Crypto tax in the UK —
what CARF means for you

Since 1 January 2026, UK crypto exchanges and wallet providers have been collecting detailed personal and transaction data on every user, ready to report it directly to HMRC. This is the UK's implementation of the OECD's Crypto-Asset Reporting Framework (CARF) — an international system designed to give tax authorities the same automatic visibility into crypto holdings that they have long had over bank accounts. If you buy, sell, or earn cryptocurrency in any form, this materially changes the odds of an unreported gain going unnoticed.

This post explains what CARF actually requires, the key dates, what counts as a taxable event, and what to do if your past returns may not fully reflect your crypto activity.

What is CARF and why does it exist?

The Crypto-Asset Reporting Framework is a global reporting standard developed by the OECD, with 51 jurisdictions — including the UK — committed to implementing it. It works in a similar way to the Common Reporting Standard (CRS), which has applied to traditional bank accounts and investments for years: financial institutions collect account holder information and report it to their local tax authority, which then automatically shares it with tax authorities in other participating countries.

Before CARF, HMRC could request crypto transaction data from exchanges, but only on a case-by-case basis. Crypto has effectively been the largest remaining gap in HMRC's automatic information network. CARF closes that gap by making structured, annual reporting mandatory rather than something HMRC has to specifically request.

The key dates

Crucially, this reporting obligation does not change your existing tax obligations — you are still required to report crypto gains and income through Self Assessment in the normal way, on the normal deadlines. What changes is that HMRC will, from 2027, have an independent data feed to check your return against.

What crypto platforms will report

• Exchanges between cryptoassets and traditional currency (buying and selling)
• Exchanges between one cryptoasset and another (token-to-token trades)
• Transfers of cryptoassets, including wallet-to-wallet movements
• Crypto debit card payments and stablecoin transactions
• Your identity details, tax residence, and tax identification number

This is a significantly wider scope than many crypto holders expect — it is not limited to cashing out into pounds sterling. A token-to-token swap, for example, is a disposal for UK Capital Gains Tax purposes, even though no traditional currency changes hands.

What actually counts as taxable

CARF is a reporting mechanism, not a new tax. The underlying UK tax rules on cryptoassets are unchanged — what matters is understanding which of your activities actually trigger a tax charge.

Activity	Tax treatment
Selling crypto for GBP	Capital Gains Tax on the gain
Swapping one token for another	Capital Gains Tax — treated as a disposal of the token given up
Spending crypto on goods or services	Capital Gains Tax on any gain since acquisition
Gifting crypto (other than to a spouse or civil partner)	Capital Gains Tax, based on market value at the time of the gift
Transferring between your own wallets	Not a disposal — no CGT event, provided you retain beneficial ownership throughout
Mining, staking, or lending rewards	Generally Income Tax (and possibly NI) when received, based on market value at receipt
Later disposal of staked/mined tokens	A separate Capital Gains Tax event on top of the income tax already paid on receipt

Since the 2024/25 tax year, HMRC's Self Assessment form includes a dedicated section within the Capital Gains pages specifically for cryptoasset gains and losses — a clear signal of how seriously HMRC now treats this area. There is currently no equivalent dedicated income box for crypto-derived income such as staking or mining rewards, meaning these need to be correctly categorised elsewhere on the return.

If your records don't match what platforms will report

If you think you may have under-reported crypto gains or income in previous tax years, the practical options are:

• Correct through Self Assessment if you are still within the amendment window for a previously filed return
• Use HMRC's Cryptoasset Disclosure Service for a formal voluntary disclosure covering earlier years, which is generally treated more favourably than waiting for HMRC to identify a discrepancy itself
• Reconstruct your records carefully where you cannot access complete exchange history — keeping a documented audit trail of your assumptions and source data is far more defensible than presenting unexplained figures

Being proactive matters here specifically because of what CARF changes: previously, HMRC had to request information before it could compare it against your return. From 2027, it receives a structured annual feed automatically. A mismatch between what platforms report and what you declared is far more likely to be flagged than it has been in the past.

Practical record-keeping

• Keep a record of every acquisition and disposal — date, quantity, sterling value at the time, and the platform or wallet used
• Where you use multiple exchanges or wallets, keep records that let you connect movements between them, so a transfer between your own wallets isn't mistaken for a disposal
• Note the basis of any valuation used where a token's sterling value at the time of a transaction isn't straightforward
• Consider specialist crypto tax software (several UK-focused platforms exist) to consolidate transaction histories across exchanges into a usable tax calculation, particularly if you trade across multiple platforms

This article is for general information purposes and does not constitute tax advice. Cryptoasset tax treatment depends on the specific facts of each transaction and continues to evolve. Always speak to a qualified accountant before filing a return involving crypto activity.