EU CBAM — Methodology and Calculation Approach
The EU’s Carbon Border Adjustment Mechanism turns a customs declaration into a carbon-accounting exercise: every tonne of covered goods crossing the EU border now carries an embedded-emissions figure that must be calculated, reported, and — from the definitive period — paid for.
Get the embedded-emissions calculation wrong and you are not mis-stating a voluntary inventory; you are mis-filing a regulatory declaration with financial and customs consequences.
CBAM embedded emissions = (attributed direct + indirect emissions of the production process) ÷ (mass of goods produced), then × tonnes imported. Use verified actual producer data where available; fall back to published default values otherwise.
Step-by-step method for calculating and reporting embedded emissions under the EU Carbon Border Adjustment Mechanism (CBAM). Covers the six covered sectors and their CN-code scope, the direct-plus-indirect embedded-emissions formula, the actual-data-versus-default-value decision, the transitional quarterly report versus the definitive-period annual declaration, the free-allocation phase-down schedule, and the carbon-price-already-paid deduction. Aligned to Regulation (EU) 2023/956 and Commission Implementing Regulation (EU) 2025/2621.
A methodology page is the execution layer — it takes the concept from the glossary, the rules from the regulation, and the default factors from the data layer, and tells you exactly how to convert an import line into a reportable embedded-emissions figure. If your goods are already confirmed in scope, jump to the embedded-emissions formula or the worked examples.
Pre-check — are your goods in CBAM scope?
CBAM covers six sectors, identified by Combined Nomenclature (CN) code at the point of import. Five carry Annex I direct CN-code default tables; electricity is handled separately via Annex II per-country indirect factors. If your CN code is not listed in Annex I of the Regulation, the good is out of scope — confirm before building any inventory.
cbam.country.<iso3>.7201…cbam.country.<iso3>.2523_10_00.grey_clinkerreporting.cbam.indirect.<country>Two regime phases — the obligation changed shape in 2026
CBAM has two distinct operating modes. The transitional period (1 October 2023 – 31 December 2025) was reporting-only: quarterly reports of embedded emissions, no financial charge. The definitive period (from 2026) adds the financial layer — authorised declarants surrender CBAM certificates against verified embedded emissions. Both modes use the same embedded-emissions calculation; what differs is cadence, verification stringency, and whether money changes hands.
Quarterly CBAM report — reporting only
A CBAM report submitted to the CBAM Transitional Registry each quarter, due one month after quarter-end. Reports embedded direct and indirect emissions per good. No certificate purchase, no financial charge. Default values could be used without the definitive-period ceiling. This phase is historical — retained here for context and for late-correction obligations.
Annual CBAM declaration + certificate surrender
Only an authorised CBAM declarant may import covered goods. An annual CBAM declaration reports verified embedded emissions for the prior calendar year; CBAM certificates are surrendered to match. Embedded emissions need third-party verification, default-value reliance is capped, and the surrender price tracks the EU ETS allowance price, net of free allocation and any carbon price already paid in the country of origin.
When to Use This Methodology
- You import iron & steel, cement, fertilisers, aluminium, hydrogen, or electricity into the EU customs territory
- You need to calculate embedded direct and indirect emissions for a CBAM report or declaration
- You are deciding between verified actual producer data and published default values
- You are reconciling a CBAM obligation against the EU ETS allowance price and free-allocation phase-down
- You are aligning CBAM figures with a wider CSRD ESRS E1 or EU Taxonomy disclosure
- Your imported CN code is not enumerated in Annex I of the CBAM Regulation — the good is out of scope
- You are calculating a corporate GHG inventory under the GHG Protocol — CBAM embedded emissions sit outside the GHG Protocol scopes and must not be summed into a Scope 1/2/3 total
- You are an EU domestic producer covered by the EU ETS directly — CBAM applies to imports, not to EU-produced goods
- You import below the consignment de-minimis threshold for negligible-value goods
Every CBAM factor is tagged scope = outside_scopes by construction. A CBAM embedded-emissions figure is a regulatory-reporting-tier value for the CBAM declaration only — it is not a Scope 1, 2, or 3 figure and must never be added into a corporate inventory total. If you also report under CSRD or the GHG Protocol, keep the CBAM number in its own ledger and reference it, do not consolidate it. Mixing the two double-counts emissions and corrupts both filings.
