Approximately 1,200 HMRC tax investigations a year could qualify for the new enhanced whistleblowers rewards (based on the number of investigations that would have qualified last year), says multinational law firm Pinsent Masons*.
Data provided by HMRC to Pinsent Masons shows that last year over 1,200 tax investigations collected enough extra tax to potentially qualify for what is called the “Strengthened Reward Scheme”, which officially came into effect on 26 November 2025.
Under the new scheme, whistleblowers who help HMRC recover at least £1.5m in unpaid tax can be rewarded with between 15% and 30% of the tax collected. Tax investigations that yield such large amounts of money usually target large companies, wealthy individuals or avoidance schemes.
In FY2024, the US scheme on which HMRC’s is based on (the IRS whistleblower scheme) gave out $123.5m in rewards across 105 awards and the reward scheme collected over $7 billion in extra tax for the US.
“One of the most obvious sources of this information is going to be insiders working within a company that they blow the whistle on. So, if you are a large business then you need to be aware of this and make sure you have your house in order.”
Hinesh Shah, Partner at Pinsent Masons
“HMRC has introduced the Strengthened Reward Scheme as part of its wider efforts to tackle the UK’s persistent tax gap, estimated at over £59.2bn. The scheme seeks to strengthen tax compliance by financially incentivising whistleblowers who provide actionable intelligence relating to large-scale tax evasion and avoidance.
“The US system recovers hundreds of millions in extra tax every year and HM Treasury will be hoping for that kind of result. If you are a corporate you should also make sure that all your own internal whistleblowing systems work properly and that your staff trust your whistleblower system.”
“Often insiders only report malpractice to outside agencies, like HMRC, once they feel that their attempts to highlight the problem internally have been frustrated.”
According to HMRC its overall compliance yield from tax investigations was £48 billion. However, it is under pressure to improve on that and more successful investigations launched on whistleblower information could help.
Hinesh Shah says the scheme should make HMRC investigations quicker and more effective because whistleblowers can provide very detailed information on where tax underpayments may have occurred and help provide easy access to some of the paperwork needed for HMRC to build a case.
He says: “HMRC can spend years trying to prove a company has underpaid tax but the new scheme could cut that to months. Whistleblowers could point HMRC straight to the evidence it needs to make a successful case.”
* Research based on an FOI to HMRC showing that more than 1,200 tax investigations recovered more than £1.5m in tax year 2024/25.
