HM Revenue and Customs (HMRC) has sent more than 81,000 letters over the past year, warning cryptocurrency holders they may owe capital gains tax. A Freedom of Information (FOI) request revealed that the number of letters issued by the tax authority has almost tripled since 2024.
In the 2025-26 financial year, HMRC sent 81,172 warning communications to crypto investors suspected of underpaying tax. This compares to 27,714 in the 2023-24 financial year.
Investors could face fines or prosecution if they do not declare profits from selling cryptocurrency, even when exchanging one digital currency for another. HMRC suspects significant unpaid capital gains from the period between December 2022 and October 2025, during which Bitcoin's price rose from approximately £14,000 to £90,000, despite a recent fall to around £48,000.
New powers, expected to be granted to HMRC next year, will enable easier targeting of wealthy crypto investors. From March 2027, cryptocurrency platforms in numerous countries outside the UK will be required to share customer information with tax authorities. HMRC estimates these changes could help raise up to £315 million by April 2030.