CARF: The Crypto-Asset Reporting Framework UK Implementation (2026)

The Crypto-Asset Reporting Framework (CARF) is a global reporting standard created by the OECD, and the UK has committed to implementing it from 1 January 2026. Starting that date, UK-based crypto exchanges, brokers, and custodial wallet providers must collect information about their users — your name, address, tax residency, and transaction history — and report it annually to HMRC.

This is the moment crypto privacy ends. From 2027 onwards, HMRC will hold systematic data on every user of a regulated UK crypto firm, and they will cross-check it against your Self Assessment return. File accurately, because the tax authority will now have independent information about your activity — not just what you choose to tell them. This guide covers the framework's scope, timeline, what data is collected, and what it means for your compliance.

What is the Crypto-Asset Reporting Framework (CARF)?

CARF is an international standard, agreed by the OECD and endorsed by the G20, that requires Reporting Crypto-Asset Service Providers (RCASPs) — effectively exchanges, brokers, and custodial platforms — to identify their users and report on specified cryptocurrency transactions.

The UK's implementation builds on the OECD framework and mirrors similar rules that already apply to banks (the Common Reporting Standard for financial accounts). The purpose is to give tax authorities visibility of crypto activity so they can detect unreported income and capital gains, and support taxpayers in meeting their obligations.

It is not a blanket ban or block on crypto. It is a reporting regime: if you use a UK-regulated exchange, your activity becomes knowable to HMRC. If you use an unregulated or offshore platform, HMRC will not have direct access, but they may receive data through international co-operation agreements, and you are still liable to report your gains on your Self Assessment return regardless.

When does CARF start in the UK?

The framework comes into force on 1 January 2026. From that date, all UK-based in-scope crypto service providers must begin collecting standardised information about their users and their transactions.

The first reporting period covers the 2026 calendar year (1 January to 31 December 2026). Firms must submit their first annual report to HMRC between 1 January and 31 May 2027 — that is, by the end of May 2027, HMRC will hold 12 months of transaction data on anyone who traded on a UK platform during 2026.

Before the first report is submitted, firms must register with HMRC's online service by 31 January 2027 and notify their users that personal and transaction data will be reported. So if you use a UK exchange, expect a notification during early 2027 explaining what information will be shared.

What data will be collected and reported about me?

CARF requires providers to collect and report two categories of information: user identification and transaction data.

User identification includes your full name, date of birth, address, country of tax residence, and a tax identification number. For a UK resident, this is typically your National Insurance number or Unique Taxpayer Reference (UTR). The provider must perform due diligence to verify this information.

Transaction data includes details of reportable cryptocurrency activities:

- Crypto-to-fiat exchanges: when you sell or convert crypto into a traditional currency (e.g., selling Bitcoin for pounds sterling).

- Crypto-to-crypto exchanges: when you swap one digital asset for another (e.g., trading Bitcoin for Ethereum).

- Transfers: movements of crypto to external addresses (including transfers to your own wallets), airdrops, staking rewards credited to your account, and certain other transfers.

For each transaction, the provider reports the type of transaction, the date, the amount of crypto involved, the fair market value in pounds sterling at the time of the transaction, the type of asset (Bitcoin, Ethereum, stablecoin, etc.), and the counterparty information if relevant.

The provider does not report on every single keystroke; they report on an annual aggregated basis, showing the total picture of your activity during the year.

Who is in scope? Which providers have to report?

UK-based Reporting Crypto-Asset Service Providers (RCASPs) are in scope. These include:

- Centralized exchanges (e.g., Binance UK, Kraken UK, Coinbase UK if they hold customer assets or facilitate transactions in the UK).

- Brokers and dealers that facilitate crypto transactions for customers.

- Custodial wallet providers (services that hold crypto on your behalf).

- Other financial institutions that offer crypto services if they meet the legal definition of an RCASP.

The precise list of in-scope providers will firm up as the regime starts — more firms come into scope as they become regulated or apply for permission to operate in the UK.

Decentralized exchanges (DEXs), self-hosted wallets, and unregulated foreign platforms are generally not subject to CARF reporting in the UK (though some may face regulatory pressure in future). However, if you use an unregulated platform, you are still required to report your capital gains and income on your Self Assessment return — the absence of a provider report does not excuse you from filing accurately.

