Emissions data need sufficiently reliable evidence before they can be used in CBAM declarations.
For actual emissions data, verification is an independent assessment of the calculation methodology, figures and supporting evidence. Businesses need to define the scope of work, select an appropriately CBAM-accredited verifier and prepare records early enough to deliver them to EU customers on time.
Verification does not certify that a business has met every CBAM obligation. The verification conclusion relates to the report, production installation and data period examined.
What is CBAM verification?
CBAM verification is an independent assessment of a production installation's emissions report against CBAM requirements. The verifier examines the calculation methodology, data and supporting records, then states its conclusion in a verification report.
In some documents, the term verification is translated into Vietnamese using expressions meaning “checking and confirmation” or “review”. This article consistently uses “verification”.
CBAM requires a reasonable level of assurance: the verifier must obtain sufficient evidence to conclude that the report is free from material misstatements—errors that could significantly affect the reported results. This is a high level of assurance, but not absolute assurance, and does not necessarily require checking every data item. See the EC guidance on verification.
When do data need to be verified?
For goods other than electricity that are subject to CBAM obligations, distinguish three cases:
Verification is required before use in a declaration
When the declarant uses actual emissions data, they must be verified by an appropriately CBAM-accredited verifier. A factory's own calculations and signed confirmation do not replace independent verification.
EC-published values do not need separate verification
The declarant must still select the correct default values and provide the goods information required by the rules. Using default values does not exempt it from other CBAM obligations.
The factory's report still needs verification
For example, a factory may use actual production process data and default emissions values for certain input materials and semi-finished goods to be included under CBAM. Its report must still be verified, including checks on the selection and use of the relevant default values.
Basis: Articles 7–8 of the amended CBAM Regulation and guidance for non-EU installation operators. Electricity has its own methodology and conditions for using actual data.
Clarify the purpose of the customer's request. Data checks for supplier assessment or quotations may differ in scope from verification for CBAM declarations. Businesses should agree on the purpose, assessment criteria and records to be delivered.
Who may perform CBAM verification?
The verifier must hold CBAM accreditation with an appropriate scope, granted by an EU national accreditation body, and be registered in the CBAM Registry. Its accreditation scope must cover the activity group to be verified at the production installation. See the EC information and EA's explanation of accreditation.
Before signing a contract, clarify the following
- Responsible entity: The legal entities signing the contract, performing verification and issuing the report; clarify each entity's role if several parties are involved.
- Accreditation scope and validity: Check the accreditation certificate, scope annex and current status. A claim of “competence in greenhouse gas verification” alone is insufficient to demonstrate compliance with CBAM requirements.
- Service scope: Production installation, products, reporting period, factory visit schedule, deliverables and conditions for additional charges.
Independence must be maintained. The verifier, or a part of the same legal entity, must not provide consultancy to the installation being verified that creates a conflict of interest, such as preparing its monitoring plan or emissions report. See Regulation (EU) 2025/2551.
What does the verifier examine?
The verifier examines the calculation methodology, data and supporting evidence to assess the report's reliability. The main areas include:
Scope and methodology
Production installation, products, reporting period, monitoring plan, and the processes and emission sources included in the calculations.
Data and supporting records
Output, fuel and material consumption, measurement results and the basis for selecting calculation factors; the ability to reconcile results with source data and records.
Input data and allocation
Emissions information for input materials and semi-finished goods to be included under CBAM; how data are aggregated and allocated to each production process.
Calculation results and adjustments
Embedded emissions results and, where relevant, information supporting the EU free allocation adjustment; discrepancies identified and corrective action taken.
The specific checks are determined by the EC guidance on verification and the requirements applicable to the installation.
The verification process usually has four steps
- 1Agree the scope and plan the work
- 2Review records and conduct the site visit
- 3Clarify and correct discrepancies
- 4Independently review the verification results and issue the report
Is a physical factory visit required?
In principle, the first verification requires a physical site visit, except in special circumstances provided for in the rules. In subsequent periods, remote visits or site-visit waivers are permitted only when all applicable conditions are met. A site-visit waiver does not waive verification of the report. See Regulation (EU) 2025/2546.
How should you prepare records and schedule verification?
Businesses should prepare a systematic set of records so that figures can be checked, reconciled and traced to their sources during verification, including:
- Installation records: factory information, product lists and CN codes, production process diagrams, the monitoring plan and the responsible person's details.
- Data records: calculation spreadsheets and emissions reports; output data; evidence of raw material, fuel and energy consumption; measuring equipment records; data on input materials and semi-finished goods to be included under CBAM; and related documents.
- Control records: internal check and reconciliation results; changes in calculation methodology; document version history; explanations and records of error correction.
Note: This is a suggested way to organise records. The detailed list should be agreed with the verifier to reflect each factory's activities and the applicable CBAM requirements. See also CBAM data: What should businesses prepare?
Collect data, check record completeness and discuss the verification schedule early. Under the EC timeline, document reviews and factory visits may begin from September 2026 with an appropriately accredited verifier.
Finalise the compilation of 2026 emissions data, provide records and address requests for additional information or explanations. Under the EC timeline, accredited verifiers may begin issuing verification reports from January 2027. This is not a mandatory deadline for every business to complete verification.
Deliver verified emissions data and the verification report by the deadline agreed with the EU customer. Allow contingency time for the partner to review the information, request additions and finalise the declaration. The first CBAM declaration deadline for authorised CBAM declarants is 30/09/2027, for goods imported into the EU in 2026. See the EC's CBAM Questions and Answers.
Allow time to supplement records and correct errors. Agree early on the data submission date, factory visit schedule, deadlines for explanations and corrective action, and the expected verification report date. Do not wait until the customer's deadline is approaching to look for a verifier.
What should businesses do after receiving the verification report?
Check the conclusion and any outstanding issues. Receiving a verification report does not automatically mean the data are eligible for use in a CBAM declaration. Uncorrected material misstatements or insufficient evidence to achieve reasonable assurance may lead to an unsatisfactory verification outcome. In that case, the relevant data cannot be used as verified actual emissions data. See the EC guidance on verification conclusions, sections 4.15–4.16.
Before delivery, check the production installation's name and identifiers, reporting period, products, CN codes and the data version verified. Discuss any errors, non-conformities or recommendations recorded in the report with the verifier and agree how to address them.
Installation A's verification report cannot confirm installation B's emissions data simply because both belong to the same business.
One production installation, multiple EU customers
A business may provide the same verification report to several EU customers buying goods produced at that installation, provided the data used match the products and reporting period verified. Each CBAM declarant must still reconcile the data with its imports and meet its own declaration obligations. See the EC information on verification at installation level.
If errors are found or data for a verified period need to be corrected: notify the verifier and all data recipients promptly so they can assess the impact and determine whether the report and any declarations need to be amended. Do not revise a spreadsheet yourself and continue sending it with the verification report for the previous data version.
The authorised CBAM declarant remains responsible for the content of the declaration, including when using a third-party verification report. See the EC's CBAM Questions and Answers, section 5.13.
Prepare data for verification
Start by correctly identifying the production installation, products and reporting period. Then review and complete the records, select a verifier with the appropriate accreditation scope, and agree the verification schedule and deadline for delivering results to EU customers.
Learn more about the service scope and records to prepare on the GIC Vietnam CBAM Embedded Emissions Verification page.
Updated as of 11 September 2026. This article focuses on the definitive period, based on Regulation (EU) 2023/956, as amended, Regulations (EU) 2025/2546 and 2025/2551, and the EC's relevant legislation and guidance.