Step 1 — Determine Goods in Scope (CN Codes & the Six Sectors)
CBAM scope is defined by Combined Nomenclature code, not by material description. The same metal can be in scope as one CN code and out of scope as another. Before any calculation, map every import line to its 8-digit CN code and check it against Annex I of Regulation (EU) 2023/956.
The six CBAM sectors and their default-value source
| Sector | CN / HS coverage | Default source | Embedded emissions counted |
|---|---|---|---|
| Iron & steel | HS Ch 72, 73 — pig iron, DRI, crude steel, ferro-alloys, downstream articles | Annex I direct, by country & CN code | Direct (+ indirect during transitional; indirect treatment changes in definitive period) |
| Cement | HS Ch 25 — clinker, cement, aluminous cement, calcined clay | Annex I direct | Direct process + combustion (calcination is the dominant term) |
| Fertilisers | HS Ch 28, 31 — nitric acid, ammonia, urea, nitrogenous & mixed fertilisers | Annex I direct | Direct combustion + process N₂O (nitric acid) + ammonia feedstock |
| Aluminium | HS Ch 76 — unwrought aluminium and downstream articles | Annex I direct | Direct (incl. smelting PFCs) + indirect (electricity-intensive) |
| Hydrogen | HS Ch 28 — hydrogen | Annex I direct | Direct; production route (grey/blue/electrolytic) dominates |
| Electricity | HS 2716 — electrical energy | Annex II per-country indirect (tCO₂e/MWh) | Indirect only — no Annex I direct default table exists for electricity |
Cement, fertilisers, hydrogen, iron & steel, and aluminium each carry an Annex I default emission factor per (country, CN code) in tonnes CO₂e per tonne of good. Electricity is the exception: its default comes from the Annex II per-country indirect factor in tonnes CO₂e per MWh. Do not look for an Annex I direct default for an electricity import — it does not exist, and the embedded emissions of imported electricity are indirect by definition.
The default factors above are the regulatory shortcut; the underlying process-emission methodologies are what an installation uses to compute its actual embedded emissions. GreenCalculus publishes these for every CBAM good with an Annex I direct table: cement & lime calcination, iron & steel process emissions, aluminium smelting PFCs, and the nitric-acid N2O and ammonia feedstock routes behind fertilisers in chemical-industry process emissions.
Precursors and the aggregation rule
A finished CBAM good often embeds the emissions of upstream CBAM goods. Crude steel embeds the emissions of the pig iron and DRI feeding it; a downstream steel article embeds the crude steel. The embedded emissions of a complex good are the sum of its own production-process emissions plus the embedded emissions of its CBAM precursors, allocated by mass.
This means you cannot calculate a downstream good in isolation — you need each precursor’s embedded figure first, then aggregate. Where a precursor’s actual data is unavailable, its default value is used in the aggregation, and the same actual-versus-default decision (Step 3) applies at each precursor layer.
Working through a multi-precursor steel article line by line? An interactive CBAM embedded-emissions calculator is on the GreenCalculus roadmap — until it ships, the worked examples below show the aggregation by hand.
Step 2 — Calculate Embedded Emissions (Direct + Indirect)
Embedded emissions are specific emissions per tonne of good, derived from the attributed emissions of the production process divided by the mass of goods that process produced over the reporting period. Direct and indirect components are calculated separately and reported separately.
Indirect embedded emissions follow the same shape, replacing the direct attributed-emissions term with electricity consumption × the applicable electricity emission factor:
Total embedded emissions of an import line = (SEEdirect + SEEindirect) × tonnes imported. The total reported per declaration is the sum across all import lines of covered goods.
What counts as “the production process” is sector-specific: for cement the dominant term is calcination process CO₂, for fertilisers it is process N₂O from nitric acid plus the ammonia feedstock, for aluminium it includes smelting PFCs, and for hydrogen the production route sets almost everything. The system boundary and the monitoring rules per sector are set out in the CBAM Implementing Regulation’s monitoring methodology annexes — apply the boundary for your specific good, do not generalise across sectors.
Step 3 — Actual Data vs Default Values
The embedded-emissions figure can come from one of two sources: verified actual data from the installation that produced the good, or published default values. The Regulation’s preference order is unambiguous — actual data first, defaults only as a fallback — and the definitive period adds a ceiling on how far defaults can carry you.
cbam.country.ind.2523_10_00.grey_clinker = 1.39 tCO₂e/t.
Definitive period: default-value reliance is capped — defaults cannot be used indefinitely or beyond the permitted share of an installation’s declaration.
oth catch-all country default for that CN code. cbam.country.oth.2507_00_80.calcined_clay = 0.21 tCO₂e/t.
