2026, significant uncertainty remained limiting HMPPS’s ability to effectively manage one of its most significant risks.

2.14 Data weaknesses (see paragraph 2.4) in the EM system also increase workload elsewhere. For example, some probation teams are spending significant time identifying and tracking unmonitored individuals. HMPPS told us it reviews Serious Further Offences (SFOs) for any links to EM failures and has not identified an increase linked to such failures. It expects its new data store, together with the EM Data Insights tool (see figure 12), to provide a better end-to-end view once these are fully implemented.

HMPPS’s approach to addressing inefficiencies to improve performance

2.15 HMPPS and its stakeholders have worked together to resolve issues and make improvements. For example, HMPPS is rolling out a new ordering system, called Create an EM Order (CEMO), to address data quality issues through increased automation. It is also running some pilot schemes to trial new processes, such as tagging offenders before they leave prison (see Figure 12). Additionally, Serco commissioned a review of the system in 2025 to identify system failure points.

2.16 However, our work and recent reviews found that significant inefficiencies persist across the system (Figure 8). Key issues include the following:

High error rates in EM orders delay tagging and waste resource. Serco receives around 1,300 tasks per day from agencies, some of which are incorrect or incomplete.⁹ Court staff told us errors are common because orders are manually typed and often entered during live hearings, where staff work under time pressure. HMPPS intended CEMO to address these issues; however, it still had error rates of around 21% as at May 2026. HMPPS told us CEMO is not due to be fully rolled out until December 2026.

Low tagging success rates create cost and inefficiency. Only 45% of adults were successfully tagged within the standard number of attempts in 2025.10 Between January and April 2026, the proportion was 62%.¹¹ Low tagging success rates are driven by factors both within and outside of the supplier’s control. These include individuals not being at the address at the time of the visit, refusal to be tagged, and late receipt of EM orders from government agencies.

High volumes of alerts and breach notifications, combined with a lack of risk-based prioritisation, absorb significant resource but generate limited value. An MoJ-commissioned review found there are between 530,000 and 3 million alerts a year, including 3% to 10% caused by software errors. Staff must review all alerts but only 10% to 50% progress to a breach pack (where details of a breach are sent to officials). Of the 20% to 27% of those that have an outcome recorded, nearly half of those outcomes result in ‘no further action’. These data suggest a high level of unnecessary noise and workload. On our visit to a police force, we observed different types of breaches, including significant unmonitored time periods of high-risk offenders and shorter unmonitored periods or breaches due to technical issues. However, all alerts and breaches often appear to be treated similarly, irrespective of duration or technical cause, although we recognise the police have discretion to pursue alternative outcomes.

Low device collection rates reduce available stock. Only around 60% of devices are collected successfully after an order ends, as of May 2026.

Causes of inefficiencies

Impact of contract transition issues

2.17 Issues with the transition to the new contracts (see paragraph 2.6) affected system efficiency. For example:

over optimistic timescales and work required to resolve transition issues and backlogs delayed planned productivity improvements, including Serco’s planned automated scheduling for field visits;

HMPPS told us that early uncertainty over responsibility for developing CEMO delayed its rollout; and

Stakeholders, such as probation staff, were not sufficiently involved in system and process design, resulting in some examples of solutions that did not meet their needs. For example, we heard that Serco’s new case management system, ServiceNow, was more complex than expected and did not meet operational needs.

Lack of a whole-system approach

2.18 Our work shows that effective whole-system working requires clear end-to-end accountability, shared problem-solving, a single process owner and effective data-sharing.¹² The EM system involves several organisations outside of MoJ and HMPPS’s control. There is currently no overall process owner, making it difficult to resolve issues across organisational boundaries. For example, an MoJ-commissioned review found that Serco often has to correct errors from HMPPS and HMCTS due to weak accountability for order creation. Many front-line staff we spoke to were unclear how to raise cross-system issues or suggest improvements. HMPPS has established cross-organisational groups and meetings, but progress often depends on goodwill.

