HMRC finds value in ‘big data’ after bringing in extra £4.6billion
HMRC has increased its tax take via Connect by more than a third. iStock/Getty Images
08 Oct 2025, 9:39 am
Investigations based on HM Revenue and Customs’ big data system generated an extra £4.6 billion in tax in the last year – up more than a third from the previous period.
The Connect system uses data from a wide range of financial sources to analyse tax returns and detect potential evasion.
HMRC, in a freedom of information request to Pinsent Masons, said it generated on average £3.4bn in additional annual yield from Connect cases, with the 2024-25 tax year generating approximately £4.6bn.
Connect, which was introduced in 2010, has grown in scale over the last 15 years to become one of the largest datasets held by the UK government.
It has now become a key part of tax investigations, with around 4,300 HMRC staff now using it.
Ian Robotham, a tax expert at Pinsent Masons, said the database gave the revenue body access to more resources than would normally be possible to delve through.
“HMRC has spent time building up the amount of data sources that it can access and analyse,” he said.
“The algorithms that it uses allows HMRC to spot anomalies that would otherwise go unnoticed by the human eye.”
“With thousands of HMRC staff now using Connect, taxpayers are facing a level of oversight that would have been unthinkable just a few years ago.”
The increasing scale of the Connect system allowed HMRC to conduct more than half a million cases in the last year alone.
HMRC has also confirmed a partnership with a US data analytics firm, which is expected to see even more sophisticated AI applied to HMRC’s data
Contact an adviser