The oth bucket is the fallback when your supplier’s production country is not separately represented in the default tables.
reporting.cbam.indirect.<country>.
Electricity has no direct default — its embedded emissions are indirect by construction. Contractual/actual factors may be used only where the eligibility conditions in the Regulation are met.
In the transitional period defaults could be used freely. In the definitive period the Regulation caps default-value reliance: defaults are intended as a fallback where actual verified data genuinely cannot be obtained, not as a routine substitute. An importer who leans on defaults indefinitely faces both a compliance challenge and, frequently, a higher cost — default values are often conservative (set high) precisely so that obtaining actual data is the rational choice. Plan to move to verified actual data from your suppliers.
Step 4 — Assemble the CBAM Report (Transitional) or Declaration (Definitive)
Reporting cadence and deadlines
| Aspect | Transitional (2023–2025) | Definitive (from 2026) |
|---|---|---|
| Submission | Quarterly CBAM report | Annual CBAM declaration (for the prior calendar year) |
| Deadline | One month after the end of each quarter | By 31 May of the year following the import year (per current Regulation timing) |
| Who files | Reporting declarant (importer or indirect customs representative) | Authorised CBAM declarant only — prior authorisation required to import |
| Verification | Not required for the report | Embedded emissions verified by an accredited verifier |
| Financial charge | None | CBAM certificates surrendered against verified embedded emissions |
| Default-value use | Permitted without ceiling | Capped — fallback only, subject to the Regulation’s limits |
Worked examples
Three calculations, each using the actual-vs-default decision from Step 3. The first two show actual verified data on the left and the published default on the right; the third shows an electricity import, which is indirect-only via Annex II. All default values are hardcoded from Commission Implementing Regulation (EU) 2025/2621 Annex tables; all arithmetic reconciles to the stated inputs.
Good: pig iron (CN 7201) from China | Quantity: 500 t
Default factor (Annex I): 1.66 tCO₂e/t | Supplier actual (verified): 1.42 tCO₂e/t Direct embedded emissions only for this line. Default value: cbam.country.chn.7201.pig_iron_spiegeleisen = 1.66. Hardcoded per IR (EU) 2025/2621.
Good: grey clinker (CN 2523 10 00) | Quantity: 2,000 t
From India (listed): 1.39 tCO₂e/t | From Korea (listed): 0.88 tCO₂e/t Default values: cbam.country.ind.2523_10_00.grey_clinker = 1.39; cbam.country.kor… = 0.88. Country-specificity matters. Hardcoded per IR (EU) 2025/2621.
oth catch-all default for the CN code applies instead — for calcined clay (CN 2507 00 80) that is 0.21 tCO₂e/t. Using oth when a country-specific value exists, or vice versa, is a common mis-declaration.Good: electricity (CN 2716) | Quantity: 50,000 MWh
Annex II per-country indirect factor: applied per country of origin (tCO₂e/MWh) Electricity has no Annex I direct default. Factor source: reporting.cbam.indirect.<country> (Annex II, IEA-licensed). Illustrative factor 0.45 tCO₂e/MWh used below — substitute the actual Annex II value for the origin country.
Step 5 — Definitive Period: Certificates, Free-Allocation Phase-Down & Carbon-Price Offset
In the definitive period the embedded-emissions figure becomes a financial liability. The number of CBAM certificates to surrender is the verified embedded emissions, adjusted by two reductions: the EU ETS free-allocation share still granted to EU producers (phased down over time), and any carbon price already paid in the country of production.
Free-allocation phase-down — why the obligation rises over time
CBAM and the EU ETS are designed to hand over from one to the other. As EU ETS free allocation to domestic producers is withdrawn, the CBAM reduction shrinks by the same proportion — so the share of embedded emissions an importer must cover with certificates rises year on year until free allocation reaches zero and CBAM applies to the full embedded figure. The schedule below is the published phase-down trajectory; treat the percentages as the CBAM-applicable share (i.e. 1 − free-allocation share).
Indicative phase-down trajectory for the CBAM-applicable share (1 − free-allocation share) per the published schedule under Regulation (EU) 2023/956 as amended. Free allocation reaches zero in 2034, at which point CBAM applies to the full embedded figure. Verify the operative year’s percentage against the current consolidated Regulation before filing — the trajectory has been subject to legislative amendment.
