CARF reporting hub — what UK crypto firms send HMRC
Quick answer: In-scope cryptoasset service providers collect customer and transaction information from 1 January 2026. The first UK reports cover calendar year 2026 and are due by 31 May 2027. HMRC also receives information through international exchange. CARF does not calculate your liability or replace your own tax return.
CARF is the international standard the UK adopted so tax authorities can share crypto transaction data. This hub explains what UK service providers must collect from January 2026, when reports reach HMRC, and what you must still do yourself.
Which UK firms must report under CARF
Reporting status depends on the provider’s activities and UK connection under the CARF rules. FCA registration is not the test by itself. Providers should use HMRC’s reporting guidance; a user should expect identity and tax-residence checks and retain their own records.
What data providers collect from you
Expect requests for legal name, address, date of birth, tax identification (NINO where UK-resident), and confirmation of tax residence. For entities: company number and controlling persons. Providers must keep this accurate — update your profile after moving home or changing name.
What gets reported to HMRC
Providers report identifying information and prescribed transaction information, including aggregates by cryptoasset and transaction category. A transfer to a personal wallet may appear in provider records without itself creating a taxable disposal. Reconcile the underlying events rather than treating reported gross values as taxable profit.
Timeline: 2026 to 2028
1 January 2026: data collection begins. Throughout 2026: providers log reportable transactions. By May 2027: first CARF reports submitted to HMRC for calendar 2026. 31 January 2028: your online Self Assessment deadline for tax year 2026/27 — align your records with what providers reported.
Two reporting clocks
A provider’s calendar year is not your UK tax year
Keep both date ranges in your records. Provider reporting does not replace your own calculation or return.
Read the diagram as text
- CARF. 1 Jan → 31 Dec. Provider reporting follows the calendar year.
- UK TAX. 6 Apr → 5 Apr. Individual tax records follow the UK tax year.
Source: HMRC CARF reporting guidance
Self-custody, DeFi and foreign exchanges
HMRC can receive information from overseas reporting jurisdictions as well as UK providers. A self-hosted wallet does not remove tax obligations; transfers between providers and that wallet can leave an evidence trail. DeFi arrangements need their own tax analysis. Keep the full history wherever you transact.
If your return does not match CARF data
HMRC may open enquiries if declared gains differ materially from provider reports. Keep CSV exports, software audit trails and wallet logs. Correct errors via amended return or disclosure service before HMRC contacts you.
Start by rebuilding and reconciling the transaction history so each difference can be explained.
Consumer rights and privacy
Providers must explain CARF in privacy notices. You cannot opt out of statutory reporting by closing an account if transactions already occurred. GDPR still applies to how firms store your data.
Frequently asked questions
Will CARF tell me how much tax to pay? +
No. CARF is information exchange. You calculate tax using pooling rules and file Self Assessment.
I only use a hardware wallet — does CARF affect me? +
Self-custody does not exempt you from tax. A provider can report transfers involving your wallet, and overseas information may reach HMRC through exchange arrangements.
What if I forgot to declare old years? +
Check HMRC’s cryptoasset disclosure service and the applicable correction route. The outcome depends on the facts, timing and behaviour; voluntary disclosure does not guarantee a particular penalty.