CARF reporting hub — what UK crypto firms send HMRC
Quick answer: UK cryptoasset service providers in scope must collect customer identity and transaction data from 1 January 2026 and report annually to HMRC. First reports cover calendar year 2026, due by May 2027. CARF does not calculate your tax — you keep records and file Self Assessment. Non-UK or self-custody activity is not reported by UK firms but may still be taxable.
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
HMRC guidance covers cryptoasset service providers established or operating in the UK that provide exchange, transfer, or safekeeping services to UK-resident customers. FCA MLR-registered exchanges typically fall in scope once CARF applies. Pure software wallets with no custodial service may be out of scope — but your tax duties remain.
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
Annual reports include aggregate and transaction-level information: acquisitions, disposals, transfers, and sterling equivalents where available. Reportable transfers may include movements to external wallets (Travel Rule overlaps). HMRC uses this to risk-assess Self Assessment returns — not to issue automatic assessments for most individuals.
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.
Self-custody, DeFi and foreign exchanges
CARF covers UK service providers. Holding keys yourself, using overseas exchanges without UK nexus, or pure on-chain DeFi may not appear on a UK provider CARF report — but HMRC still expects accurate declaration if you are UK-resident and taxable. Keep wallet exports and chain analytics.
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.
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? +
Not directly unless you also use a UK in-scope exchange. You still report taxable disposals.
What if I forgot to declare old years? +
Use HMRC's digital disclosure service for cryptoassets. Penalties are lower for voluntary disclosure.