HMRC sent 81,172 tax warning letters, emails and text messages to crypto investors in the 2025/26 financial year, about 25% more than the 64,982 issued in 2024/25 and nearly three times the 27,714 recorded in 2023/24, based on Freedom of Information figures obtained by UHY Hacker Young and reported by the BBC. The agency suspects some undeclared liabilities stem from gains as crypto prices rose between late 2022 and 2025, though it has not disclosed how much unpaid tax the campaign identified and a nudge letter does not automatically mean tax is owed or that a formal investigation has begun. Capital Gains Tax can arise on sales for fiat, token-to-token exchanges, crypto-funded purchases and most gifts, while mining, staking, employment and some DeFi receipts may create Income Tax obligations. Under the Cryptoasset Reporting Framework, UK service providers have collected customer details since January 2026 and must submit first reports on 2026 activity by May 31, 2027, measures HMRC estimates could raise up to £315 million by April 2030. Unpaid domestic tax can attract penalties of up to 100% plus interest, and taxpayers may correct earlier liabilities through HMRC’s Cryptoasset Disclosure Service.