Methodology
How the figures are computed, and under which rules
Every number Verdex produces is computed by deterministic code from a versioned methodology selected by the reporting period — not by whatever the software happens to be on the day you look. The same inputs under the same version always produce the same result, and every run carries a fingerprint over its inputs so an edit after the fact is detectable.
Three rules before any equation
- Deterministic. No model, no inference and no network call ever touches a number that ends up in a declaration. A model may propose a value read off a scanned bill; only a person may accept it, and only code computes with it.
- Nothing silently defaulted. A missing input is a typed gap with a severity and an owner, not a quietly assumed number. Where a screening default is used, it is labelled as one.
- Every figure carries its derivation. The calculation trail from source stream to specific embedded emissions is stored with the result, because a verifier audits the path, not the answer.
Version CBAM-2026.1
Effective 2026-01-01 to 2027-12-31
Legal basis
- Reg. (EU) 2023/956, CBAM Regulation, Annex IV
- IR (EU) 2025/2547, calculation methods for embedded emissions
- IR (EU) 2018/2066, EU ETS monitoring and reporting, applied by reference
- IR (EU) 2025/2621, default values
- IR (EU) 2025/2620, free allocation adjustment
- IR (EU) 2025/2546, verification
- Reg. (EU) 2025/2083, amending Reg. (EU) 2023/956
- Del. Reg. (EU) 2025/2551, accreditation of verifiers
Equations
| Equation | Applies to | Legal reference |
|---|---|---|
SEEg = AttrEmg / ALg | Simple goods, no Annex I precursors consumed | Reg. (EU) 2023/956 Annex IV |
SEEg = (AttrEmg + EEInpMat) / ALg | Complex goods, one or more Annex I precursors consumed | Reg. (EU) 2023/956 Annex IV |
AttrEmg = direct + (indirect if the sector counts it) | All production processes | IR (EU) 2025/2547 |
E = quantity x NCV x EF x oxidation_factor | Combustion source streams | IR (EU) 2018/2066 Art. 24, calculation-based approach |
E = quantity x EF x conversion_factor | Process source streams | IR (EU) 2018/2066 Art. 24 |
E = kWh / 1000 x EF_per_MWh | Purchased electricity | IR (EU) 2025/2547, indirect emissions |
EEInpMat = Σ (tonnes_i x SEE_i) | Each Annex I precursor consumed | Reg. (EU) 2023/956 Annex IV |
Default-value mark-up by year
2026: 10% · 2027: 10%
Which sectors count indirect (electricity) emissions
cement, fertilizer — for every other covered sector only direct emissions carry the charge. Getting this backwards inflates a steel figure by roughly a third, which is why it is registry data rather than an assumption in code.
Notes
- Definitive regime from 1 January 2026; first declaration covering 2026 imports due 30 September 2027.
- Default value mark-up is 10% through 2027.
- Certificate sales open 1 February 2027. A 50% quarterly holding obligation applies from 2027.
Version CBAM-2028.1
Effective 2028-01-01 onward
Legal basis
- Reg. (EU) 2023/956, CBAM Regulation, Annex IV
- IR (EU) 2025/2547, calculation methods for embedded emissions
- IR (EU) 2018/2066, EU ETS monitoring and reporting, applied by reference
- IR (EU) 2025/2621, default values
- IR (EU) 2025/2620, free allocation adjustment
- IR (EU) 2025/2546, verification
- Reg. (EU) 2025/2083, amending Reg. (EU) 2023/956
- Del. Reg. (EU) 2025/2551, accreditation of verifiers
Equations
| Equation | Applies to | Legal reference |
|---|---|---|
SEEg = AttrEmg / ALg | Simple goods, no Annex I precursors consumed | Reg. (EU) 2023/956 Annex IV |
SEEg = (AttrEmg + EEInpMat) / ALg | Complex goods, one or more Annex I precursors consumed | Reg. (EU) 2023/956 Annex IV |
AttrEmg = direct + (indirect if the sector counts it) | All production processes | IR (EU) 2025/2547 |
E = quantity x NCV x EF x oxidation_factor | Combustion source streams | IR (EU) 2018/2066 Art. 24, calculation-based approach |
E = quantity x EF x conversion_factor | Process source streams | IR (EU) 2018/2066 Art. 24 |
E = kWh / 1000 x EF_per_MWh | Purchased electricity | IR (EU) 2025/2547, indirect emissions |
EEInpMat = Σ (tonnes_i x SEE_i) | Each Annex I precursor consumed | Reg. (EU) 2023/956 Annex IV |
Default-value mark-up by year
2028: 30%
Which sectors count indirect (electricity) emissions
cement, fertilizer — for every other covered sector only direct emissions carry the charge. Getting this backwards inflates a steel figure by roughly a third, which is why it is registry data rather than an assumption in code.
Notes
- Default value mark-up rises to 30% from 2028, widening the gap between defaults and measured data.
Calculation methods
Two calculation-based approaches are implemented: the standard method per source stream — quantity × net calorific value × emission factor × oxidation factor for combustion, quantity × emission factor for process streams — and mass balance for integrated works, where carbon entering the boundary minus carbon leaving it, times 44/12, gives the emissions a blast-furnace route cannot express as separate streams. Attribution is per production process, never plant-total divided by plant output, and a multi-line plant that reports only its cleanest line is refused — the anti-circumvention rules prohibit exactly that.
Check the arithmetic yourself
Two fully specified reference plants — a scrap-EAF mill and an integrated BF-BOF works — are published with every intermediate figure and recomputed live on the golden dataset page. Every field the product collects, with its validation rule and the regulation behind it, is published in the data dictionary.
What this methodology does not claim
Verdex is not an accredited verifier and produces no figure that alone satisfies a CBAM declaration. Under Reg. (EU) 2023/956, actual embedded emissions count once verified by a body accredited under Reg. (EC) 765/2008 by an EU or EEA national accreditation body, and the declaration is filed by the EU importer. Verdex prepares the calculation, the evidence and the monitoring plan that verification starts from. The golden dataset has not yet been reviewed by an external practitioner, and the page that publishes it says so.