The carbon-price-already-paid deduction
If a carbon price was effectively paid on the embedded emissions in the country of production — for example through that country’s own ETS or carbon tax — the importer may deduct it from the CBAM obligation, with documentary evidence. The deduction prevents double-charging the same tonne of CO₂. It is evidence-driven: without acceptable proof of the price paid and that it was not rebated, no deduction is allowed.
The CBAM certificate price tracks the EU ETS allowance price, so the import obligation and the domestic compliance cost converge on the same per-tonne carbon price. The two reductions in the surrender formula — free-allocation share and carbon-price-paid — exist to keep imported and EU-produced goods on a level footing as free allocation winds down. See the EU ETS reference for the allowance-price mechanics that set the CBAM certificate price.
CBAM vs EU ETS — How the Two Interlock
| Dimension | EU ETS | CBAM |
|---|---|---|
| Applies to | EU-based installations producing covered goods | Imports of covered goods into the EU |
| Instrument | EU allowances (EUA), auctioned + freely allocated | CBAM certificates, priced off the EUA price |
| Emissions basis | Actual monitored installation emissions | Embedded emissions of the imported good (actual or default) |
| Free allocation | Granted to exposed sectors, phased down | Mirrors the phase-down — CBAM-applicable share rises as ETS free allocation falls |
| Price | Market-determined EUA secondary price | Pegged to the EUA price (weekly average basis) |
| Purpose | Cap-and-trade decarbonisation of EU industry | Carbon-leakage protection — equalise carbon cost on imports |
The clean mental model: CBAM is the import-side mirror of the EU ETS. The EU ETS prices the carbon of EU-produced goods; CBAM prices the carbon of imported goods at the same rate, with the free-allocation phase-down ensuring the two converge rather than overlapping. An EU ETS allowance-price spike feeds directly into the CBAM certificate price the following week.
What a Calculator Handles vs What You Decide
A CBAM calculator automates the mechanical arithmetic. The upstream judgements — CN-code classification, actual-vs-default sourcing, precursor mapping — are yours to make before any tool can help.
- SEE_direct and SEE_indirect computation from entered attributed emissions and activity level
- Precursor aggregation by mass once each precursor SEE is supplied
- Default-value lookup by (country, CN code) for the five Annex I sectors
- Annex II per-country indirect factor lookup for electricity
- Total embedded emissions × tonnes imported, summed across import lines
- Definitive-period certificate count with free-allocation share and carbon-price-paid deduction
- CN-code classification: is the good actually in Annex I scope, and under which code?
- Actual vs default: do you have verified producer data, or are you on defaults?
- Country specificity: listed country default, or the
othcatch-all? - Precursor map: which CBAM precursors does the finished good embed, and at what mass?
- Carbon-price-paid evidence: can you document a price effectively paid at origin?
- Verification status: is your actual data verifier-approved for the definitive period?
Error Traps — With Calculable Consequences
| Error | What happens | Consequence | How to avoid |
|---|---|---|---|
| Looking for an Annex I direct default for electricity | Electricity has no Annex I CN-code direct table; its defaults are Annex II per-country indirect. | No factor found, or wrong annex applied A direct-emissions line on an electricity import is a structural error — electricity is indirect-only. |
Use reporting.cbam.indirect.<country> (Annex II) for electricity; never the Annex I grid. |
| Summing CBAM embedded emissions into a GHG Protocol inventory | CBAM figures are tagged outside_scopes; adding them to Scope 1/2/3 double-counts. |
Corrupted corporate inventory + CBAM filing Two regulatory ledgers contaminated at once; CSRD/GHG Protocol totals overstated. |
Keep CBAM in its own ledger. Reference it in CSRD narrative if needed; never consolidate the number. |
| Applying one country’s default to another country’s import | Default emission factors are country-specific per CN code. | Up to ~58% mis-statement (Ex. 2) Grey clinker India 1.39 vs Korea 0.88 — same good, 1,020 tCO₂e apart on 2,000 t. |
Read the country-specific row; use oth only when the production country isn’t listed. |
| Treating defaults as a permanent basis in the definitive period | Definitive-period default reliance is capped; defaults are a fallback only. | Compliance challenge + higher cost Defaults are set conservatively high (Ex. 1: +16.9%) — ~€9,600 extra at €80/t on one line. |
Obtain verified actual data from suppliers; plan the transition off defaults early. |
| Omitting precursor embedded emissions | Downstream goods embed their CBAM precursors’ emissions; counting only the final process understates. | Material understatement of embedded total A steel article without its crude-steel precursor misses the largest emissions term. |
Map every CBAM precursor and aggregate by mass before declaring the finished good. |
| Claiming a carbon-price-paid deduction without evidence | The origin-country carbon-price deduction requires documentary proof it was paid and not rebated. | Deduction disallowed on audit Certificate shortfall surfaces later, with penalty exposure. |
Hold evidence of the price effectively paid before claiming the deduction; do not assume eligibility. |
| Using the wrong free-allocation-year percentage | The phase-down share changes annually and has been amended legislatively. | Certificate count off by the year delta Applying a prior year’s share misprices the surrender obligation. |
Read the operative year’s CBAM-applicable share from the current consolidated Regulation before filing. |
Methodology Metadata — For Customs Documentation
Copy into your CBAM declaration methodology record. Confirm the operative regulation version and the year’s free-allocation share against the current consolidated text before each filing.
