Crypto exchanges now report to HMRC: what CARF means for you

From 1 January 2026, crypto exchanges such as those you use to buy Bitcoin or Ethereum must collect your tax details and report your transactions to HMRC each year. This is the Cryptoasset Reporting Framework, or CARF. The first reports, covering the whole of 2026, are due with HMRC by 31 May 2027, so any gains you have not reported will be easier for HMRC to spot.

What is the Cryptoasset Reporting Framework?

CARF is an OECD standard that makes crypto service providers report their users’ details and transactions to tax authorities. The UK put it into law through The Reporting Cryptoasset Service Providers (Due Diligence and Reporting Requirements) Regulations 2025 (SI 2025/744), made on 24 June 2025 and in force from 1 January 2026.

The rules cover any business with a UK link that runs a trading platform or exchanges cryptoassets for fiat currency, such as pounds, or for other cryptoassets. Providers must check who their users are, report to HMRC and tell users that their details will be reported.

Does CARF apply to UK users?

Yes. The UK applies CARF to UK residents using UK providers, as well as to users who are tax resident in other countries that have signed up.

HMRC’s guidance for users says: “HMRC will use your information to link your cryptoasset activity to your tax record.” Under regulation 8 of SI 2025/744, providers must also tell you that your information may be passed to the tax authority of another CARF country.

What information do you have to give?

You must give your details to every provider you use, including providers outside the UK.

HMRC’s Cryptoassets Manual at CRYPTO10410 adds that a provider may refuse further services if you do not give the details.

What is the £300 penalty?

GOV.UK says that if you give inaccurate details, or none, to a UK service provider, you could get a penalty of up to £300. Regulation 13 of SI 2025/744 sets this cap where the failure is deliberate or due to a lack of reasonable care. Providers outside the UK follow their own country’s rules.

Providers face their own penalties. HMRC’s reporting guidance, updated on 2 November 2026, says HMRC may charge up to £300 per user if a provider does not report, reports late or sends inaccurate data.

When does HMRC get the data?

The timetable runs on calendar years, not tax years.

1. 1 January 2026: providers start collecting user details and recording transactions.
2. By 31 January 2027: providers must tell each reportable user that their information will be reported.
3. By 31 May 2027: first report to HMRC, covering 1 January to 31 December 2026.
4. By 31 May each year after that: a report for the previous calendar year.

The reporting guidance notes the online submission service is not yet live. HMRC says it will update the guidance when it is.

Why does this matter for your 2025-26 return?

The 2026 report covers the last three months of the 2025-26 tax year. Disposals made from 1 January to 5 April 2026 belong on the 2025-26 Self Assessment return, due by 31 January 2027. HMRC will receive that data four months later, by 31 May 2027.

The rest of 2026, from 6 April, falls in 2026-27. That return is due by 31 January 2028.

When do you pay tax on crypto?

You may owe Capital Gains Tax whenever you dispose of crypto. HMRC’s cryptoasset tax guidance, updated on 5 October 2026, lists:

• selling tokens for money
• exchanging one token for another
• using tokens to pay for goods or services
• giving tokens away, except to a spouse, civil partner or charity

Each token type goes into a pool with an average cost. Special rules apply to tokens bought on the same day or within 30 days after a sale. For 2026-27, CGT rates are 18% on gains within the basic rate band and 24% above, after the £3,000 annual exempt amount.

Since 2024-25, the Self Assessment return has a separate cryptoasset section, completed in pounds sterling. Our guide to Capital Gains Tax on crypto and NFTs has worked examples, and the Capital Gains Tax calculator estimates the bill.

What to do now

1. Give your details. Answer any request from your exchange, using your NI number or UTR.
2. Download your transaction history. Get it from every exchange and wallet now, while accounts are open.
3. Keep your own pool records. HMRC says exchange reports do not track pooled costs, so you need your own.
4. Check your 2025-26 disposals. Include anything sold or swapped between 6 April 2025 and 5 April 2026 on the return due 31 January 2027. See how to report and pay CGT.
5. Fix earlier years. HMRC’s guidance points to its Cryptoasset Disclosure Service for unpaid tax from past years. Our guide to HMRC nudge letters explains what happens if HMRC writes first.

Frequently asked questions

What is CARF?

The Cryptoasset Reporting Framework is an OECD standard that makes crypto exchanges report users’ details and transactions to tax authorities. In the UK it has applied since 1 January 2026.

Do UK crypto exchanges report to HMRC?

Yes. Under SI 2025/744 they report UK users to HMRC each year, with the first report for 2026 due by 31 May 2027.

What happens if I do not give my exchange my National Insurance number?

GOV.UK says you could get a penalty of up to £300, and the provider may refuse further services.

Does CARF mean I owe more tax?

No. CARF changes what HMRC knows, not the tax rules. You owe Capital Gains Tax only on disposals with gains above the annual exempt amount.

Is the CARF report the same as my tax figures?

No. The report covers a calendar year, while your return covers 6 April to 5 April, and it does not track your pooled costs.