The UK's HM Revenue & Customs (HMRC) has issued nearly 65,000 advisory letters to citizens suspected of not paying taxes on cryptocurrency earnings. This marks a significant increase from the 8,329 letters sent in the 2021/2022 tax year, reflecting a 134% rise in suspected non-compliance. The letters aim to prompt taxpayers to address any outstanding tax obligations before formal investigations commence. The surge in alerts comes as many crypto investors remain unaware of their tax responsibilities, potentially leading to substantial debts. HMRC is enhancing its data collection efforts, obtaining information directly from crypto exchanges and preparing to implement the Crypto-Assets Reporting Framework (CARF) in January 2026 to further track crypto-related tax compliance.