Official Statistics

Technical note

Published 16 October 2025

Applies to England and Wales

1. Introduction

The Electronic Monitoring Statistics publication covers the use and delivery of electronic monitoring in England and Wales, using four types of devices: curfew monitoring devices (also known as radio frequency or RF devices), location monitoring devices (also known as global positioning system or GPS devices), alcohol monitoring (AM) devices, and non-fitted devices (NFDs). A small number of individuals in the immigration cohort living in Scotland and Northern Ireland are also monitored.

2. Overview of Electronic Monitoring Statistics

Background

Electronic monitoring supports probation services, prisons, courts, the police, the Home Office, and the wider justice system in England and Wales. It is a way of remotely monitoring and recording information on an individual’s whereabouts or alcohol consumption, using an electronic device that is typically fitted to an individual’s ankle. Electronic monitoring may be used:

• as a condition of court bail;

• as a requirement of a court sentence, primarily community orders and suspended sentence orders;

• for Home Detention Curfew;

• as a licence condition following release from custody;

• as a condition of immigration bail, managed by the Home Office; or

• to intensively monitor a small number of individuals, including: some of the highest-risk offenders managed under Multi-Agency Public Protection Arrangements (MAPPA); those granted bail by the Special Immigration Appeals Commission (SIAC); and those made subject to Terrorism Prevention and Investigation Measures (TPIMs).

Electronic monitoring was first introduced in 1999 to monitor compliance with curfews using curfew (RF) devices. These continue to be used where curfew is the only requirement. The service was expanded from November 2018 to introduce satellite enabled location monitoring devices. These devices use GPS technology which can record an individual’s movements 24 hours a day. Roll out was fully completed in March 2021 with the provision of location monitoring for under 18s.

GPS devices provide additional functionality, allowing the monitoring of:

• compliance with exclusion zones;

• attendance at a required activity or appointment;

• an offender’s whereabouts, known as trail monitoring.

• multiple conditions or requirements if necessary, such as a combination of exclusion zones, curfew, monitored attendance and trail monitoring.

Since 2021 HMPPS has expanded the use of GPS devices for the following offender cohorts:

• Acquisitive crime: From April 2021 trail monitoring has been used as a mandatory licence condition for eligible adult offenders convicted of an acquisitive crime as their principal offence and who have received a custodial sentence of 12 months or more and been released on licence. In late October 2022 this was expanded to those who had received a custodial sentence of 90 days or more. This is currently being piloted by 19 police forces.

• Several small pilots for specific offender cohorts, such as Licence Variation, GPS Youth Referral Order with Intensive Supervision and Surveillance (YRO ISS), and Domestic Abuse Perpetrators on Licence.

• Immigration expansion: The Immigration Act 2016 introduced a duty on the Home Office Secretary of State to impose an electronic monitoring condition on Foreign National Offenders (FNOs) and other non-UK citizens subject to deportation proceedings. Following this, in August 2021, HMPPS began using GPS monitoring for those individuals who had been released from prisons or Immigration Detention under ‘Immigration Bail’ on behalf of the Home Office. This was extended to Scotland from 31 August 2022 and Northern Ireland in December 2022. The Home Office ran a pilot from June 2022 to December 2023 to impose an electronic monitoring condition of immigration bail to non-FNO asylum claimants who arrive in the UK via unnecessary and dangerous routes.

Electronic monitoring using a non-fitted device was introduced in November 2022 for the immigration cohort. These devices utilise periodic biometric verification as an alternative to using fitted GPS devices. Those with a non-fitted device have been included within the GPS cohort for the purposes of this analysis.

Alcohol monitoring was introduced to courts in Wales in October 2020 and expanded to courts in England on 31 March 2021 to support the new community sentencing option, the Alcohol Abstinence and Monitoring Requirement (AAMR). An AAMR may only be used when sentencing for alcohol-related criminal behaviour and it imposes a total ban on drinking alcohol for up to 120 days. Compliance with the ban is monitored electronically using an alcohol monitoring device which continuously monitors for the consumption of alcohol via an offenders’ sweat.

An AAMR order may be imposed by the court as part of a community order or suspended sentence order where:

• the offence, or associated offence, for which the requirement is being imposed, is alcohol-related;

• the individual is not alcohol dependent or has an Alcohol Treatment Requirement (ATR) recommended or in place; and

• the individual is an adult (18 years or over).

