HM Revenue and Customs sent over 81,000 letters warning holders of cryptocurrency that they may owe capital gains tax in the UK over the past year.

The number of letters was revealed via a Freedom of Information (FOI) request issued by UHY Hacker Young.

The letters show that cryptocurrency investors could face fines if they do not declare their cryptocurrency profits, through either the trade, selling, or exchanging of crypto.

These warnings come ahead of new rules which will empower HMRC to more easily go after crypto investors who may not be paying their capital gains tax in relation to crypto.

In the 2025-26 financial year, HMRC sent 81,172 letters warning crypto investors that they may have unpaid taxes, while in 2023-24, this number sat at just 27,714.

“We’re committed to helping people pay the right amount of tax, and the vast majority do,” an HMRC spokesperson said.

“We regularly send letters to educate, remind or prompt customers to review their tax affairs, including customers who use crypto assets.”

From 2027, new regulations will oblige cryptocurrency platforms to share information about their customers with HMRC in an effort to prevent tax evasion on profits made from crypto exchanges and sales.

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HMRC estimated that these changes could raise up to £315 million by April 2023, as it forces “crypto bros to pay their fair share of tax”.