Five error categories lead to a wrong CBAM declaration or a barred import: default values without the mark-up, omitted precursors, mixed system boundaries, a wrong CN code and no authorised CBAM declarant status. The last is not a reporting error but a bar on importing the goods at all.
No published dataset records how frequently each of these occurs, so the useful question is which errors change the figure and which block the import.
The five categories
| Error | Why it matters |
|---|---|
| Default values without the mark-up | Country-of-origin default values carry a mark-up (10 percent in 2026, 30 percent from 2028, fertilisers a flat 1 percent), and a figure stated without it understates the liability |
| Omitted precursor emissions | A complex good aggregates the production process and the embedded emissions of its precursors; omitting them leaves the figure incomplete rather than merely low |
| Mixed system boundaries | System boundaries are set per production process and goods category, and emissions outside them must not be mixed into the figure |
| Wrong CN code | Scope, applicable default values and whether indirect emissions count are all determined by the code |
| No authorised declarant status | From 2026 only an authorised CBAM declarant may import CBAM goods above the 50 tonne threshold (electricity and hydrogen have none) |
Why the CN code error propagates
The commodity code is not an administrative field. It determines whether the good is in scope at all, which default values apply, and whether indirect emissions are priced. Goods listed in Annex II are priced on direct emissions only: iron and steel (but not iron ore, CN 2601 12 00), aluminium, hydrogen and, since Regulation (EU) 2025/2083, electricity. Cement and fertilisers carry both direct and indirect. A wrong code therefore produces a figure calculated on the wrong basis, not simply filed under the wrong heading.
The status error is different in kind
The other four are errors in a document that can be corrected. The absence of authorised CBAM declarant status is a bar on the transaction. Goods cannot be released for free circulation above the threshold without it, so the failure occurs at the border rather than at the filing.
An importer that applied for authorisation by 31 March 2026 may continue importing while the national competent authority decides. Applications can still be made at any time, but later applicants have no provisional right to import.
Sources: Regulation (EU) 2023/956, Regulation (EU) 2025/2083
Four of the five are prevented at the data-preparation stage rather than at filing. CBAM solutions covers scope determination and embedded emissions calculation, and the CBAM guide sets out the boundary rules the figures must respect.