ARKK Blog

CARF Explained: UK Crypto Reporting Rules

Written by ARKK | 31/03/2026

CARF Explained: UK Crypto Reporting Rules

For years, crypto-assets existed in a regulatory grey zone, traded freely and largely invisible to tax authorities. While the Common Reporting Standard (CRS) transformed global tax transparency for traditional financial accounts, crypto remained outside its scope.

That gap is now being closed with the OECD’s Crypto-Asset Reporting Framework, known as CARF.

Finalised in 2023, CARF brings crypto into the automatic exchange of information regime. It gives tax authorities access to detailed, standardised data on crypto transactions. With data collection starting on 1 January 2026 and first reporting due in May 2027, firms need to start preparing now.

What is CARF and why was it introduced?

The Crypto-Asset Reporting Framework was introduced by the OECD to address a growing problem. Cryptoassets allow users to move value outside traditional financial systems, making it harder for tax authorities to track activity and enforce compliance.

CARF aims to:

  • Improve global tax transparency
  • Close reporting gaps left by CRS
  • Enable cross-border sharing of crypto transaction data
  • Reduce tax evasion and avoidance

In the UK, CARF goes further than the global baseline. HMRC will receive data on both overseas activity and UK-resident users of UK-based platforms. This gives a much more complete picture of taxpayer activity.

Who needs to comply with CARF?

CARF applies to Reporting Cryptoasset Service Providers, or RCASPs. This includes:

  • Crypto exchanges
  • Wallet providers
  • Brokers and intermediaries

If your business facilitates crypto transactions in any way, there is a strong chance you fall within scope.

It is also important to note that even if your organisation is not an RCASP, you may still need to provide data to another institution to support their reporting obligations.

What are the CARF reporting requirements?

CARF introduces a new level of reporting detail. Unlike CRS, which focuses on accounts, CARF focuses on transactions.

RCASPs must:

  • Carry out due diligence on users
  • Collect self-certifications and tax residency details
  • Identify reportable users across jurisdictions
  • Report crypto transactions annually to tax authorities

Each report must include:

  • The type of cryptoasset, including stablecoins, NFTs, and tokenised assets
  • The value of the transaction
  • The nature of the transaction, such as transfers or exchanges

This transaction-level reporting significantly increases data volumes and complexity.

UK CARF timeline and key deadlines

The UK has now confirmed its implementation timeline, and the deadlines are approaching quickly.

Key dates to know:

  • Start of data collection: 1 January 2026
  • Reporting period: 1 January 2026 to 31 December 2026
  • HMRC registration deadline: 31 January 2027
  • First CARF reporting deadline: 31 May 2027

Reports must be submitted in XML format, which means firms need structured, high-quality data from the outset.

DAC8: what UK firms with EU clients should know

If your business has EU clients, DAC8 is also relevant.

DAC8 is the EU’s implementation of CARF and introduces additional requirements:

  • It applies regardless of where the provider is based
  • Penalties for non-compliance can be significant

This creates additional complexity for firms operating across multiple jurisdictions. 

Why CARF matters now

CARF represents a major shift in how crypto is regulated and reported. It brings cryptoassets into the same transparency framework as traditional finance, but with greater complexity due to transaction-level reporting.

Firms that act early will be better placed to manage risk, avoid disruption, and maintain trust with regulators and clients.

Those that delay may face significant operational challenges as deadlines approach.

At ARKK, we support organisations that fall within scope of CARF reporting by helping them manage the complexities of data collection, validation, and regulatory reporting. As CARF and CRS 2.0 reshape global reporting, having the right approach in place will make all the difference.