What changes between the CBAM transitional and definitive periods

The difference between CBAM’s two periods is not merely “paying money”. Who may act as declarant, how data must be verified, how often filings are made and what happens on error all differ. The transitional period was practice; the definitive period is enforcement.

Filing frequency and declarant

In the transitional period the importer filed a CBAM report within one month after each calendar quarter. In the definitive period the declaration becomes annual, consolidating all imports from the previous calendar year into one CBAM declaration. Certificate purchasing, however, continues through the year — so cash flow is decoupled from the annual filing.

The bigger change is on the declarant side. In the definitive period, importing a CBAM good requires prior status as an “authorised CBAM declarant”. Without it, customs clearance cannot complete. For an exporter the consequence is blunt: if your customer has not registered, your shipment stops at the border — however flawless your emissions data.

The verification requirement

In the transitional period, independent verification of declared emissions was not mandatory; the importer could pass on what the producer told them. In the definitive period, declarations based on actual data are expected to carry accredited verification. Verifiers come from the same accreditation framework as bodies accredited for ETS verification.

For a producer that translates into calendar. Verification happens after data collection and typically takes six to ten weeks. Calling a verifier two weeks before the annual filing date does not work; the process starts with the previous year’s data collection plan.

The phase-out of free allocation

The CBAM liability rises symmetrically with the free ETS allocation an EU producer still receives. While EU producers get free allocation, the number of certificates an importer surrenders is reduced by the corresponding share. As free allocation phases down to zero, the CBAM liability rises to its full rate. The burden in the early years does not represent the eventual burden.

For planning, that means calculating today’s CBAM cost at today’s rate and concluding it is “manageable” is misleading. Investment decisions should be assessed against the cost in the years when the allocation rate approaches zero.

The penalty regime

In the transitional period, administrative fines applied to missing or late reports, and in practice enforcement moved from warning to fine. In the definitive period the penalty for each certificate not surrendered follows the same logic as the ETS excess emissions penalty, and paying the penalty does not extinguish the obligation — the missing certificates are still surrendered. That is what makes the penalty bite.