Also note: you cannot offset the risk of non-reporting by using a foreign exchange. Under international data-sharing agreements (from 2027 onwards), HMRC will receive CARF data from other countries on any UK resident who uses a foreign provider that is in scope in that country.

Does CARF mean HMRC will know about my crypto activity?

Yes — for anyone using a UK-based RCASP, HMRC will eventually have your data.

From 31 May 2027 onwards, HMRC will hold a report on you (if you traded in 2026), including your identity, tax residency, and your transaction history for that year. From that point, HMRC can cross-check what you report in your Self Assessment return against the provider's report.

From 2027 onwards, data on UK residents who used foreign RCASPs will also be available to HMRC through automatic exchange of information with other tax authorities that have adopted CARF. So even if you used a foreign exchange, HMRC may still receive data about you — the timeline depends on when that country implements CARF and how their information exchange system works.

The practical implication is simple: filing inaccurate or missing information on your Self Assessment is now riskier than ever. If your exchange report shows £50,000 in proceeds and you reported £30,000, or you did not file at all, HMRC will spot the discrepancy.

This also means HMRC is increasingly likely to send "nudge" letters to taxpayers whose reported gains do not match exchange data. You can respond to these letters by correcting your return or explaining any legitimate discrepancy (e.g., losses from a different platform, or a clerical error).

What is DAC8, and how does it relate to CARF?

DAC8 is the European Union's implementation of the OECD CARF framework. The EU's Directive applies the same reporting rules across EU countries, with EU member states required to transpose it by 31 December 2025 and apply it from 1 January 2026 — the same date as the UK.

The key difference is scope: DAC8 extends beyond the EU's own service providers. EU rules require reporting on any EU resident, even if they use a crypto service provider based outside the EU. This makes DAC8 broader than the plain OECD CARF, which does not have this extraterritorial reach.

For UK users, the relevance is this: if you use a European crypto exchange, that firm may be subject to DAC8 reporting, and if you are a UK resident, the data might be shared with HMRC under a bilateral information exchange agreement. The UK and EU have not (as of June 2026) formally agreed to automatic exchange, but discussions are ongoing and future co-operation is likely.

In practical terms, treat any CARF-compliant provider — UK or foreign — as one where HMRC may eventually see your data.

What should I do to stay compliant with CARF?

1. Keep clear records. Save all transaction data from your exchange, wallet, and DEX activity. If a provider reports incomplete or inaccurate information to HMRC, you may need to evidence what you actually did to correct the record. Our free calculator helps you compile this data into a proper tax summary.

2. File your Self Assessment accurately and on time. Report all capital gains and income from crypto in the SA108 boxes (13.1–13.8 for capital gains, and the relevant income boxes for staking, airdrops if taxable, etc.). Do not rely on "the provider might not report this" — assume HMRC will see it.

3. Pay any tax due by 31 January (the Self Assessment deadline). HMRC will begin chasing unpaid tax more aggressively once CARF data is available to them.

4. Watch for notifications from your exchange. By late 2026 or early 2027, you may receive a letter from your provider explaining that they will report your data to HMRC. This is not a threat — it is a legal notification. Read it, check the name and address on file, and correct any errors.

5. If you see discrepancies, act early. If you believe your provider's report contains errors (e.g., a failed transaction that was recorded anyway, a withdrawal that was double-counted), contact your provider and ask them to investigate and correct the record before they submit to HMRC.

6. Use a UK-native tax tool. Our free calculator and SA108 guide are built for the UK tax year and the CARF reality. They help you reconcile your activity, claim your annual exempt amount, and file accurately.

What penalties apply if a provider does not report correctly?

Penalties are imposed on providers, not directly on you — but they create an incentive for providers to get the data right.

A provider that fails to report, submits late, or provides inaccurate or incomplete information to HMRC faces a penalty of up to £300 per user. Further penalties can apply for failing to apply due diligence, keep records, obtain valid user self-certifications, or notify users.