2.19 HMPPS also lacks timely indicators of process quality to identify where problems occur and why. Management information focuses mainly on Serco and Allied’s KPI performance, with limited insight on the quality of process hand-offs between organisations. This means that HMPPS has relied on one-off “deep dive” reviews to understand the scale and causes of problems.

Effectiveness of EM

2.20 Paragraph 1.7 sets out MoJ and HMPPS’s intentions that EM helps reduce reoffending and protects the public. Since our last report in 2022, MoJ and HMPPS have improved the evidence base for EM effectiveness, publishing three impact evaluations in 2025.13 These show promising signs for the use of EM while individuals are tagged. For example:

the use of radio frequency tags was associated with lower reoffending for suspended sentence orders and community orders, with reductions of around eight and 11 percentage points respectively;¹⁴

the use of GPS tags was associated with lower reoffending of around seven percentage points for some crimes, such as theft and robbery; and

the acquisitive crime project freed up police time and reduced unnecessary arrests (an estimated 16,000 fewer arrests), by enabling police to rule out suspects.¹⁵

2.21 However, gaps in the evidence base remain. The evaluations do not yet allow MoJ to draw firm conclusions that EM reduces reoffending beyond specific groups or in the long-term. While a further impact evaluation of the ‘domestic abuse perpetrators on licence’ pilot is underway, current evidence is still insufficient to identify which groups benefit most or how effectiveness varies. Without this understanding, MoJ lacks a robust basis for prioritising or targeting EM if capacity becomes constrained as demand increases.

5 Changes to HMPPS definitions mean that the number of people tagged in 2021 is not directly comparable with the number tagged after June 2025.

6 Contract values are inclusive of extension costs.

7 A ‘cost-plus payment’ is a payment mechanism where the supplier is reimbursed for actual costs, plus an additional fee or margin to cover profit.

8 First month of available Allied KPI data.

9 Serco receives around 1,300 tasks per day from government agencies, which include 220 new EM orders on average.

10 For adults, Serco is required to make a second attempt to fit a tag if the first attempt is not successful.

11 These two sets of data are not directly comparable as the time periods they cover are different.

12 National Audit Office, Improving operational delivery in government: A good practice guide for senior leaders, March 2021.

13 MoJ also published an interim impact evaluation of the ‘alcohol monitoring on licence’ scheme in 2025, which found that alcohol monitoring did not have a statistically significant effect on recall to prison.

14 The estimated reductions of eight and 11 percentage points are based on 12-month proven reoffending, using Police National Computer data. A separate MoJ evaluation using court reconviction data reported smaller differences between the treatment group (those with radio frequency tags) and the comparison group. The two measures are not directly comparable because proven reoffending and court reconvictions are defined and measured differently.

15 The acquisitive crime project is a scheme to tag those convicted of specific acquisitive crimes, such as theft.

Part Three

HM Prison and Probation Service’s plan to ‘stabilise, scale and transform electronic monitoring’

3.1 This part of the report sets out HM Prison and Probation Service’s (HMPPS’s) plans to ‘Stabilise, Scale and Transform Electronic Monitoring’ (STEM). It assesses whether the system is resilient to rising demand following the Sentencing Act 2026 (the Act), and the risks HMPPS must manage.

The Sentencing Act 2026

3.2 In September 2025, the government announced its Sentencing Bill to address the prison capacity crisis by managing more offenders in the community. Electronic monitoring (EM) is key to the government’s response. The Act was passed in January 2026, with some measures taking effect from March 2026. The government has allocated up to £175 million to fund the EM expansion over the 2026–2029 spending review period. This includes up to:

£105 million to support the increasing use of EM resulting from the Act, including £21 million for tag purchases;

£25 million for digital investment to support EM;

£23 million for further growth in the number of people on EM, unrelated to the Act; and

£22 million for enhanced probation supervision of the highest-risk individuals.