For offenders being released from custody whose offending and risk is alcohol related, an Alcohol Monitoring on Licence (AML) additional licence condition was introduced in Wales in November 2021 and rolled out in England in June 2022. There are two licence conditions available for AML:

• requires total abstinence from alcohol, or

• requires the offender to comply with requirements specified by their Probation Practitioner to address their alcohol needs, which will include restricting alcohol use.

Data sources and methodology

The data in this release are compiled from Electronic Monitoring Services (EMS) contractor data and Alcohol Monitoring Services (AMS) contractor data, which in turn is derived from their case management systems.

New contracts to deliver the Electronic Monitoring service were awarded in October 2023, with Serco taking over the delivery of the service from Capita in May 2024. Details of the contracts can be found here. To ensure the publication series continued to meet high standards of accuracy and quality, official statistics were temporarily paused to allow us to revise processes for the production of statistics suitable for the new data source and to ensure good quality data underpinned the statistics.

Data included in this release are derived from both the previous provider (Capita) and the new provider (Serco).

The caseload statistics for curfew monitoring (RF), location monitoring (GPS) and alcohol monitoring presented in this release are not directly comparable to those published previously due to changes in the definition and methodology used to classify individuals as “tagged”. As a result caseload statistics are provided from June 2025 onwards.

Previous definition: An individual was considered tagged if they had any equipment assigned to at least one of their orders.

New definition: An individual is now considered tagged if all of the following conditions are met:

• Equipment is assigned to at least one of the orders, through a successful visit;

• The minimum required components for device monitoring have been input so that at least one monitoring requirement is fully met. Monitoring requirements are created to enable the monitoring of 7 possible enforceable conditions.

• There has been at least one confirmed successful installation of the device.

The statistics may differ from other statistics on electronic monitoring requirements due to the use of different data sources (such as those presented within the Offender Management Statistics Quarterly publications which are based on data held by the Probation Service).

An individual may be subject to multiple RF and GPS orders at the same time. In this instance the cohort under which an individual is counted is determined according to the following:

• if one GPS order (other than GPS bail), select this;

• if multiple GPS orders (other than GPS bail), select the order with the longest duration;

• if multiple non-GPS orders, select the order with the longest duration;

• if multiple GPS bail orders, select the order with the longest duration.

  New order notifications This is a count of all new order notifications, regardless of whether a device is fitted or whether an individual is already covered by another order.

  Completed order notifications This is a count of all completed orders, regardless of whether a device was fitted or whether an individual is still covered by another order.

Alcohol monitoring:

Migration of alcohol monitoring orders from Capita to Serco began at the end of July 2025. As with curfew (RF) and location (GPS) monitoring, the definition and methodology for reporting alcohol monitoring caseload statistics have been updated to align with the revised definition used across all electronic monitoring caseloads (as mentioned earlier). The number of new and completed alcohol monitoring orders is not impacted by the change of definition or considerable data quality challenges.

As with other device types, an individual can have multiple alcohol monitoring orders at the same time. In this instance the individual will be counted once, under the order type with the longest duration.

Dual-tagged: Some individuals are subject to both alcohol monitoring and electronic monitoring (RF or GPS). To avoid double counting in the overall summary statistics they are counted once in the order: AM order type, NFD order type, GPS order type (other than GPS bail) with the longest duration.

Prior to migration the number of duals were estimated by linking those that had a dual tag indicator on AMS with the EMS reference (where populated), or the name and date of birth, to EMS. Where this join produced a match, and both the EMS and AMS record was a) live at that date, and b) had a device fitted, the individual was considered as being dual-tagged. Dual-tagged individuals are now identified using a dedicated data field within the case management system.

Data limitations

Caseload details are received from the contractors at a regular frequency throughout the year. We conduct a range of quality assurance checks on these to identify any errors or inconsistencies in the data.

Prior to June 2025, it is not possible to reliably count unique individuals using the two systems, due to a high-level inconsistency between the two operating systems and data quality concerns. Some individuals appear in both systems, and some only in one, and there is no common unique identifier for individuals between the two systems. This is further hindered by missing or inconsistent person identifiable data to enable suitable identification.

These data quality issues have affected the caseload statistics, new orders and completed orders for curfew monitoring (RF) and location monitoring (GPS) prior to June 2025. We will consider whether anything can be done in the future to estimate this missing data.

