The UK’s tax authorities are stepping up their monitoring of cryptocurrency transactions, sending significantly more warning letters to investors suspected of underreporting or avoiding taxes on their digital asset holdings. This crackdown is triggered by a surge in crypto ownership within the UK alongside growing market activity, prompting regulators to increase compliance measures. HM Revenue & Customs (HMRC) issued nearly 65,000 warning letters specifically regarding unreported gains in the 2024–25 tax year, an increase of over double compared to the previous year. This surge underlines the UK’s growing focus on crypto tax compliance as market participation expands. 65,000 warnings are more than a tenfold jump from the prior four years. HMRC has already dispatched over 100,000 such letters in the past few years, reflecting the rise in cryptocurrency adoption and its price increase.