3.3 Figure 9 outlines how the Act and associated changes will affect the number of people tagged. In September 2025, before implementation decisions were finalised, the Ministry of Justice (MoJ) estimated that these changes could require up to 22,000 more individuals to be tagged each year from 2027.16 England and Wales collectively are among the countries with the highest number of people tagged relative to country population size.¹⁷ The projected net increase included around:

8,000 more court bail cases, reflecting expanded powers to impose EM and an increasing court backlog;

1,000 more community orders that include EM – the Act was expected to divert more offenders from custody into community orders; and

13,000 more people tagged after leaving prison – driven by government’s new presumption of tagging prison leavers who will be released earlier under the Act’s earned progression model.

The September 2025 estimate was produced before details of the scheme had been finalised. Since then, MoJ has decided that many offenders will be released after serving a third of their sentence and will be tagged until the 40% point of their sentence. Offenders serving sentences for more serious sexual or violent offences will be tagged on release after serving half of their sentence until the 67% point of their sentence. MoJ has also decided to exclude from its tagging presumption individuals who would spend fewer than 30 days on a tag and those for whom tagging is not suitable, for example due to homelessness. Its decision to further rollout domestic abuse perpetrator on licence (DAPOL) and acquisitive crime (AC) schemes will also increase EM use.

3.4 As at June 2026, MoJ had not completed updates to these projections, but early estimates indicate that expected increases remain broadly consistent with the September 2025 projections. However, these projections have a high level of uncertainty. This is due to potential further policy changes, including outstanding Sentencing Act policy decisions and the impact of Leveson’s Review of Criminal Courts.¹⁸ There is also significant uncertainty surrounding how policy decisions will be implemented in practice. Projections for how many people it expects to be tagged at any given point in time will be lower than projections of the number of individuals tagged over a year due to churn. For example, although more people are expected to be tagged following release from prison, many are expected to spend short periods of time on a tag.

The STEM plan

3.5 In response to rising demand and reform pressures, HMPPS agreed its ‘Stabilise, Scale and Transform Electronic Monitoring’ (STEM) plan in October 2025 to strengthen EM resilience. The plan aims to stabilise the EM service; build the foundations needed to scale up activity; and transform service delivery through new technology and data across 12 workstreams (Figure 10). HMPPS’s plans incorporate some planned improvements that were not completed within its 2021–2026 EM expansion programme and some lessons from external reviews. HMPPS aims to deliver key activities from the first 10 workstreams over spring and summer 2026, before the earned progression arrangements start in prisons from September (Figure 11).

3.6 HMPPS is developing innovations and pilots to support its plans (Figure 12). It has assessed market options and international EM programmes to inform its future approach. For example, it plans to pilot improved management of domestic abuse offenders through tags that can monitor their proximity to their victim – a technology used in countries including Spain, Italy and Australia. It also plans to strengthen offender management by providing probation officers with quick access to EM data through its EM Data Insights tool. Innovations are supported by HMPPS’s ongoing digital and data systems improvements, complementing supplier systems. Some of these innovations were originally part of the EM expansion programme, but delays and issues with data quality mean HMPPS transferred some aspects to the STEM plan (Figure 10 and Figure 13).

3.7 HMPPS is also introducing a new single service ownership (SSO) model to streamline EM governance and provide clearer oversight of its STEM plan. EM operates across different parts of the criminal justice system, but governance, risk ownership and accountability is fragmented. The SSO is intended to resolve cross-workstream dependencies and delivery risks. However, key stakeholders, such as the police, HMCTS and the judiciary, remain outside HMPPS’s leadership. This limits access to data and means that no single organisation is accountable for overall performance. As a result, the SSO relies on collaboration to address cross-system issues.

