What CARF Actually Is
The Cryptoasset Reporting Framework is the OECD’s international system for tax transparency on crypto, modelled on the Common Reporting Standard (CRS) that has covered bank accounts for over a decade. More than 40 jurisdictions signed up to the initial phase. The UK activated CARF on 1 January 2026. From that date, Reporting Crypto-Asset Service Providers (RCASPs) began collecting standardised information from their users, ready to report it to HMRC.
What Providers Are Collecting
From 1 January 2026, any crypto provider you use must collect your name, address, date of birth, tax residence and tax reference number. Refuse to provide the information and the provider can be fined, and HMRC has the power to issue a £300 fine on the individual. The providers also record transaction data (buys, sells, swaps, cross-transfers) and wallet information, and they will report a summary annually to HMRC.
When HMRC Gets The Data
The data collection started 1 January 2026 but the first reports to HMRC are not due until 31 May 2027, covering the 2026 calendar year. From 2027, HMRC will also begin exchanging the information automatically with tax authorities in other CARF countries, including EU member states, Channel Islands and dozens more. Major crypto hubs like the UAE, Hong Kong, Singapore and Switzerland join the exchange from 2028. The US follows in 2029.
What HMRC Already Has
CARF is not the start of HMRC’s crypto data. It is an escalation. Coinbase, the UK’s largest registered digital asset company, has shared data on UK customers holding £5,000 or more since around 2021. Other exchanges have provided data under various information-sharing arrangements. HMRC used that existing data to send 65,000 nudge letters to suspected crypto non-compliers in 2024/25, trebling the previous year’s figure. The people who thought they were invisible were not.
How Crypto Is Actually Taxed
For most UK investors, crypto gains are Capital Gains Tax, currently 18% (basic rate) or 24% (higher rate) on gains above the £3,000 annual exempt amount. Heavy trading can be classified as trading income, which pulls it into income tax rates plus National Insurance. Staking rewards, mining rewards and airdrops are income at the point of receipt. Buying, selling, swapping between crypto, converting to fiat, spending crypto on goods or services all count as disposals for CGT purposes.
The Voluntary Disclosure Facility
HMRC opened a dedicated voluntary disclosure facility for undeclared crypto gains made before April 2024. Coming forward voluntarily produces a materially better penalty position than waiting for HMRC to find you via CARF data in 2027. Once HMRC contacts you first, any disclosure is treated as prompted and the penalty range moves up. If you know you have undeclared crypto activity, the window to fix it on your terms is now, not next year.
Getting Ahead Of The Data
The first CARF reports land at HMRC in May 2027. That gives investors roughly 18 months to get their historic position clean and their current-year reporting right. A specialist accountant can reconstruct your transaction history from exchange exports, calculate the tax position accurately, and either file the correct returns or handle the voluntary disclosure. Our self assessment service handles crypto reporting alongside trading and self-employment income, and doing this properly now costs a fraction of fixing it after HMRC opens an enquiry.
