The expansion of electronic tagging in England and Wales is being held up by concerns over public safety, according to a stark warning from the National Audit Office (NAO). The watchdog's report has highlighted significant flaws in the current system, which risks exacerbating overcrowding pressures on already strained prisons unless urgent improvements are made.
The number of individuals subject to electronic monitoring has more than doubled in five years, reaching 28,700 as of March this year. The government plans to increase this figure by a further 22,000 annually from 2027, as part of its strategy to manage offenders within the community and alleviate prison capacity issues. However, the NAO's findings suggest that thousands of individuals who should be monitored may not be.
The HM Prison and Probation Service (HMPPS) was reviewing approximately 8,900 cases – representing 24% of those required to be tagged – as of March this year to ascertain the number of unmonitored individuals. In contrast, the Ministry of Justice reported a lower figure of around 5,450 unmonitored cases. The discrepancy highlights concerns over data quality and oversight.
The NAO report specifically criticised Serco, an external contractor, for its early performance in electronic monitoring. Between August 2024 and July 2025, individuals were not tagged promptly, and officials were not notified of potential breaches in a timely manner. Although Serco's performance has reportedly improved since then, the backlog of visits to fit, check or remove tags surged to a peak of 7,000 in October 2024 before reducing to under 400 by November 2024.
Furthermore, an estimated shortfall of around 2,200 probation staff as of March this year raises questions about the system's ability to scale up safely. The NAO concluded that any further expansion of electronic monitoring would be neither efficient nor effective unless the Ministry of Justice and HMPPS collaborate with partners to address existing weaknesses in governance, data quality and system-wide inefficiencies.
Gareth Davies, head of the NAO, stated that electronic monitoring is crucial for managing prison pressures but is currently not working effectively, thereby creating risks to public protection. The government has committed up to £175 million to fund this expansion over the period 2026-29. Sir Geoffrey Clifton-Brown, Chair of the Public Accounts Committee, echoed the NAO's concerns, highlighting that the government lacks certainty on the number of unmonitored individuals and its capacity to respond swiftly to breaches.
Pia Sinha, Chief Executive of the Prison Reform Trust, also expressed concern, warning against viewing electronic monitoring as a "panacea" for prison overcrowding without addressing wider systemic pressures and investing in probation services. Her comments highlight the need for urgent action to address the flaws in the current system and ensure that public safety is not compromised by further expansion.