Verification under CBAM – Key learnings and guidance for effective preparation (Part 1)

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Using actual CBAM data can substantially reduce CBAM‑related costs for importers. However, essential data points — such as direct specific embedded emissions or specific embedded free allocation — must be available in verified form to be eligible for use in a CBAM declaration.

In this series we cover the key processes and requirements for verification under CBAM along with our experiences in preparing CBAM declarants, suppliers and non-EU producers. This first part focuses on the commercial importance of verified data as well as the accreditation and verification processes.

Commercial value: Verified CBAM data vs. defaults

From 2026 onward, all CBAM-covered imports are subject to payment obligations. Costs however remain uncertain, not only because CBAM certificate prices for remaining quarters in 2026 will only be finally known ex-post, but because many importers lack clarity on availability and plausibility of actual CBAM emissions data from suppliers.

The key risk: If suppliers cannot provide verified CBAM emissions data by 30 September 2027, importers must report using default values, which are typically significantly higher. This may dramatically increase reported emissions and lead to major cost increases — potentially adding hundreds of euros per tonne — making imports economically unviable (see our article here). Figure 1 provides an overview of CBAM costs for imports of tubes and pipes from different countries in line with the default emissions values.

Figure 1: CBAM cost per tonne of tubes and pipes CN 7306 6199, based on carboneer model CBAMCC. Modelling assumptions: Import during Q1 2026, CBAM certificate price 75 €, default values, no CO2 prices paid in supply chain (source: carboneer).

Verified CBAM data therefore offers major commercial value, particularly for imports from countries facing punitive default values. Access to verified data can potentially reduce CBAM costs down to zero, safeguarding the competitiveness of both non‑EU suppliers and importers.

A key challenge arises from the split responsibilities: Emissions occur and data is generated at the supplier level, while the financial obligation to purchase CBAM certificates lies with the importer. This raises important questions about cost allocation — for example, whether cost increases should be borne by the supplier or the declarant, especially where suppliers already provide non‑verified actual data that allow for cost estimates. Possible approaches include:

• Supplier‑led hedging strategies allowing to offer products including CBAM costs

• Supplier contracts with defined markups or rebates depending on availability and final verified data

However, the availability of actual CBAM data in verified form is constrained by strict and complex calculation rules and verification requirements as laid out in the CBAM regulation and relevant implementing and delegated acts. During our work with importers and non-EU producers of CBAM goods we are confronted with recurring questions and misunderstandings regarding CBAM data calculations and verification. This series aims to clarify some of those topics and shed light on the relevant processes.

Potential bottleneck: Accreditation for CBAM verification

Verification bodies may only provide verification under CBAM if accredited by a National Accreditation Body (NAB) of an EU member state. As of today, no verification body has been officially accredited. NABs are expected to open CBAM accreditation schemes until May 2026 (the DAkkS as the German NAB already opened the application process) , with a tentative timeline for the first accreditations issued by late 2026. Accredited verification bodies will gain access to the CBAM Registry from September 2026 Accreditation as detailed in Delegated Regulation (EU) 2025/2551 is thus often a multi-month process designed to ensure verifiers’ ability and expertise of the specific rules on CBAM data monitoring and calculation (e.g. embedded emissions and embedded free allocations).

Several internationally operating verification bodies are already accredited under the European Emission Trading System (EU ETS) and will likely be the first official verifiers accredited for the CBAM scope as well. Verification bodies that seek accreditation under CBAM do not have to be EU-based but can also be located in third countries. To date, only 6 out of 21 NABs have confirmed that they will open their accreditation processes to applicants based in third countries (compare overview in Table 1).

Table 1: List of National Accreditation Bodies for CBAM verifiers in the EU

In our work, we frequently encounter “certification” or “verification” statements on CBAM data by third parties which at closer scrutiny do not hold up to the CBAM data calculation rules or conform to the CBAM verification standards. Four main bottlenecks may impede importers from using actual verified data in their CBAM declaration due 30 September 2027:

• Limited availability of accredited verification bodies and auditors

• Short verification period (Jan-Sep 2027)

• Verification requirements throughout the value chain

• Moderate level of producer preparedness

Timely preparation for verification by non-EU producers of CBAM goods already during 2026 is crucial to mitigate these risks, increase confidence in CBAM data and thus reduce prospective costs for CBAM declarants.

A complex and lengthy process: How CBAM verification works

CBAM data such as embedded emissions or embedded free allocation must be verified for each monitoring period, i.e. every calendar year, before an importer may use it in their annual CBAM declaration (see Figure 2). Verification must be performed by accredited CBAM verifiers in line with the principles in Implementing Regulation (EU) 2025/2546, using a risk‑based approach similar to the EU ETS.

Figure 2: The annual verification process (source: carboneer)

A key feature of the process are mandatory site visits as part of the verification activities: For the first year of the definitive phase in 2026, a physical on‑site visit to each installation producing CBAM goods is mandatory. From 2027 onwards, verifiers may, under defined low‑risk conditions and where no significant changes have occurred, replace a physical visit with a virtual visit or waive it entirely, but a physical site visit must still take place at least once every two years.

In practice, the verification process might take three months for well‑prepared operators but can take considerably longer in case the operator’s preparation is insufficient. The process follows several structured stages (see Figure 3): initial risk analysis and kick‑off, detailed verification planning and document request, audit and site visit with data testing and interviews, followed by processing, clarification of findings and adjustments, internal quality assurance on the verifier side, and finally issuance of the verification statement and standardised verification report in the CBAM Registry.

Figure 3: Indicative timeline and details of a CBAM verification process (source: carboneer)

As accredited verifiers are expected to be officially announced only in late 2026, non-EU producers currently should use the time to prepare for the verification process — or even conduct pre-verification activities — during 2026.

In the second part of this series, we will provide practical guidance on how producers can prepare efficiently for CBAM verification.

This article is also published on carboneer. illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability & Energy writers, their opinions do not necessarily represent those of illuminem.

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