CBAM Verification Process: What Does a Verifier Check?

Who can perform CBAM verification?

CBAM verification must be performed by a verifier accredited for CBAM activities under the applicable rules. Verifiers are legal persons (companies), and accreditation is granted by a National Accreditation Body (NAB) against EN ISO/IEC 17029 and EN ISO 14065 together with the CBAM-specific rules (Delegated Regulation (EU) 2025/2551). Verification companies established outside the EU may apply to a National Accreditation Body offering CBAM accreditation services. Accreditation and access to the CBAM Registry are separate steps: verifiers register in the Registry within two months of their accreditation.

As currently indicated by the European Commission: the CBAM Registry has been open to accredited verifiers since 1 September 2026, and accredited CBAM verifiers can issue the first verification reports from January 2027. Those reports concern emissions data relevant to the definitive period that began in 2026.

Verification is at installation level

CBAM verification applies at the level of the INSTALLATION where the CBAM goods are produced: installation → production processes and products → embedded-emissions calculation → verification report. For stationary installations the "site" is always the physical location of the installation; the verifier assesses the installation boundaries, the processes and the completeness of source streams on that basis.

That is why CBAM verification is not "getting a product carbon footprint verified": a stand-alone product GWP number, without installation and methodology evidence, does not give a verifier the traceability needed for reasonable assurance. The installation data, calculation files and records behind the number are the real subject of the examination.

What does the verifier actually look at?

The groups below are compiled from the current CBAM methodology and verification guidance. Not every item applies identically to every installation or sector; the scope depends on the nature of the installation, its sector and the method used.

Reasonable assurance and materiality

CBAM verification is performed to a REASONABLE ASSURANCE level: the verifier assesses whether the emissions report is free from material misstatements and material non-conformities. Reasonable assurance is not absolute assurance — reducing verification risk to zero is not the aim, and verification does not guarantee that every cell is error-free; it aims to provide reasonable assurance that material errors and methodology non-conformities remain below the level that would compromise the verification opinion.

The materiality level is defined in legislation (Implementing Regulation (EU) 2025/2546, Art. 5): for every good identified by its CN code, 5% of the specific embedded emissions (SEE), and 5% of the specific embedded free allocation (SEFA). For all other parameters the verifier applies expert judgement based on the size and nature of misstatements — and a misstatement below the threshold can still be material by its nature; the threshold is not a mechanical free pass.

Site visits

The rule: the verifier is required to carry out site visits to the installation at one or more appropriate times during the verification process (Regulation (EU) 2023/956 Annex VI point 1(c) and Delegated Regulation (EU) 2025/2551 Annex II, 2.13). The visit is used to assess the installation boundaries, the production processes, the completeness of source streams, and the operation of measuring devices and monitoring systems on site.

Exceptions are defined in Implementing Regulation (EU) 2025/2546: under certain conditions a "virtual site visit" is allowed, and under certain conditions — in particular for very small and simple installations — the site visit may be waived. In both cases the verifier must still be able to obtain reasonable assurance, and the decision must be recorded in the internal verification documentation. So neither "every verification always requires a site visit" nor "site visits are optional" is correct.

Remote verification does not automatically mean that an installation visit is unnecessary.

What happens during the verification process?

The flow described in the guidance — the depth of each step varies with the installation and its risks:

1. 1The operator prepares the emissions calculation and the evidence set
2. 2Pre-contract stage with the verifier and planning of the verification
3. 3Strategic analysis and risk analysis
4. 4Examination of data flows, methodology and controls (process analysis)
5. 5Installation visit where required (per the rule above)
6. 6Findings; corrections and treatment of data gaps where necessary
7. 7Internal verification documentation and independent review
8. 8Final verification conclusion and the verification report

What is in the verification report?

The minimum content of the report is defined in the Annex to Implementing Regulation (EU) 2025/2546. At a high level: operator and installation identification, the reporting period, verifier identification, information on the goods and emissions, findings, and — at the core of the report — the verification statement. The report is issued in English through the CBAM Registry; if the operator is not registered, the report is exported from the Registry and transmitted separately.

What should the manufacturer prepare before contacting a verifier?

A practical preparation checklist — the items that most shorten the verifier’s work (and your timeline):

• ☐ Installation and operator details
• ☐ Reporting period
• ☐ CBAM product / CN code mapping
• ☐ Production route
• ☐ Production quantities
• ☐ Relevant emission and activity data
• ☐ Relevant precursor information
• ☐ Allocation methodology
• ☐ Calculation workbook / model
• ☐ Monitoring methodology and documentation
• ☐ Source evidence (meters, invoices, production records)
• ☐ Internal reconciliation and consistency checks

Calculation ≠ Documentation ≠ Verification

Most installations can produce the first column; verification is decided in the second and third.

Common pre-verification problems

These are not official "failure criteria"; they are issues that, in practice, may make verification difficult:

• CN/product scope inconsistent with production records
• Production quantities and energy/fuel data covering different periods
• Undocumented allocation approach
• Missing precursor information
• Unexplained manual spreadsheet adjustments
• Incomplete audit trail; values that cannot be traced back to source evidence
• A calculation methodology that does not match the applicable CBAM requirements
• An EPD/PCF result used directly without mapping to the CBAM methodology

Frequently asked

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