Understanding and managing demand and capacity

3.8 MoJ’s demand projections have been fairly accurate to date. MoJ’s estimates are based on historical data, policy impact assessments and inputs from external stakeholders across the EM system. MoJ was required to update its projections every quarter and HMPPS to provide these to suppliers and partners for their planning. However, projections were updated in March 2026, 16 months after the previous projections in November 2024. This delay resulted from significant data quality issues and was compounded by uncertainty about the scope and timing of the Act. Stakeholders only received updated forecasts on 31 March 2026, although HMPPS expected its Fixed Term Recall scheme to create a short-term spike in EM demand from late March 2026.19 This timing limited suppliers’ and their partners’ ability to plan ahead, although available data for April and May 2026 do not show significant increases in outstanding visits, and supplier performance remained stable. Subsequent updates have incorporated emerging policy decisions and HMPPS plans to share updated projections with suppliers in late July.

3.9 HMPPS lacks a system-wide view of capacity constraints and relies heavily on provider intelligence. Suppliers, police and probation analyse their own resource and capacity. However, the absence of a joined-up approach to modelling resource and capacity makes it difficult to judge whether the system can absorb the expected increases in demand or assess its risk exposure.

3.10 HMPPS predicts that shortfalls in probation staffing will persist amidst increasing demand for EM, despite its central role in managing tagged individuals. Our 2025 report on the Probation Service set out the huge challenge HMPPS faced in closing a significant gap between actual and required probation capacity to address poor performance and high workloads.²⁰ Between 2023 and 2025, 31% of target probation appointments with offenders did not take place due to unmanageable workloads. Probation told us that staff responses to EM breaches were often delayed or missed. Since our report, HMPPS has reduced the scale of the staffing gap, but in March 2026, an estimated shortfall of 2,200 full time equivalent (FTE) probation staff remained. MoJ announced further probation reforms in March 2026 to help manage capacity pressures. The government has allocated £22 million to probation from the £175 million EM expansion fund for this. Since 2023, HMPPS has also invested up to £8 million annually to March 2028 to fund 183 specialist EM probation roles to support practice and performance. In the 2025 Spending Review, the government also committed to increase probation funding by up to £700 million (45% increase on 2025-2026) by 2028-29. HMPPS expects to have made further progress in closing the staffing gap by September 2026. However, it estimates that a shortfall of 1,500 FTE staff will remain at this point, reducing to around 600 FTE staff by January 2027. It is developing an implementation plan to manage additional pressures, including sequencing digital innovations, but it remains unclear whether this will be sufficient to meet increased demand.

3.11 The police are also uncertain how they will manage the increased EM population alongside existing pressures. MoJ has estimated that the police will need to respond to about 4,200 additional bail breaches each year that result in custody following implementation of the Act. Expected increases relate to both the expansion of court bail and increased use of EM. However, the police have not received additional funding for this. The National Police Chiefs’ Council estimated in September 2025 that changes to EM would cost the police around £20 million more per year. The police told us that, given resourcing pressures, they would need to balance responding to EM breaches with their other priorities.

Risk and resilience

3.12 Robust and effective risk management is critical to achieving the government’s objectives for EM and securing long-term value for money. Since we last reported in 2022, HMPPS has strengthened its risk management processes for parts of the EM system within its control, including its expansion programme and supplier performance. It has improved governance by establishing EM risk forums and appointing clear risk owners. It has also defined its risk appetite across 13 categories aligned to The Orange Book, including an operational risk appetite of ‘cautious’.²¹ HMPPS uses this infrastructure to inform decision-making and respond to risks. For example, it introduced additional assurance to improve monitoring and responding to changes in supplier performance. It has also increased focus on identifying weaknesses through cross-workstream reviews and risk planning tools, such as regular contingency reviews.