For individuals with alcohol monitoring devices, the caseload period begins from the migration of alcohol monitoring data in July 2025. As with curfew (RF) and location (GPS) monitoring, the definition and methodology for reporting alcohol monitoring caseload statistics have been updated to align with the revised definition used across all electronic monitoring caseloads (as mentioned earlier). The number of new and completed alcohol monitoring orders is not impacted by the change of definition or considerable data quality challenges.

As the service continues to transition between systems, data has been compiled from multiple sources, where data are of high quality. We have actively identified and removed duplicate records by matching between the two systems, and we are confident such records account for less than 5% of the caseload and will continue to review data for subsequent publications.

There are a number of individuals who, according to the case management systems, are covered by a live order but do not have a device fitted. This could be for several reasons, such as the device not yet having been fitted. However, it can also arise from communication issues, such as the correct authority having not been informed when an individual has been recalled to prison. Furthermore, there are gaps in the evidence base that the administrative system cannot fill. Work is ongoing to address some of these limitations, including:

• continued development of the EM Data Dictionary, ensuring we capture the data we need and that terms are universally understood.
• exploiting technology to increase data sharing and provide one version of the truth.

Symbols and conventions

The following symbols have been used throughout this publication.

Symbol	Description
0	nil
-	not available
..	suppressed (see confidentiality section)

3. Notes

Confidentiality

This statement sets out the arrangements in place for protecting persons’ confidential data when statistics are published or otherwise released into the public domain. The Code of Practice for Statistics states that:

“Organisations should look after people’s information securely and manage data in ways that are consistent with relevant legislation and serve the public good”. (Trustworthiness pillar, T6 Data governance)

To comply with this and with the Data Protection Act of 2018, and to maintain the trust and co-operation of those who use Electronic Monitoring statistics, the following provisions have been put in place:

• private information collected by the Ministry of Justice is stored in line with Ministry of Justice data security policies;
• electronic data are held on password-protected networks;
• all new staff undergo Ministry of Justice security vetting before receiving access to data systems; and
• all staff undertake mandatory training on information responsibility annually.

Three types of disclosure risk are considered in relation to Electronic Monitoring statistics: general attribution, identification (including self-identification) and residual through combination of sources. Assessment of the risk of disclosure considers the following:

• level of aggregation (including geographic level) of the data;
• size of the population;
• likelihood of an attempt to identify; and
• consequences of disclosure.

As a result, the number of monitored individual counts of 2 or fewer are suppressed. This is to prevent the disclosure of individual information.

Publication frequency

In May 2024, responsibility for delivering electronic monitoring services transferred from Capita to Serco. During this transition, data was compiled from multiple sources. To ensure that the statistics continued to be produced to a high standard, the publication of electronic monitoring statistics was paused while processes were updated to reflect the new data source and to establish robust data quality assurance procedures.

This release represents the second publication since the contractual change, and the first official statistics publication following the pause.

Revisions

Figures for the most recent quarter should be treated as provisional, and all other data can generally be considered final. However, we are still embedding improvements to the data processing and as part of the continuous improvement process, minor processing changes may make small changes to the historical figures. Any significant planned or potential future processing changes will be noted in the release prior to their introduction. However, any significant errors will be corrected in line with the Code of Practice for Statistics.

In accordance with Principle 2 of the Code of Practice for Statistics, the Ministry of Justice is required to publish transparent guidance on its policy for revisions. A copy of this statement can be found here.

The three reasons specified for statistics needing to be revised are changes in sources of administrative systems or methodology changes, receipt of subsequent information, and errors in statistical systems and processes. Each of these points, and its specific relevance to the Electronic Monitoring publication, are addressed below:

1. Changes in sources of administrative systems/methodology
The data within this publication comes from a variety of administrative systems. This technical document will clearly present where there have been revisions to data accountable to switches in methodology or administrative systems. In addition, statistics affected within the publication will be appropriately footnoted.

2. Receipt of subsequent information
The nature of any administrative system is that data may be received late. For the purpose of this criminal justice statistics publication, the late data will be reviewed on an annual basis but, unless it is deemed to make significant changes to the statistics released; revisions will only be made as part of the final release containing the calendar year statistics. However, should the review show that the late data has major impact on the statistics then revisions will be released as part of the subsequent publication.

3. Errors in statistical systems and processes
Occasionally errors can occur in statistical processes; procedures are constantly reviewed to minimise this risk. Should a significant error be found, the publication on the website will be updated and an errata slip published documenting the revision.

