CBAM's core purpose is to make sure the emissions figures reported by non-EU producers reflect reality. A company's own emissions calculation isn't accepted on its own — it needs to be verified by an independent, accredited body.

Verification is especially critical for businesses that want to use actual values instead of default values, because the EU only accepts actual values once they've gone through a proper verification process.

CBAM verification can't be carried out by just any audit firm — it has to be done by a body accredited to the EN ISO/IEC 14065 standard, authorized specifically for greenhouse gas verification. This standard is designed to guarantee the verifier's independence, competence, and methodological consistency.

You'll need to choose a body in your country of production that holds EN ISO/IEC 14065 accreditation with greenhouse gas verification in scope. Choosing a verifier is a step you should take early — it can take time, and with a limited pool of accredited verifiers, booking capacity gets tight during peak reporting periods.

Under Commission Implementing Regulation (EU) 2025/2546, when a facility goes through verification for the first time, the verifier is required to visit the site in person. During the visit, the verifier examines production processes, measurement instruments, data collection systems, and documentation on the ground.

This isn't a formality — it's the stage where the verifier actually assesses whether the reported emissions data is consistent with real production conditions. Being unprepared for the site visit can extend the verification process or lead to a negative opinion.

In the years following the first verification, the mandatory physical site visit can be relaxed for facilities that meet certain conditions. If no significant non-conformity was found in the prior year's verification and the facility's data collection and monitoring system hasn't changed, the verifier may decide a remote review is sufficient in subsequent years.

That said, this isn't an automatic entitlement — the decision rests with the verifier's own risk assessment. If something material changes at the facility (a new production line, a different energy source, a change to the data system), a physical visit may be required again.

One of the key concepts in verification is the materiality threshold. Put simply: the error or uncertainty in your total reported emissions data is expected to stay below a level the verifier considers "material" — under Commission Implementing Regulation (EU) 2025/2546, this is generally understood to be around 5%.

If a deviation above this threshold is found, the verifier cannot issue a positive opinion, and the company needs to revisit its data collection or calculation methodology. That's why it's worth building your internal controls, well before verification, to keep data quality under this threshold from the start.

Verification isn't something to leave for the last week of your reporting calendar. Accredited verifiers have limited capacity, and booking gets harder during busy reporting periods — so it's worth starting your verifier selection and initial contact months ahead of your reporting deadline.

Pulling together the documentation a verifier will ask for (your monitoring plan, production data, energy invoices, supplier data) ahead of time directly affects how efficient the site visit is. Scattered or incomplete documentation is one of the most common reasons verification drags on.