Frequently Asked Questions
CBAM covers six sectors identified by Combined Nomenclature code at import: iron & steel, cement, fertilisers, aluminium, hydrogen, and electricity. Five of these — cement, fertilisers, hydrogen, iron & steel, and aluminium — carry Annex I direct default emission factors per (country, CN code). Electricity is handled separately: it has no Annex I direct table, and its defaults come from Annex II per-country indirect factors in tCO₂e/MWh. Scope is defined strictly by CN code — if your import’s CN code is not in Annex I of Regulation (EU) 2023/956, there is no CBAM obligation, regardless of the material.
Specific embedded emissions equal the attributed emissions of the production process (direct combustion and process emissions, plus the embedded emissions of any CBAM precursors) divided by the mass of goods that process produced. Indirect embedded emissions equal electricity consumed per tonne × the applicable electricity emission factor. Total embedded emissions for an import line = (direct + indirect specific embedded emissions) × tonnes imported, summed across all covered lines. Direct and indirect components are calculated and reported separately. Use verified actual producer data where available; fall back to the published default values otherwise.
Default values are a fallback for when verified actual producer data cannot be obtained. In the transitional period (2023–2025) defaults could be used without a ceiling. In the definitive period (from 2026) default-value reliance is capped — defaults are intended for genuine data gaps, not as a routine substitute. Defaults are also typically set conservatively high, so they usually overstate emissions relative to actual data; in the worked steel example the default reports 16.9% more than the verified figure. The practical implication: obtaining verified actual data from suppliers usually both improves compliance standing and lowers certificate cost.
The transitional period (1 October 2023 – 31 December 2025) was reporting-only: a quarterly CBAM report of embedded emissions, due one month after each quarter-end, with no financial charge and no verification requirement. The definitive period (from 2026) adds the financial and authorisation layers: only an authorised CBAM declarant may import covered goods; an annual CBAM declaration reports the prior year’s verified embedded emissions; embedded emissions need third-party verification; default-value reliance is capped; and CBAM certificates are surrendered against the verified figure, priced off the EU ETS allowance price. The embedded-emissions calculation itself is the same across both periods.
CBAM is the import-side mirror of the EU ETS. The EU ETS prices the carbon of goods produced in the EU; CBAM prices the carbon of imported goods at the same rate, with the CBAM certificate price pegged to the EU allowance price. The two are linked through the free-allocation phase-down: as EU ETS free allocation to domestic producers is withdrawn, the CBAM-applicable share of embedded emissions rises by the same proportion, reaching the full embedded figure when free allocation hits zero in 2034. Any carbon price already paid in the country of production can be deducted from the CBAM obligation with evidence, preventing double-charging.
No. CBAM embedded-emissions factors are regulatory-reporting-tier values tagged as sitting outside the GHG Protocol scopes. They exist for the CBAM declaration only and must not be summed into a corporate GHG Protocol inventory or a CSRD ESRS E1 total — doing so double-counts emissions and corrupts both filings. If imported CBAM goods also appear in your Scope 3 purchased-goods category, that Scope 3 figure is calculated under GHG Protocol rules with its own emission factors; the CBAM number is a separate, parallel ledger you reference rather than consolidate.
In the definitive period the certificates to surrender equal verified embedded emissions × the CBAM-applicable share for that year, minus any documented carbon price already paid at origin. The CBAM-applicable share is one minus the EU ETS free-allocation share still granted to EU producers, and it rises over time as free allocation is withdrawn — from a small share in 2026 to the full embedded figure once free allocation reaches zero in 2034. Because the trajectory has been amended legislatively, always read the operative year’s percentage from the current consolidated Regulation rather than relying on a prior year’s figure.