CARF, DAC8, and HMRC's Crypto Reporting, What's the Difference?

For most crypto-asset service providers (CASPs) the question is no longer whether they have to report customer information to tax authorities, it is which set of rules they have to report under, in what format, and on what timeline. Three regimes dominate the conversation: the OECD's Crypto-Asset Reporting Framework (CARF), the EU's DAC8 directive, and the United Kingdom's domestic HMRC crypto-asset reporting rules. They look similar from a distance. They are not the same up close.

Overview

All three regimes implement the same underlying policy idea: automatic exchange of information about crypto-asset transactions between tax authorities, modelled on the Common Reporting Standard (CRS) that has governed traditional financial accounts since 2014. They diverge on three dimensions that matter operationally:

Scope: which providers, which users, which transactions are in.
Legal vehicle: voluntary international framework, binding EU directive, or domestic statute.
Schema and deadlines: the file format, channel, and date a CASP must actually submit something.

The OECD CARF

CARF is the global baseline. It was published by the OECD in 2022 as a model framework for the automatic exchange of information about crypto-asset transactions. CARF defines the reportable population (Reportable Persons, Reportable Crypto-Assets), the due diligence procedures (self-certifications, residence determination), and the data model (the CARFxml XML schema, currently at v1.5).

Critically, CARF is voluntary at the framework level. Each jurisdiction adopts CARF into domestic law on its own timetable. As of early 2026, 76+ jurisdictions have publicly committed to CARF exchanges starting in 2027 or 2028. A CASP only has to report under CARF if the jurisdiction it is tax resident in has actually transposed CARF into local law.

Plain English

CARF is the rulebook. It does not bite a CASP directly, only the domestic legislation that adopts CARF does.

The EU DAC8

DAC8 is the European Union's transposition of CARF into binding directive form (Council Directive 2023/2226, adopted October 2023). Every EU member state must transpose DAC8 into national law by 31 December 2025. The first reporting period is CY2026, with the first filings due in 2027.

Two things make DAC8 different from a plain CARF adoption:

Single-MS registration model. A non-EU CASP with any EU user nexus must register in one EU member state and report through that state's tax authority for its entire EU population. A Singapore-licensed exchange with Austrian and French users can pick (say) Ireland and report there.
Extraterritorial reach. DAC8's "nexus" test (Article 8ac) catches any CASP that provides services to EU residents, not only CASPs established in the EU.

The UK's HMRC regime

The United Kingdom left the EU before DAC8 was adopted, so it has built its own equivalent. HMRC's crypto-asset reporting rules are aligned with CARF on data content but operationally distinct: a separate registration, a UK-specific submission channel, and a UK deadline (first reporting period CY2026, first submission due 31 May 2027).

UK CASPs that also have EU users face both regimes in parallel: HMRC for the UK population, DAC8 (via a single EU member state) for the EU population. The data overlaps substantially, but the filings are separate.

Side-by-side comparison

	OECD CARF	EU DAC8	UK HMRC
Legal vehicle	Model framework	Binding EU directive	Domestic UK statute
Geographic scope	76+ adopting jurisdictions	EU-27 (extraterritorial via nexus)	United Kingdom
Schema	CARFxml v1.5 (OECD)	CARFxml v1.5 + EU envelope	UK-specific (CARF-aligned)
First reporting period	CY2026 (early adopters)	CY2026	CY2026
First filing deadline	Varies (typ. 30 Sep 2027)	30 Sep 2027 (SE 1 Apr 2027)	31 May 2027
Retention	5 to 10 yrs (varies)	10 yrs (Art. 8a(6))	6 yrs (HMRC standard)

Which rules apply to you?

The rule of thumb is to identify where users live, not where the CASP is licensed:

You only serve UK users. HMRC regime only. Register with HMRC. File by 31 May after the reporting year.
You only serve EU users. DAC8. Pick one EU member state for registration (if not already established in one). File by 30 September after the reporting year.
You serve both. Both regimes apply in parallel. The data content overlaps but the submissions are separate.
You serve users in CARF-adopting jurisdictions outside the EU/UK (e.g. New Zealand, Singapore once adopted, Switzerland). Domestic CARF rules of those jurisdictions apply.

Determining nexus is fact-specific. Marketing, language localisation, accepting local bank rails, and physical presence all factor in. When in doubt, treat a jurisdiction as in-scope and engage local counsel.

Common misconception

DAC8 does not replace CARF or HMRC's rules. It is the EU's way of implementing CARF, with extra teeth (extraterritorial reach and the single-MS registration). UK CASPs do not "get out" of DAC8 by being UK CASPs, they get into it via EU nexus.