Live in the UK: CARF requires crypto firms to report by May 2027
The Crypto-Asset Reporting Framework (CARF) has been up and running in the UK since 1 January 2026, data collection is already underway in theory, and the first filings by UK Reporting Crypto-Asset Service Providers (RCASPs) are due by 31 May 2027.
By Paul Foster Millen (2 October 2026)
The dates that matter
1 January 2026 — activation date for due diligence and data collection obligations for UK RCASPs.
31 January 2027 — deadline to register with HMRC's online service and to notify users that their details will be reported via the mandatory one-time customer notification requirement.
1 January to 31 May 2027 — window to file the first report, covering calendar year 2026. Annually by 31 May thereafter.
Who is reportable
Collect on everyone; report on a subset. Due diligence, backed by a valid self-certification, runs across the whole user base. The reporting population is any party tax resident in the UK or in a CARF Jurisdiction. NB: There is local domestic reporting requirement for UK CARF, which is absent from UK CRS.
For individuals (including Controlling Persons of certain entity users): name, address, jurisdiction(s) of tax residence, TIN(s) and date of birth. For entities: name, address, jurisdiction(s) of tax residence and TIN(s). In addition, for Controlling Persons: the role by virtue of which they are a Controlling Person. The RCASP reports its own identifying details too (Template forms, training, guidance packets and more are available on CARFtools).
How reports are segregated
This is the part that drives system design. Transactions are reported on an aggregate basis per user, split by each relevant cryptoasset and by transaction type.
Cryptoassets are identified by full name, aligned to the digital token identifier where one exists. Fungible units of the same asset aggregate together; non-fungible assets are each treated as a separate type (i.e. a portfolio of NFTs does not fit onto one line).
The transaction categories are:
Exchanges against fiat currencies — acquisitions and disposals, reported as gross amounts paid or received net of transaction fees, in a single fiat currency converted consistently at transaction time.
Crypto-to-crypto exchanges — between one or more forms of relevant cryptoasset.
Transfers – covering reportable retail payment transactions (goods or services above USD 50,000), other transfers to and from a reportable party, and transfers to external wallet addresses.
The CARF XML reporting schema presents further transfer types — airdrops, staking, mining, collateral, crypto loans and others — which must be used to the extent the RCASP has knowledge of the transfer type.
The portal remains unspecified, but some technical details are available
There is no live HMRC CARF portal yet. Per HMRC's most recent guidance update, the portal is described only as "the online service" and is flagged as not yet live, with guidance to follow once it launches. We may expect to access the future portal via Government Gateway credentials, as with other UK automatic exchange of tax information regimes.
Two practical points are already fixed. Reports must be submitted as XML built to the OECD CARF schema, with a file size ceiling of 250MB. And while an RCASP can appoint a third party to file on its behalf, accuracy and completeness remain the RCASP's responsibility.
The cost of getting it wrong
Penalties run to £300 per user for failure to report, late filing, or reports that are inaccurate, incomplete or unverified. Seems low, but multiplied across a retail user base, that can scale up significantly.
Sources: HMRC guidance on reporting cryptoasset data, and the CARF chapter of HMRC's International Exchange of Information Manual (IEIM8000030 onwards).
Disclaimer: This article is intended for general informational purposes only and does not constitute legal or regulatory advice. Parties should seek qualified legal counsel regarding their specific obligations under the applicable CARF/DAC8 regulations.