CBAM Verification: How Emissions Data Is Verified

UK CBAM does not require mandatory verification of all emissions data. Instead, it incentivises verification by allowing verified emissions data to be used directly in your CBAM calculation, while unverified data attracts a risk weighting that increases your effective emissions figure.

Verification is performed by an independent, accredited third party — a verifier. The verifier reviews the producer's emissions data against recognised standards such as ISO 14064, the GHG Protocol, or sector-specific methodologies. The verifier issues a verification report confirming that the data is accurate and complete within a stated materiality threshold.

The verification report is issued to the producer, not to the importer. This is a critical point: the importer cannot commission the verification directly. You must request a copy of the verification report from your supplier as part of your data collection process.

Verifiers must be accredited by a recognised national accreditation body. In the UK, the United Kingdom Accreditation Service (UKAS) accredits verifiers under ISO 14065 (greenhouse gas validation and verification bodies). Other national accreditation bodies such as DAkkS (Germany), COFRAC (France), or ANSI (USA) are also recognised where their accreditation follows equivalent standards.

Verifiers must be independent of the producer and impartial in their assessment. A verifier cannot be the producer itself, a related party, or an organisation with a financial interest in the outcome of the verification. The verifier must have competence in the specific industrial sector — verifying steel emissions requires different expertise than verifying fertiliser emissions.

As UK CBAM matures, HMRC may publish a list of recognised verifiers or accreditation bodies. For now, the general principle is that verification by any ISO 14065-accredited body is acceptable, provided the verifier has sector-specific competence.

A verification report for CBAM purposes typically includes: the name and address of the verified producer, the reporting period covered, the product types and quantities covered, total Scope 1 and Scope 2 emissions separately stated, emissions intensity per tonne of product, the methodology used for emissions calculation, the verification standard applied, the materiality threshold used, the verifier's opinion (unqualified, qualified, or adverse), and the verifier's accreditation details and signature.

The report must be current for the production period you are reporting on. A verification report from 2025 cannot support a 2027 CBAM return unless it specifically covers the 2027 production period. Some producers obtain annual verification; others obtain verification every two or three years. You need verification for each period you are reporting.

If the verification report is qualified (i.e., the verifier identifies issues with the data), you should understand the nature of the qualification and how it affects the emissions figures. A qualification about data completeness may mean the verified figure is still an underestimate, and you may need to supplement it with default values for the unverified portion.