3.13 However, HMPPS is continuing to scale the service while key elements are not yet working effectively, leading the service to operate beyond its stated risk appetite and tolerance levels. Independent reviews identified significant issues in tagging orders and breach processes (see paragraph 2.16) and warned against further expansion until these were operating effectively. HMPPS aims to address these issues through the ‘stabilise’ and ‘scale’ workstreams of its STEM plan. However, it will not have completed all the actions in the ‘stabilise’ workstream before demand increases (Figure 11). In April 2026, it also identified a significant risk that EM processes and training may not be ready in time to support the implementation of the earned progression model and associated changes in September 2026. Delays in confirming key EM requirements and design decisions for the progression model (confirmed in March and May 2026, respectively), mean digital tools and operational processes may not be operational by September. As of May 2026, MoJ and HMPPS had made key design decisions, and HMPPS had implemented a range of actions that it considers have reduced the risk. The service has been operating outside its stated risk appetite and tolerance levels in several areas and is likely to continue to do so. This increases the risk of poor performance and threats to public protection escalating as demand grows.

3.14 The lack of overall system ownership means that there is no whole-system approach to risk management, limiting the government’s ability to manage and prioritise risk collectively. This increases the likelihood of uncoordinated or reactive responses to rising demand, which could delay partners in identifying operational or public protection risks. MoJ, HMPPS and partners have undertaken some recent cross-system work to identify and manage risks. But there is no overarching framework that sets out how increasing demand will be monitored and managed across the system. In particular, there is a lack of:

key performance data such as breach response times to detect emerging risks in good time.

clear early-warning thresholds and escalation routes if risks increase.

3.15 There are current and future risks to resilience of the EM delivery model:

From the outset, Serco planned to achieve efficiencies to reduce its operational service costs, including by increasing the proportion of single-officer visits, almost halving its field workforce. However, delays to service migration, some of which were outside of Serco’s control, have prevented Serco from implementing these efficiencies as planned. Serco also told us that implementation of the Act has delayed planned efficiencies, including dynamic scheduling postponed from March to July 2026.22 As at May 2026, Serco planned to make workforce reductions before September 2026. This creates a trade-off. While reducing workforce capacity ahead of increases in demand could increase the risk of backlogs, retaining additional capacity to manage these risks creates financial pressures for Serco. As at June 2026, MoJ had agreed up to £48 million of additional payments to Serco over the contract life.²³ This includes up to £6 million to retain staff to help manage spikes in demand as the Act is implemented. These payments provide Serco time to implement planned cost reductions, in recognition that some programme delays were outside its control. The payments also fund some activities not covered by the contract, such as additional costs of workarounds due to delays in rolling out the new order system, Create an EM Order (CEMO). As at March 2026, £10 million had been paid to Serco.

Data gaps limit understanding of value-for-money risks, particularly for court bail cases. For example, as set out in paragraph 2.12, police told us that responding to court bail breaches is resource-intensive but often results in no action. The Act increases the risk that court bail inefficiencies will be amplified as demand grows. HMPPS lacks sufficiently granular data to understand the scale, causes and impact of this activity, limiting its ability to redesign processes or target interventions effectively.

The current supplier contracts will expire in 2030. HMPPS therefore needs to make early strategic decisions on future delivery models to secure a resilient and efficient future service. Through its STEM plans, HMPPS aims to develop a future operating model to inform the next phase of delivery, including considering reprocurement. It has begun initial stakeholder engagement on this. However, there is a risk that the need to address increasing pressures may divert focus from ongoing planning.

3.16 The EM system is operating in a highly volatile, rapidly changing environment. Poor performance, data gaps and fragmented governance constrain HMPPS’s ability to maintain critical EM functions and adapt to rising demand. Indicators of weak resilience include a potentially significant number of unmonitored individuals, instability in order and breach management processes, and weak visibility of breach responses and outcomes. Together, these weaknesses increase the risk that EM is scaled up without a clear understanding of system-wide risks and capacity constraints. This increases the likelihood of system disruption as demand rises.

16 To reflect the range of uncertainties in HMPPS’s estimate, we have rounded the figures provided to us to the nearest thousand.

17 This statement is based on a high-level international comparison using a small sample of selected countries (see methods, covered in the Appendix).

