CBAM guide · 2026
CBAM Reporting in 2026: How the Definitive Phase Works
2026 is the year the Carbon Border Adjustment Mechanism changes shape for EU importers. The quarterly reporting of the transitional period ends, and the definitive (or "permanent") phase begins — with an annual, third-party-verified declaration and, from 2026, exposure to the cost of CBAM certificates. This guide explains what changed and how to prepare your embedded-emissions data.
The short answer
In 2026 CBAM moves from quarterly transitional reports to an annual, verified declaration. The final quarterly report covers Q4 2025 and is due by 31 January 2026. After that, importers no longer file quarterly — instead you submit a single annual CBAM declaration, and the first one (covering the 2026 calendar year) is due by 30 September 2027. From 2026 the definitive phase also introduces the purchase and surrender of CBAM certificates to cover the embedded emissions of in-scope imports, so the data is no longer just a reporting exercise — it drives a real cost. To prepare, confirm your goods are in scope, collect verified embedded-emissions data from non-EU suppliers, apply the EU methodology (using default values only where permitted), and track your exposure quarterly so the annual bill is not a surprise. A supplier emissions portal with one auditable data backbone makes this far easier than spreadsheets.
What changed for CBAM in 2026
CBAM ran a transitional, reporting-only phase from October 2023 to the end of 2025. The definitive phase that begins in 2026 turns it into a financial mechanism. The practical shifts for importers are:
Quarterly reporting ends
The transitional period closes with the Q4 2025 report, due by 31 January 2026. That is the final quarterly CBAM report you file.
An annual verified declaration replaces it
From the definitive phase you submit one annual CBAM declaration per calendar year, and embedded emissions generally must be verified by an accredited verifier rather than self-declared.
CBAM certificates create a real cost
In the definitive phase authorised CBAM declarants buy and surrender certificates to cover the embedded emissions of in-scope imports, priced against the EU ETS — so emissions now carry a financial liability, not just a reporting one.
Authorised declarant status is required
Only an "authorised CBAM declarant" may import covered goods in the definitive phase, so you must secure that status before continuing to import.
CBAM rules and dates are set by the European Commission and continue to evolve (including the 2025 "Omnibus" simplification proposals). Always confirm the current obligations and thresholds for your goods with the official EU guidance before you file.
How to prepare for CBAM reporting in 2026: step by step
Follow these seven steps to move from the old quarterly habit to a definitive-phase annual declaration and keep your certificate exposure under control.
- 1
Confirm whether your imported goods are in CBAM scope
Check the CN (Combined Nomenclature) codes of what you import against the CBAM goods list. CBAM currently covers carbon-intensive sectors — iron and steel, aluminium, cement, fertilisers, hydrogen and electricity — plus certain downstream products. If none of your codes are listed, you have no CBAM obligation; if some are, scope only those goods.
- 2
Note the end of quarterly reporting (last report January 2026)
Mark that the transitional, quarterly regime is finishing. The report for the fourth quarter of 2025 is the final quarterly CBAM report and is due by 31 January 2026. File it as normal, then stop preparing quarterly returns — the obligation shifts to an annual cycle.
- 3
Understand the move to an annual verified declaration
In the definitive phase you submit a single annual CBAM declaration covering a full calendar year of imports, instead of four quarterly reports. The embedded emissions you declare generally have to be verified by an accredited third-party verifier, so build verification time into your process rather than self-reporting estimates.
- 4
Collect verified embedded-emissions data from suppliers
Ask your non-EU producers for the actual (primary) embedded emissions of the specific goods you import, including both direct and relevant indirect (electricity) emissions, calculated to the EU methodology. Use a structured supplier request — a supplier emissions portal beats email and spreadsheets — and keep evidence so the figures stand up to a verifier and the customs authority.
- 5
Apply EU methodology and default-value rules correctly
Calculate embedded emissions using the EU CBAM methodology and system boundaries. You may rely on Commission default values only where the rules allow it (for example where primary supplier data is genuinely unavailable, and within any limits on the share of default-based emissions). Default values are usually conservative, so accurate primary data typically lowers your certificate cost.
- 6
Track data quarterly internally for certificate-cost planning
Even though you only file once a year, keep measuring embedded emissions quarter by quarter internally. Multiply your in-scope embedded emissions by the expected CBAM certificate price to forecast the liability, set aside budget, and avoid a year-end surprise. This also flags data gaps with enough time to chase suppliers.
- 7
Prepare the first annual declaration due September 2027
Your first annual CBAM declaration covers the 2026 calendar year and is due by 30 September 2027. Before then, confirm you hold authorised CBAM declarant status, consolidate verified embedded emissions for all in-scope imports, reconcile the CBAM certificates you need to surrender, and assemble the supporting evidence so the submission and any audit go smoothly.
Making CBAM data manageable with CarbonTool
The hardest part of CBAM is not the form — it is getting accurate embedded-emissions figures out of non-EU suppliers and keeping them audit-ready. CarbonTool is built for exactly this: a supplier portal lets your steel, aluminium, cement, fertiliser and other suppliers submit primary data directly, while 200+ GHG-Protocol emission-source templates and a full audit trail mean every figure carries its source, unit, emission factor and data-quality level. Because it is one data backbone for CSRD, VSME, GRI, CDP and PCAF, the embedded-emissions work you do for CBAM feeds your wider CSRD reporting rather than living in a separate spreadsheet. CarbonTool is built by the BuildGreen team, has transparent pricing and a free 30-day trial — so you can start structuring supplier data today.
Related reading
Supply chain & supplier portal
Collect primary embedded-emissions data from non-EU suppliers in one structured, auditable place.
Supplier emissions data collection software
How to request, validate and store supplier emissions data without spreadsheets.
CSRD software for Europe
Reuse the same data backbone for CSRD, VSME and your wider EU reporting.
Carbon accounting glossary
Plain-English definitions of CBAM, embedded emissions, Scope 1–3 and more.
Got more questions?
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No. The quarterly reporting of the transitional period ends with the Q4 2025 report, which is due by 31 January 2026. From the definitive phase that begins in 2026 you no longer file quarterly returns — the obligation becomes a single annual CBAM declaration covering each calendar year.
The first annual CBAM declaration covers the 2026 calendar year and is due by 30 September 2027. From then on you submit one verified declaration each year covering the previous calendar year of in-scope imports.
Send each producer a structured request for the actual (primary) embedded emissions of the specific goods you import, covering direct and relevant indirect emissions calculated to the EU methodology, and keep the supporting evidence. A supplier emissions portal — like the one in CarbonTool — collects this directly from suppliers with an audit trail, which is far more reliable than email and spreadsheets and helps the figures pass third-party verification.
You may use the European Commission default values only where the rules permit — typically where genuine primary supplier data is unavailable, and within any limits on the share of emissions that may be default-based. Default values are usually set conservatively, so obtaining accurate primary data from suppliers generally reduces your CBAM certificate cost.
CBAM currently applies to carbon-intensive goods: iron and steel, aluminium, cement, fertilisers, hydrogen and electricity, plus certain downstream products. Scope is defined by CN (Combined Nomenclature) code, so check the exact codes of what you import against the official CBAM goods list rather than relying on the sector name alone.
The definitive phase from 2026 introduces the purchase and surrender of CBAM certificates to cover the embedded emissions of in-scope imports, priced against the EU ETS. This is the point at which CBAM becomes a financial liability rather than reporting only, so you should forecast the cost during 2026 even though the first annual declaration and reconciliation fall in September 2027. Confirm the precise certificate timing for your goods with the current official EU guidance.
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