Prior to the entry into force of the definitive regime of the Carbon Border Adjustment Mechanism (CBAM) on 1 January 2026, several key implementing acts were adopted by the European Commission in December 2025, providing operational clarification on the functioning of the mechanism: use of default values, purchase of certificates, carbon price benchmarks in third countries, and customs declaration procedures.
1. Adoption of the “core” CBAM implementing regulations
The adopted texts specify in particular:
– The methods for calculating embedded emissions;
– The rules governing the use of actual emissions, based on emissions data from production installations, supported by monitoring plans, standardised reports and verification by an accredited verifier;
– The conditions for using default values, applicable in the absence of verified data, with parameters defined by product type and country of origin;
– The system boundaries, production processes and functional units applicable to each category of covered goods, as well as the rules for allocating emissions to imported products, including for complex products and precursors;
– The establishment of default values and sectoral benchmarks, based on a conservative approach designed to avoid any underestimation of emissions, combined with a progressive mark-up intended to incentivise operators to switch to actual emissions data;
– The rules for calculating the adjustment linked to free allowances under the EU ETS, in order to ensure a gradual economic equivalence between EU producers and importers, as free ETS allowances are phased out;
– The method for determining and publishing the price of CBAM certificates, which is directly indexed to EU ETS auctions, with prices calculated on the basis of quarterly averages in 2026, and weekly averages from 2027 onwards, more closely reflecting volatility in the European carbon market.
Taken as a whole, these regulations confirm strong methodological continuity with the EU ETS, while significantly strengthening requirements related to traceability, justification, documentation and verification of emissions data, as well as the scope for ex post controls by the competent authorities.
2. Default values: confirmed increase and an explicitly “penalising” logic
The default values, now formally adopted through implementing regulations, have been updated compared to the working versions used during the transitional phase. They are established by product type and country of origin, based on the most recent available data, and incorporate an adjustment coefficient intended to reflect the dispersion of performance across production installations.
In parallel, the ETS sectoral benchmarks, used to calculate the adjustment linked to the remaining free allowances under the EU ETS, have been revised to reflect the performance levels applicable to the relevant reference period.
Operational consequence: the combination of these parameters leads, all else being equal, to an increase in the number of CBAM certificates needed for imports, particularly where operators rely on default values rather than verified actual emissions data.
3. Introduction of a progressive “mark-up” on default values
The implementing regulations adopted in December 2025 provide that default values applicable to embedded emissions are subject to a progressive adjustment coefficient, intended to account for the potential gap between average performance and the individual performance of production installations.
This coefficient applies according to the following schedule:
– 10% for imports made in 2026;
– 20% for imports made in 2027;
– 30% for imports made from 2028 onwards.
This mechanism applies where embedded emissions are determined on the basis of default values, in the absence of duly documented and verified actual emissions data in accordance with Regulation (EU) 2023/956 and its implementing acts.
It is specified that, for products in the fertiliser sector, a specific adjustment coefficient applies, set at 1%, in line with the sector-specific rules.
4. “Provisional” benchmarks for 2026
The implementing regulations provide that the benchmarks applicable for 2026 are established, on a transitional basis, using data from the EU ETS covering the 2021–2025 period.
These benchmarks are intended to be revised from 2027 onwards, in order to align them with the next ETS cycle and the most recent available data, in accordance with the revision schedule laid down in Regulation (EU) 2023/956.
Operational consequence: for the first year of application of the definitive regime, operators benefit from stabilised reference parameters for 2026, while being aware that these parameters may be updated in the short term as part of the planned revisions.
5. CBAM certificates price: clarifications
The implementing regulations clarify the method for determining the price of CBAM certificates, which is directly indexed to the price of allowances under the EU ETS.
Accordingly:
– For 2026, the price of CBAM certificates is determined on the basis of quarterly averages, calculated from the weighted auction prices of ETS allowances;
– From 2027 onwards, the price is established on the basis of weekly averages, more closely reflecting developments in the ETS market price.
For 2026, and in line with previous announcements by the Commission, CBAM certificates may effectively be purchased in 2027, with retroactive effect.
The prices thus determined are published by the European Commission and made available to authorised CBAM declarants via the CBAM Registry, in accordance with Regulation (EU) 2023/956 and its implementing acts.
6. Customs déclarations implementation: operational clarifications in France
In December 2025, the French Customs Authority (DGDDI) published several notices to operators confirming the full integration of CBAM into TARIC as of 1 January 2026. Several practical points require particular attention:
– Obligation to hold an authorised CBAM declarant number (code Y128). When lodging the customs declaration, code Y128 and the CBAM declarant number must be included in the dataset as an accompanying document at item level, and not as a supplementary reference.
– Entering code Y128 as a supplementary reference triggers manual customs controls, thereby slowing down clearance;
– An automated consistency check (GUN–CERTEX link) between the authorisation number entered in the customs declaration and the CBAM Registry enables immediate release of the goods;
– Where the importing operator has submitted an application for authorised CBAM declarant status that has not yet been processed, code Y238 must be used;
– Any application for authorised CBAM declarant status must be submitted no later than 31 March 2026;
– Introduction of new declarative codes for goods of EU origin (code Y237), goods intended for military use (code Y135), goods exempt due to the 50 tonnes/year threshold (code Y137), goods intended to be placed under inward processing (code Y422).
7. Developments to monitor: scope extension and international reactions
Several converging signals warrant close attention:
– The European Commission has formally launched work on a possible extension of the CBAM scope to so-called “downstream” products, i.e. more processed goods that are nevertheless highly steel- or aluminium-intensive. Preparatory work refers to around 180 product categories, mainly industrial machinery, construction equipment, components and automotive parts, electrical equipment (cables, transformers, metal wires), and, to a lesser extent, certain household appliances (e.g. washing machines, refrigerators). The stated objective is to prevent circumvention and carbon leakage through imports of finished products. Entry into force around 2028 is being considered.
– Trade tensions are increasing with certain partners, notably China, which openly criticises CBAM as a disguised protectionist measure and is considering legal and commercial responses.
– The Commission has also announced a global review of the mechanism after the first year of operation of the definitive phase, opening the door to parameter adjustments and further scope extensions as early as 2027–2028, based on collected data and impact assessments.
Conclusion
With the entry into force of the definitive CBAM regime, and despite the fact that certificates will be purchased in 2027, 2026 marks the first year of full operational application of the mechanism, during which operators must comply with new declarative and financial obligations, in particular regarding the determination of embedded emissions.
Nevertheless, keeping ongoing efforts of CBAM-related challenges is essential, particularly with regard to:
- The organisation and reliability of emissions data;
- Contractual relationships with suppliers;
- The integration of CBAM into import processes and customs compliance frameworks.