UK Implements Crypto Tax Reporting Rules from Jan 1, Joins 48 CARF Adopters

Key Insights:

• UK crypto exchanges must collect and report user transaction data directly to HMRC under OECD CARF rules from Jan 1.
• Exchanges must record buy and sell prices, gains and taxpayer details, while cross-border sharing of data starts in 2027.
• UK is among the first 48 CARF adopters, and 75 countries have agreed to implement the framework

United Kingdom started a new phase of crypto tax enforcement, shifting more reporting duties to crypto exchanges and other service providers. The policy targets undeclared gains and income tied to buying, selling, and transferring cryptoassets, where tax authorities have said they see persistent underreporting.

New reporting regulations took effect on January 1 in the United Kingdom and in a first wave of other jurisdictions adopting the OECD Cryptoasset Reporting Framework, also known as CARF. Under the rules, cryptoasset service providers must identify customers and capture standardized data on crypto transactions tied to UK residents and other participating countries.

The crypto news reported that the United Kingdom is among an initial group of 48 countries moving first, while a broader set of jurisdictions has committed to the framework. The OECD model aims to align crypto reporting with existing tax information sharing standards used for traditional financial accounts.

OECD monitoring documents say 75 jurisdictions have made political commitments to implement CARF, with first exchanges expected between 2027 and 2029. The United States is scheduled to start later than the early adopters under its planned timeline.

Platforms that provide crypto exchange, brokerage, or custodial services must begin gathering information that links activity to a specific person or business. HMRC guidance says providers need core identity and tax residence details, including name, date of birth, home address, country of residence, and a National Insurance number or Unique Taxpayer Reference for UK residents.

For non-UK residents, providers must capture a tax identification number and the issuing country, where available.

For each reportable transaction, the rules require data on value, the cryptoasset involved, the type of transaction, and the number of units. Providers must also run due diligence steps to verify the accuracy of the information they record before submitting annual reports.

HMRC is expected to use reported exchange data to compare declared figures against observed activity and to follow up where returns appear incomplete. Notably, HMRC expects the change to support the recovery of at least £300 million in unpaid tax over the next five years.

The UK tax system already treats many crypto disposals as taxable events, including sales or exchanges that create gains above annual allowances.

Separate compliance measures also aim to raise disclosure rates for earlier years. Tax advisers have said HMRC is promoting voluntary disclosure for past periods through a disclosure service for undeclared crypto gains, while also increasing outreach to suspected non-compliant taxpayers.

While platforms start collecting data in 2026, cross-border sharing of CARF information is scheduled to begin in 2027. UK government documentation says the United Kingdom is implementing CARF to support the first international exchanges of crypto tax data in that year. This will enable automatic sharing with partner tax authorities that also adopt the standard.

The crypto news reported that major financial centers such as Singapore, Switzerland, and the United States are expected to join the information-sharing process later in the decade.

Meanwhile, the Financial Conduct Authority continues consulting on conduct and market standards for crypto firms. It also follows UK United States coordination through a transatlantic task force announced in September 2025.

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