CARF: What UK Crypto Users Need to Know in 2026

The Crypto-Asset Reporting Framework (CARF) is the OECD's new standard for cross-border reporting of crypto activity, modelled on the Common Reporting Standard for bank accounts. The UK adopted CARF into domestic law from 1 January 2026 (The International Tax Compliance (Crypto-Asset Service Providers) Regulations 2025). Here is what it actually means for a UK crypto user, without the acronym soup.

Who has to report

Reporting Crypto-Asset Service Providers (RCASPs). In practice this covers:

- **Centralised exchanges** operating in or from a CARF-participating jurisdiction — Coinbase, Kraken, Binance, Bitstamp, Gemini and all their peers with UK-resident users. - **Custodians** holding crypto for others, including some staking-as-a-service providers. - **Brokers** intermediating trades — including many DeFi front-ends where a UK-resident entity is doing the interfacing. - **NFT marketplaces** above certain thresholds.

Peer-to-peer DEX contracts (Uniswap smart contracts themselves) are outside CARF because there is no reportable entity. But on-chain activity remains publicly visible and can be traced by HMRC directly. See <a href="/blog/does-hmrc-know-about-crypto-uk">does HMRC know about crypto UK</a>.

What must be reported about you

RCASPs must collect and report:

- Your name, address, jurisdiction of tax residence, date of birth, and Tax Identification Number (National Insurance number for UK residents). - For each reportable year: - Aggregate gross proceeds and number of relevant transactions per asset for sales of crypto to fiat. - Aggregate gross proceeds and number of transactions per asset for crypto-to-crypto exchanges. - Aggregate gross proceeds and number of transactions per asset for transfers (outbound and inbound), including retail payments above the threshold (currently USD 50,000 for a single transfer). - Wallet addresses used for transfers.

This is aggregate data, not individual trade rows. But it tells HMRC how much you disposed of, in which assets, on which platform.

The self-certification requirement

Every reporting exchange must obtain a self-certification from you confirming your tax residence and TIN. This is why every UK-resident user of Coinbase, Kraken and Binance received a KYC refresh in late 2025 and early 2026. If you do not self-certify, the exchange must freeze your account or restrict trading.

**Providing a false self-certification is a criminal offence** under Regulation 22 of the 2025 Regulations, punishable by an unlimited fine on indictment or a fine up to level 5 on the standard scale (£5,000) summarily. Simply pretending you are non-UK-resident to escape reporting is a very bad idea.

Timeline

- **1 January 2026:** UK CARF Regulations in force. Exchanges begin collecting reportable data. - **31 May 2027:** first CARF report submitted to HMRC by RCASPs, covering the 2026 calendar year. - **31 May 2028:** second report, covering the 2027 calendar year. - **October 2027 onwards:** HMRC begins reciprocal exchange with 48+ CARF-participating jurisdictions. HMRC also receives data on UK-resident users of foreign exchanges (from jurisdictions that have adopted CARF).

What HMRC will do with the data

Two immediate use cases:

1. **Reconcile against Self Assessment.** If you told HMRC you had £2,000 of gains and Binance says you disposed of £150,000 of crypto, an enquiry is inevitable. 2. **Send nudge letters.** HMRC's nudge letter campaign (see <a href="/blog/hmrc-crypto-nudge-letter">HMRC crypto nudge letter</a>) is already active and will be sharpened by CARF data. The 2027 wave will be pre-populated with actual exchange data.

The absence of a CARF report does not mean HMRC cannot see the activity. Blockchain analytics contracts (Chainalysis, Elliptic, TRM) supplement the CARF data and can trace on-chain flows even for non-CARF-reporting exchanges and DeFi.

Jurisdictions participating in CARF

The initial group of 48 committed jurisdictions includes: all EU member states, the UK, Australia, Canada, New Zealand, Singapore, South Korea, Switzerland, the UAE, and the crown dependencies (Jersey, Guernsey, Isle of Man). Notably absent from the initial group: China, Russia, and some smaller offshore financial centres.

Using a non-participating exchange does not remove your UK tax liability. It only reduces the automatic data flow — HMRC can still trace on-chain activity to a wallet linked to a UK-CARF-reporting on-ramp.

Practical steps for a UK user

1. **Self-certify accurately.** Every exchange you use, correct tax residence, correct TIN. 2. **Reconcile your own records against what your exchanges will report.** Use <a href="/carf-check">/carf-check</a> to see the CARF-visible totals per exchange based on your imported data. 3. **File your 2026/27 Self Assessment on the arising basis, including all worldwide crypto activity.** UK residents are taxed on worldwide crypto — being on a non-CARF exchange does not exempt you. 4. **Keep records for six years** past the filing deadline, per HMRC standard record retention. 5. **If you have historic under-reporting**, seriously consider the <a href="/blog/hmrc-crypto-voluntary-disclosure-uk">HMRC voluntary disclosure route</a> before the first CARF report lands in May 2027. Disclosed penalties are much lower than discovered penalties.

What CARF does not do

- It does not change how you calculate your CGT. Section 104 pooling, same-day, 30-day matching, and the £3,000 AEA are all unchanged. See <a href="/blog/how-to-calculate-crypto-tax-uk">how to calculate crypto tax UK</a>. - It does not create new taxes. It is a reporting framework, not a tax. - It does not cover self-custody wallet-to-wallet transfers between addresses you control (these are not disposals, and the exchange sees them as ordinary withdrawals). - It does not exempt any DeFi activity from tax. On-chain activity is HMRC-visible even without CARF.

The bottom line

CARF closes the "HMRC does not know" gap. For 2026 and later years, assume HMRC will receive data on your exchange activity by May 2027, matched to your name and NI number via KYC. File accurately, keep records, and use <a href="/example-tax-report">the example tax report</a> to see what a clean SA108 output looks like.