UK CARF 2026: What HMRC Crypto Reporting Really Means

The UK Cryptoasset Reporting Framework started on 1 January 2026. It requires in-scope cryptoasset service providers to identify users and report tax-relevant activity, with the first 2026 reports due by 31 May 2027. This guide separates what CARF reports from what a UK tax calculation still has to reconstruct.

What CARF means in the United Kingdom

CARF stands for Crypto-Asset Reporting Framework. It is an OECD tax-transparency standard and is separate from the Common Reporting Standard (CRS). The UK implemented CARF through the Reporting Cryptoasset Service Providers (Due Diligence and Reporting Requirements) Regulations 2025. The rules took effect on 1 January 2026.

CARF requires an in-scope Reporting Cryptoasset Service Provider, or RCASP, to perform due diligence on users and report tax-relevant identity and transaction information. UK domestic reporting also brings UK-resident users of UK RCASPs into HMRC's dataset. Information about users resident in partner jurisdictions may be exchanged with the relevant foreign tax authority, while HMRC may receive UK-resident data from providers in participating jurisdictions.

This is an information-reporting regime. It does not create a new crypto tax, change the UK's Capital Gains Tax rules or replace Self Assessment. HMRC's CARF introduction expressly distinguishes the reporting framework from the rules that tax cryptoassets.

The correct UK CARF timeline

The decisive point for investors is that the first report covers calendar year 2026. It is wrong to describe it as a report for 2025/26. HMRC confirms the commencement and first filing date in IEIM8000050.

Which crypto businesses have to report?

The obligation is not limited to a short list of famous exchanges or to businesses described informally as “FCA-regulated exchanges”. An RCASP is generally a business that, as a business, either transacts relevant cryptoassets for users or provides a means for users to transact them. Exchanges, brokers and dealers can be in scope, but the precise result depends on the activity, relevant cryptoassets and the UK's nexus rules.

A provider can have connections to several countries and may report in only one under the hierarchy of nexus rules. Therefore, it is unsafe to state categorically that every Binance, Coinbase, Kraken or eToro transaction is reported by a UK entity. A UK resident may instead be reported to HMRC through a participating foreign jurisdiction. HMRC explains the provider and nexus tests in its RCASP scope guidance.

Self-custody software that merely lets a person hold keys is not automatically an RCASP. But a wallet application or platform that facilitates exchanges may be in scope. NFTs, stablecoins, utility tokens and security tokens can be relevant cryptoassets when the statutory conditions are met; central bank digital currencies and specified electronic money products are handled under the amended CRS instead.

What information must a crypto user provide?

From 2026, a service provider may request a CARF self-certification. An individual normally provides:

• full name and date of birth;
• home address and country of residence;
• jurisdiction or jurisdictions of tax residence;
• a tax identification number, such as a National Insurance number or Unique Taxpayer Reference for a UK resident, where applicable.

Entities provide their legal name, main address and relevant company or tax identification number. Certain entities must also identify controlling persons. HMRC says details must be accurate and warns that a person who deliberately or carelessly fails to provide a valid self-certification can face a penalty of up to £300. A provider may also decline further service. The current user requirements are set out in HMRC's cryptoasset user guidance.

What transaction information is reported?

A provider collects transaction-level facts such as the cryptoasset, transaction type, number of units and value. The annual CARF report then contains identification data and aggregated transaction information for each relevant cryptoasset and reportable category. It should not be described as a universal line-by-line tax statement.

Depending on the activity visible to the provider, reportable categories can include:

• acquisitions and disposals against fiat currency;
• crypto-to-crypto acquisitions and disposals, generally valued at fair market value;
• reportable retail payment transactions above the CARF threshold;
• transfers made by or for the user, including separate reporting for certain transfers to external wallet addresses.

HMRC explains the identity and transaction fields in IEIM8000515. For transfers to external wallets, HMRC IEIM8000585 requires a provider to report aggregated units and value in the relevant category and retain the address; HMRC's current guidance says the actual address is not part of the routine CARF submission, although HMRC may request retained records.

CARF reporting is limited to the provider's knowledge. If a provider sees only one side of a cross-platform transaction, it may report a transfer rather than invent the asset acquired elsewhere. This is one reason why a taxpayer's consolidated wallet history remains essential.

