UK watchdog warns electronic tagging expansion could leave offenders untracked

Watchdog warning

The National Audit Office has warned that the government’s planned expansion of electronic tagging in England and Wales could leave some offenders effectively untracked unless the current system is fixed first.

The report turns a policy designed to increase supervision in the community into a warning about delivery. The watchdog says the system already faces backlog pressures, data problems and shortages in probation staffing, raising doubts about whether it can safely absorb the larger caseload ministers want.

What the NAO found

The NAO said around 28,700 people are being electronically monitored, roughly double the level of five years ago. But it also said HMPPS was reviewing about 8,900 cases as of March 2026 to work out how many people who should have been tagged were not being actively monitored.

That review figure was described as about 24% of those required to be tagged. The Ministry of Justice has used a lower estimate, saying the number of unmonitored cases is around 5,450. The difference underlines the uncertainty the report says still surrounds the scale of the problem.

The watchdog also pointed to a probation staffing shortfall of about 2,200 people as of March 2026. It said that gap affects the wider system that has to manage breaches, check compliance and respond when tagging alerts need follow-up.

Expansion before fixes

The government announced a major expansion of electronic tagging in March 2026, with plans to tag about 22,000 people a year from 2027. It has also set aside up to £175 million for the expansion over 2026-29.

But the NAO said the programme would not be efficient or effective unless the Ministry of Justice and HM Prison and Probation Service fix the operational weaknesses first. In its view, scaling up the service before the current problems are resolved risks widening the gap between policy ambition and actual monitoring.

Backlogs and contractor performance

The report says early performance problems with Serco, the contractor involved in the tagging system, contributed to delays between August 2024 and July 2025. It says a backlog of tag-fitting visits peaked at 7,000 in October 2024.

By February 2026, Serco had reportedly met a 95% timeliness target for visits, but still fitted tags on only 62% of the people it visited within two attempts. That leaves open questions about how quickly the system can convert appointments into active monitoring in practice.

The NAO said those problems were part of the reason some offenders were left waiting for tags or were not being monitored as intended. It argues that the government needs a more reliable operational base before it can safely increase volumes.

Government response

The Ministry of Justice says it inherited a failing tagging system with record backlogs and says installation rates have risen by almost 50% since 2024. It also says it is investing £100 million in electronic monitoring and £700 million in probation.

That response sets up the central dispute in the report: the department says performance has improved and funding is in place, while the NAO says serious weaknesses remain in the system that would carry over into any larger rollout.

The government’s expansion plan is also part of a wider strategy to manage prison overcrowding by supervising more offenders in the community. That makes the integrity of the tagging system more important, because the policy depends on tags actually being fitted, monitored and enforced.

What happens next

The immediate next questions are whether the NAO publishes further detail on the 8,900 cases under review, whether the Ministry of Justice sets out a line-by-line rebuttal, and whether updated operational data narrows the gap between the official counts.

Parliamentary scrutiny is also likely. The report’s warnings about staffing, breach response and contractor performance give MPs and committees clear areas to probe, especially if the government wants to keep the expansion timetable intact.

For now, the watchdog’s message is straightforward: expand tagging only after the current system is stable enough to protect the public reliably.