18 Sir Brian Leveson, Independent Review of the Criminal Courts: Part 1, July 2025; Sir Brian Leveson Independent eview of the Criminal Courts: Part 2, February 2026; accessed 15 June 2026.

19 A Fixed-Term Recall is a mandatory return to prison for low-risk individuals who breach licence conditions, with automatic release after a set period. It applies to those on standard determinate sentences of less than four years. The Act introduced a new 56-day Fixed-Term Recall for most offenders, replacing the previous 14-day and 28-day Fixed-Term recalls and standard recalls. On implementation, many individuals on standard recall who had already served 56 days were released through six tranches between March and May 2026. HMPPS planned to release around 2,300 individuals as at April 2026.

20 Comptroller and Auditor General, Building an effective and resilient Probation Service, Session 2024–2026, HC 1354, National Audit Office, October 2025.

21 Government Finance Function and HM Treasury, The Orange Book: Management of Risk – Principles and Concepts, updated June 2026; accessed 15 June 2026.

22 Dynamic scheduling is a system, that optimises field officer routes, scheduling and equipment, and sends appointment reminders to improve productivity and installation success.

23 Additional payments include potential contract extension costs.

Appendix One

Our audit approach

Our scope

1 We reached our independent conclusions on whether HM Prison and Probation Service (HMPPS) can deliver electronic monitoring (EM) efficiently and effectively, and whether EM is capable of taking on the strategic role envisaged for it in the criminal justice system in future, by analysing evidence collected between December 2025 and June 2026.

2 We formed our conclusions after considering three audit questions:

Have the Ministry of Justice (MoJ) and HMPPS set out clear aims for the new service, how it should work and how it will measure success? (Part One).

Has HMPPS understood and responded to factors influencing poor early operational performance in EM and their impacts? (Part Two).

Do MoJ and HMPPS have plans to ensure EM is resilient and capable of meeting expected increases in demand? (Part Three).

3 We focused on electronic monitoring in the adult criminal justice system and therefore did not assess the tagging process for immigration cases or young offender cases in depth. While we examined what lessons HMPPS has learned from the previous EM service we did not assess HMPPS’s procurement process for the new EM contracts awarded to Serco and Allied Universal Electronic Monitoring (Allied). Similarly, while we assessed how the delivery of HMPPS’s 2021 electronic monitoring expansion programme has contributed to the performance of the system, we did not seek to evaluate delivery of the programme in full.

Our evidence base

Interviews

4 We interviewed officials from HMPPS, MoJ and other stakeholders in-person and remotely, using topic guides we developed from our audit questions. The purpose of the interviews was to develop an understanding of each stakeholder’s perspective of the current state and future potential of EM. The interviews also helped us test and triangulate evidence obtained from document review, data analysis and site visits. In total we conducted 33 interviews covering topics including:

the tagging process;

the performance of the EM service;

third-party contractual arrangements and supplier performance;

the potential impact of the Sentencing Act 2026 on the EM service; and

how HMPPS has adapted its work programmes and objectives to monitor performance in preparation for service expansion.

5 In addition to officials from MoJ, and from HMPPS as the executive agency responsible for prisons and probation services (including oversight of electronic monitoring), we interviewed staff from the following organisations:

Nottinghamshire Police: Responsible for policing in the Nottinghamshire area, including the use of EM data to support enforcement and public protection.

Metropolitan Police: Responsible for policing in the Metropolitan Police district, including engagement with EM for monitoring and investigative purposes.

HMPPS (HMP Sudbury): Responsible for housing individuals in custody and participating in the delivery of a pilot to tag offenders at the point of release rather than at home.

HM Courts and Tribunals Service (HMCTS): Responsible for the administration of courts and tribunals in England and Wales.

Serco Group plc (Serco): A private supplier contracted to deliver electronic monitoring services.