Why a CARF report is not a UK tax calculation

HMRC will not receive a “perfect copy” of a taxpayer's final gain calculation merely because CARF applies. CARF data is useful for compliance matching, but it does not by itself perform the UK's share-pooling calculation or determine the legal owner, transaction purpose and tax classification.

A correct UK crypto computation may still need to:

• combine every exchange and wallet held by the same beneficial owner;
• apply same-day matching, the following 30-day rule and the Section 104 pool in the correct order;
• distinguish transfers between the user's own wallets from disposals;
• separate capital disposals from mining, staking, employment or trading income;
• value events in GBP at the relevant time and document the source;
• carry historic pooled quantity and allowable cost into the tax year;
• identify lost access, gifts, DeFi transactions, derivatives and fees that need separate analysis.

The UK 30-day and Section 104 guide explains why provider-level totals cannot be copied directly into Capital Gains Tax figures. For multi-platform data, use the workflow in the UK exchange reconciliation guide.

CARF calendar year versus UK tax year

CARF reports by calendar year, from 1 January through 31 December. UK individuals normally calculate Self Assessment using the tax year from 6 April through 5 April. One CARF calendar report can therefore overlap two UK tax years, and one UK tax year can overlap two CARF reports.

Do not force the CARF total into a tax-return box. Use timestamps and GBP valuations to assign each taxable event to the correct UK tax year, then apply HMRC's pooling and income rules. The UK crypto tax guide covers the wider filing framework.

A 2026 notification can contain two tax years

Consider two unrelated token holdings, each sold in full, with no matching purchases or fees. A sale on 15 January 2026 has £2,000 proceeds and £1,200 allowable cost: an £800 gain in 2025/26. A sale on 15 May 2026 has £3,000 proceeds and £2,500 cost: a £500 gain in 2026/27. Both fall inside the provider's 2026 calendar reporting period.

The £5,000 combined sale proceeds are neither a £5,000 taxable gain nor the £1,300 gain of one UK tax year. The provider could also report an August own-wallet transfer valued at £1,000 under a transfer category. Once ownership is documented, that movement does not add £1,000 to either gain. Keep a reconciliation with event date, reporting category, proceeds, matching cost, gain and UK tax year; do not combine distinct CARF categories into a disposal total.

Registration and first user notifications are due by 31 January 2027 under HMRC's provider guidance. The 2026 Transformation Roadmap update describes exchange with participating jurisdictions by 30 September 2027 as planned activity. Those provider dates do not move the taxpayer's own filing or payment deadline.

Offshore exchanges, DeFi and self-custody

“Offshore” does not mean invisible. If an overseas provider reports under CARF in a partner jurisdiction, UK-resident information can reach HMRC through automatic exchange. Conversely, a platform that is outside CARF does not remove the taxpayer's obligation to report taxable income and gains.

Direct self-custody and decentralised protocols can create gaps in provider data. A withdrawal from an exchange might be only an own-wallet transfer, while a later on-chain swap, liquidity-pool deposit or disposal may occur outside that exchange's view. Wallet addresses, transaction hashes and protocol records should therefore be reconciled with the exchange exports rather than treated as separate portfolios.

Practical preparation checklist for UK users

1. Give every provider accurate tax-residence and identification details.
2. Export complete transaction histories before an account closes or an exchange limits access.
3. Keep API and CSV data, statements, trade confirmations and wallet addresses.
4. Link deposits and withdrawals between accounts you own so they are not mistaken for disposals.
5. Reconstruct historic Section 104 pools before calculating 2026 disposals.
6. Separate capital, income, derivative and informational events.
7. Record GBP values and the valuation source at the transaction time.
8. Compare any provider CARF notification with your records, but do not treat it as a tax computation.
9. Correct known omissions through the proper HMRC route rather than waiting for a data match.

CoinTaxReporting can consolidate imported exchange and wallet records, preserve source references and apply the configured UK matching logic. It cannot decide uncertain beneficial ownership, residence, business status or legal character without reliable facts. Those cases require documented review.

Official UK sources

• HMRC: CARF guidance collection
• HMRC: collecting user and transaction data
• HMRC: reporting user and transaction data
• UK Statutory Instrument 2025/744
• OECD Crypto-Asset Reporting Framework

Frequently asked questions

Disclaimer: This article is for general informational purposes only and does not constitute tax advice. For individual tax advice, consult a licensed tax professional.