4. Contact details

For enquiries, comments or further information, please contact:

HMPPS Electronic Monitoring Performance
Youth Justice and Offender Policy
Ministry of Justice
10th Floor
102 Petty France
London
SW1H 9AJ

Email: ppas_statistics@justice.gov.uk

Alternative formats are available on request from ppas_statistics@justice.gov.uk

5. Annex A: Glossary of terms

Acquisitive Crimes	Theft, robbery or burglary offences specific to the acquisitive crime pilot
Alcohol Monitoring	A way of remotely monitoring and recording information on an individual’s alcohol consumption, using an electronic device
Alcohol Monitoring Services (AMS)	The organisation responsible for the delivery of Alcohol Monitoring devices, reporting to Probation of drinking events and tampers and provision of alcohol monitoring data
Court Bail Order	When an individual is awaiting a court hearing or trial and are released from custody until the hearing or trial but the conditions of their bail must be monitored with an electronic monitoring device
Court Sentence	When community orders or suspended sentence order requirements are imposed on an individual by the court requiring monitoring with an electronic monitoring device
Electronic Monitoring	A way of remotely monitoring and recording information on an individual’s whereabouts, movements and alcohol consumption using an electronic monitoring device
Electronic Monitoring device	May also be referred to as a tag, usually fitted to the individual’s ankle, through which data is collected
Electronic Monitoring Services (EMS)	The electronic monitoring field and service provider
Foreign National Offenders	Offenders who are not UK citizens
Licence	The period in which a prisoner is released from prison to serve the remainder of their sentence in the community
Licence Variation	A change to the conditions in a prison leaver’s licence after they have been released from custody so as better to manage them in the community
Location Monitoring	Satellite enabled (GPS) electronic devices
Order	All requests to the electronic monitoring service provider for a device to be fitted to an individual. Orders can be raised from Courts, Probation, Prisons and Home Office
Immigration Order	Foreign National Offenders released from Prisons or Immigration Detention under ‘Immigration Order Bail’ must be monitored by an electronic monitoring device or non-fitted device (NFD), along with other non-UK citizens subject to deportation proceedings, while awaiting deportation
Post-release Order	When an individual has been released from prison with a licence condition that is monitored with an electronic monitoring device
Specials	Offenders assessed as high or very high risk of serious harm and managed under Level 3 Multi-Agency Public Protection Arrangements (MAPPA) that have been accepted as one or more of the following: CPPC; serious organised crime cases triaged and accepted into the NSD; terrorist risk cases that have been triaged and accepted into the NSD ; those granted bail by the Special Immigration Appeals Commission (SIAC); those made subject to Terrorism Prevention and Investigation Measures (TPIMs); and those convicted for offences under the terrorism act or terrorism act related offences

6. Annex B: Electronic Monitoring timeline

Overview of Electronic Monitoring policy changes:

Date	Summary
Nov 2018	National rollout of GPS devices begins
Oct 2020	Alcohol monitoring devices launched in Welsh courts
Dec 2020	GPS devices introduced for the immigration cohort
Mar 2021	Alcohol monitoring devices expanded to English courts
Apr 2021	Acquisitive crime cohort launched for eligible prison leavers released on licence in 6 Police Force Areas
Aug 2021	Immigration cohort expanded to non-UK citizens subject to deportation proceedings
Sep 2021	Acquisitive crime cohort expanded to 19 Police Force Areas
Nov 2021	Alcohol monitoring for prison leavers launched in Welsh pathfinder prisons
Jun 2022	Alcohol monitoring for prison leavers expanded to England
Aug 2022	Immigration cohort expanded to Scotland
Aug 2022	Electronic monitoring as Licence Variation pilot launched in 1 probation region
Oct 2022	Acquisitive crime cohort eligibility expanded to offenders who have received a custodial sentence of 90 days or more and been released on licence
Nov 2022	Non-fitted devices introduced for the immigration cohort
Dec 2022	Immigration cohort expanded to Northern Ireland
Mar 2023	Electronic monitoring as Licence Variation pilot expanded from 1 to 5 probation regions
Jul 2023	GPS trail monitoring pilot for Youth Rehabilitation Orders with Intensive Supervision and Surveillance launched in 4 regions
Aug 2023	Launch of Domestic Abuse Perpetrators on Licence (DAPOL) project in 2 probation regions
Dec 2023	Immigration bail pilot to non-FNO persons entering the UK via dangerous and unnecessary routes concludes
May 2024	Contract provider changes from Capita to Serco