If a provider's report is wrong and it affects your tax bill, you have options: you can correct your own Self Assessment and provide evidence of the error, or you can ask the provider to file an amended report with HMRC. HMRC will generally accept evidence that shows the discrepancy was a clerical error by the provider, not tax evasion by you — but the burden is on you to provide it.

The key: do not expect a provider penalty to automatically remove an error from HMRC's view. Verify your own data, file it correctly, and keep records.

Frequently asked questions

What if I use a DEX and do not hold crypto on an exchange? A DEX transaction is not automatically reported to HMRC by the DEX (most DEXs do not hold your data, you transact directly). However, you are still required to report it on your Self Assessment. HMRC may also trace your activity on-chain or see it if you eventually withdraw to an RCASP or exchange fiat on a regulated platform. File accurately.

What if I use a foreign exchange? If the foreign exchange is an RCASP in its country and that country has a CARF arrangement with the UK, HMRC will eventually receive data on you. Even if they do not, you must report the activity on your UK Self Assessment return. Capital gains are due regardless of where you trade.

Will HMRC see my losses as well? Yes. The provider will report your total transaction activity — trades that resulted in losses as well as gains. HMRC can then see your full picture, which is actually helpful if you have genuine losses to offset against gains. File a complete and accurate return, and the losses will be recognized.

What if my exchange goes bust before HMRC gets the report? If a provider ceases business before submitting the first report (unlikely but possible), HMRC has backup rules to collect the data from users or other sources. You are still required to report your activity on Self Assessment — the absence of a provider report does not excuse you.

Can I claim the gains are mine, but the losses are my partner's? No. CARF reports individual user activity. If you held crypto in your own exchange account, the gains and losses on that account are taxed to you. Transferring crypto to a spouse (or vice versa) between accounts is a reportable transaction (a transfer), and if it is on the same exchange it will be visible. Use the spouse transfer rules correctly (no-gain-no-loss for transfers between spouses, s.58 TCGA 1992), but do not attempt to hide or reassign gains retroactively.

I have already filed my 2025/26 return. Will CARF cause it to be amended? If your provider's first CARF report (due 31 May 2027) shows activity that differs from what you reported for 2025/26, HMRC may issue a "nudge" letter or demand a correction. Correct it promptly, with evidence. If you paid less tax than you should have, you will owe the difference plus interest. If you paid more, HMRC may refund it, but only if you ask and provide evidence.

Next steps

Verify your 2025/26 tax position now. Use our free calculator to compile your full transaction history, calculate your gains, and check that you have claimed your annual exempt amount correctly. File your Self Assessment by 31 January 2027 with the right figures.

Prepare for 2026 onwards. From 1 January 2026, assume every trade on a UK platform is being recorded. Keep detailed records. At the end of each calendar year, export your transaction history and reconcile it to your tax calculations.

Check the SA108 guide. Our detailed walkthrough of SA108 boxes shows exactly where to report gains, losses, disposals, and proceeds, and how to align with HMRC's expectations.

Read about your exchange's reporting obligations. When your exchange publishes its CARF notification (expected late 2026 or early 2027), read it and check that your account name and tax residency are correct. Report any errors to the exchange's compliance team.

Understand your cost basis. The most common source of errors is getting your cost wrong. Refresh yourself on how the Section 104 pool works — that is your cost for the purposes of both your tax return and HMRC's cross-check against the provider's report.

Sources

• GOV.UK — Implementation of the Cryptoasset Reporting Framework (CARF)
• GOV.UK — Domestic reporting of UK resident cryptoasset users under CARF
• GOV.UK — Check if you'll need to report cryptoasset data to HMRC
• GOV.UK — Reporting cryptoasset user and transaction data
• OECD — Crypto-Asset Reporting Framework (CARF) overview
• OECD — CARF and amended CRS: IT format and interpretative guidance (October 2024)
• European Commission — DAC8 (EU's CARF implementation, Directive on administrative co-operation)
• Finance Act 2024 — UK legislation enabling CARF
• HMRC — CRYPTO22100 — Cryptoassets manual: what is a disposal
• GOV.UK — Self Assessment deadlines and how to file
• CryptoCGT — SA108 boxes 13.1–13.8 detailed guide
• CryptoCGT — Section 104 pool cost basis guide
• CryptoCGT — Free crypto tax calculator