Allied Universal Electronic Monitoring Ltd (Allied): A private supplier contracted to deliver electronic monitoring services.

Focus groups

6 We conducted focus groups with two Crown Court judges and two Magistrates judges. The purpose of the focus groups was to understand judiciary views of EM processes, opportunities and challenges, and confidence in the service for offender management.

Document review

7 We reviewed more than 800 publicly and non-publicly available documents from HMPPS, the Ministry of Justice (MoJ) and third-party stakeholders. This helped us manage the scope of the audit, deepen our understanding of electronic monitoring, inform discussions with stakeholders, and triangulate findings from other evidence sources. The documents reviewed included, but were not limited to:

HMPPS board minutes, risk registers and business cases, to assess governance and risk management arrangements;

operational and process documentation, to understand the service and how data flow through the system;

supplier contracts, to understand contractual requirements, key performance indicators (KPIs) and financial incentives;

supplier performance and contract management information, to assess how HMPPS monitors performance against contractual requirements;

internal audit reports and programme gateway reviews, to understand assurance findings and required improvements;

external reviews of the service, to identify previous findings and actions taken to improve performance;

ministerial submissions on electronic monitoring performance, to understand what issues are escalated and the decisions taken by ministers;

HMPPS electronic monitoring strategy and programme documentation, to assess how HMPPS is implementing its approach to the service;

demand and capacity analysis, to assess how prepared HMPPS is to respond to changes in demand; and

service level agreements, court and police documentation, and related correspondence, to understand coordination between delivery partners.

Quantitative analysis

8 We analysed HMPPS’s internal data and official government statistics on the number of people monitored over time; supplier and service performance metrics over time; and caseload model projections. We did not review the accuracy of these data. We highlight within the report where quality issues impacted our analysis.

Review of MoJ’s EM impact evaluations

9 We summarised findings from three impact evaluations published by MoJ in 2025. Two of these evaluations measure the impact of radio frequency (RF) tags on reoffending for the same EM groups but use different data sources and methodologies. The authors highlight a few important limitations in their reports. In particular, the statistics in the RF evaluations are classified as experimental and are therefore subject to a greater degree of uncertainty than official statistics.

10 In addition, the evaluations could not fully isolate the effect of RF tagging from other components of the sentence (such as curfew requirements) and results may be affected by unobserved differences between the monitored and comparison groups.

Site visits

11 We visited some key stakeholders operating within the EM service.

HMPPS, Wirral Probation Centre, Birkenhead, Liverpool on 19 January 2026.

Serco, Dornoch House, Birchwood, Warrington 21 to 22 January 2026.

Metropolitan Police, Sidcup Police Station, Station Road, Sidcup on 28 January 2026.

12 During these visits, we had walkthroughs of system processes and interviewed a range of staff, including front-line operational teams, contract management teams and Serco representatives.

13 The purpose of the visits was to strengthen our understanding of how the EM service’s processes operate in practice, how they have been reformed, and the key opportunities and challenges facing the service in practice. We also used our observations to triangulate evidence from other sources relating to our study questions.

Use of specialist expertise

14 We made use of specialist expertise within the National Audit Office to inform our findings and support our audit conclusions. For example, to assess HMPPS’s capability in operations management, we drew on experts from our People and Operations Management Hub who accompanied us on selected site visits and interviews and provided challenge on our findings. We also liaised with our Financial and Risk Management Hub to inform our assessment of HMPPS’s approach to risk management, and with our Commercial Hub to inform our assessment of HMPPS’s EM commercial contracts and contract management.

International comparison

15 We conducted a high-level comparison of EM services for a sample of countries to provide contextual insight into how EM is designed and delivered outside England and Wales. The case studies were chosen to reflect a range of scales of EM use, caseload and delivery models. The comparison was illustrative rather than exhaustive. Our sample included the following countries:

Australia.

Germany.

Ireland.

Scotland.

South Korea.

Spain.

United States of America.

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DP Ref: 017011-001