This figure, revealed in a freedom of information request made by Pinsent Masons, represents a 35% increase on the system’s average annual yield of £3.4bn.

Introduced in 2010, Connect analyses and links vast amounts of information from multiple sources, including bank records, online marketplaces, and potentially social media, to identify financial discrepancies. According to HMRC, the system builds data networks to find “patterns and links… that would be impossible for the human eye to spot”. The authority stressed, however, that human insight always makes the final judgment in any investigation, Financial Times reports.

The extra £4.6bn collected is a significant contribution towards closing the UK’s “tax gap” – the difference between tax owed and tax collected – which was estimated at £46.8bn for 2023-24. Ian Robotham of law firm Pinsent Masons, which made the FOI request, said the figures demonstrate the system is “working”.

Despite this success, HMRC faces criticism for data blind spots, particularly concerning the super-rich. A recent report from the House of Commons Public Accounts Committee stated that HMRC has “no overview of an individual’s total wealth” and struggles to accurately assess the tax liabilities of wealthy people.

Committee member Lloyd Hatton, a Labour MP, described HMRC’s estimates of the “wealthy tax gap” and “offshore tax gap” as “woefully inaccurate”.