Alex Wang – Senior Quality & Compliance Engineer at Welle Inspection, with 8+ years of experience in EU carbon regulations and CBAM compliance. Alex has successfully guided over 150 EU importers and China-based suppliers through CBAM reporting and emissions data collection, making him one of the most experienced practitioners in the field.
The EU Carbon Border Adjustment Mechanism (CBAM) requires importers to measure and report the embedded carbon emissions of goods imported into the European Union. Accurate cbam calculation is now essential for businesses sourcing products like iron and steel, aluminum, fertilizers, cement, hydrogen, and electricity. By using tools for cbam carbon footprint calculations and understanding how to calculate supplier emissions, companies can ensure compliance, reduce costs, and manage regulatory risk.
Understanding CBAM
CBAM meaning: CBAM is a regulatory mechanism designed to equalize carbon costs between goods produced in the EU and imported goods. Its main objectives are:
Prevent carbon leakage
Promote fair competition
Encourage decarbonization across global supply chains
Under the EU Carbon Border Adjustment Mechanism, importers are mandated to report the carbon content of their imported goods. From July 2024, the use of actual supplier data for cbam reporting becomes mandatory, replacing the default emission factors previously allowed during the transitional phase.
Accurate cbam calculation is not only a compliance requirement but also provides visibility into supply chain carbon performance, enabling strategic planning to reduce carbon intensity and associated costs.
Key Data Requirements for CBAM Calculation
Accurate CBAM calculation begins with collecting comprehensive production and supplier data. Without precise inputs, emissions calculations will be unreliable, increasing the risk of overpayment, non-compliance fines, and misrepresentation of supply chain carbon footprints.
Production Inputs
For each production process, importers should gather detailed information on the resources consumed:
- Fuel and Gas Consumption: Measured in tonnes, ideally per individual process. This includes natural gas, coke, coal, or other process-specific fuels. For example, if a steel plant uses blast furnaces and electric arc furnaces, consumption should be recorded separately for each. This ensures that direct emissions are accurately captured.
- Other Input Materials: Measured in tonnes, including raw materials like scrap metal, minerals, or additives. Accurate recording allows CBAM calculations to account for emissions embedded in these materials, especially when they contribute significantly to the product’s carbon intensity.
- Electricity Consumption: Measured in kilowatt-hours (kWh) and directly associated with production. Office or auxiliary electricity consumption should be excluded wherever possible, as CBAM only considers emissions related to the manufacturing process. For complex factories, sub-metering systems can help separate production electricity from administrative or HVAC loads.
Production Outputs
To link inputs to emissions, importers must also document outputs:
- Total Production Output: Expressed in tonnes per year or per quarter. Both options are allowed under CBAM regulations, but quarterly reporting is recommended for continuous compliance, timely adjustments, and smoother communication with EU importers.
- Net Weight and CN Code of Each Product: CN codes are the EU’s Combined Nomenclature system used for customs classification. Mapping production output to CN codes allows you to correctly assign emission factors to each imported product.
- Possible Deductions: Adjustments can be made for energy or material consumption unrelated to the main production process (e.g., office electricity or facility maintenance). These deductions ensure that emissions calculations reflect only production-related activities.
Supplier Data (Tier 2/3)
CBAM regulations require that emissions accounting extends beyond tier 1 suppliers:
- Upstream Supplier Reporting: Starting October 2024, importers must include verified emissions data from upstream suppliers (tier 2, 3, etc.). This ensures that the majority of embedded emissions—typically more than 80% for carbon-intensive goods—are based on actual measurements rather than default values.
- Default Values Allowance: Only up to 20% of the product carbon footprint can rely on default or regional factors provided by the European Commission. The use of defaults must be documented and justified.
- Practical Considerations: For industries such as steel, aluminum, and fertilizers, most emissions occur during raw material production. Importers must proactively request detailed consumption data from upstream suppliers, validate the data, and ensure traceability to avoid fines or misreporting.
Why Supplier Data Matters: Accurate how to calculate supplier emissions ensures that the final CBAM reporting reflects the full supply chain, minimizes financial exposure from CBAM certificate costs, and supports ESG and decarbonization strategies.
Step-by-Step CBAM Calculation
CBAM emissions are calculated using the formula:
Total Emissions=Weight of Goods (tonnes)×Embedded Emissions Factor (tCO₂e/t product)
This formula incorporates both direct emissions (fuel and process energy) and indirect emissions (electricity) as per Annex IV of the CBAM Regulation. All data must be based on verified supplier data starting July 2024.
Step 1 – Identify CBAM Goods
The first and crucial step in CBAM calculation is to identify all imported goods that fall under the EU Carbon Border Adjustment Mechanism. CBAM currently applies to high-carbon products such as iron and steel, aluminum, fertilizers, cement, hydrogen, and electricity. Accurately identifying these goods ensures that subsequent calculations are aligned with regulatory requirements and that your emissions reporting is complete.
To do this, importers should start by reviewing existing customs documentation and import records. These documents typically include the product name, quantity, country of production, and CN codes—the Combined Nomenclature codes used by the EU for customs classification. Recording the CN codes for each product is essential because they allow you to map each imported good to the correct emission factor later in the process.
For practical implementation, companies should create a structured CBAM goods register. This register should include:
- Product name and description
- CN code
- Country of production
- Quantity imported (annual or quarterly basis)
By maintaining a structured record, importers can simplify data mapping, reduce the risk of errors, and facilitate automated calculations using tools for CBAM carbon footprint calculations. It also provides a clear starting point for supplier engagement when requesting actual emissions data.
Step 2 – Select Appropriate Emission Data
When calculating CBAM emissions, three primary sources of emission factors can be used: primary supplier data, default factors provided by the European Commission (EC), and regional emission factors.
Primary Data Provided by Your Suppliers
This reflects the actual carbon intensity of production at the supplier’s facility. It is the most accurate source.
It is mandatory for CBAM reporting from 1st July 2024, unless obtaining the data is genuinely impossible.
Supplier data enables detailed tracking of emissions per product or production site.
Some suppliers may not yet have plant-specific data ready.
Collecting it may require coordination across multiple sites.
Default Factors Provided by the European Commission (EC)
These are standardized emission factors representing typical carbon intensity for each product.
Default factors simplify calculations and are suitable during the transitional reporting period or when supplier data is unavailable, particularly for minor components.
However, they provide no insight into geographic or supplier-specific variations.
They may underestimate or overestimate actual emissions, potentially introducing financial risk.
Regional Emission Factors Provided by EC
These are country- or region-specific averages that provide a more realistic estimate when supplier data is missing.
Regional factors are also useful for benchmarking supplier performance once actual data is obtained.
For example, aluminum from South Africa has a 76% higher carbon intensity than the EC default. Fertilizers from China are 38% higher.
Choosing the Right Data
For compliance reporting, primary supplier data should always be prioritized.
Regional factors can support decision-making and benchmarking.
Default factors can be used temporarily for interim reporting.
To minimize risk and ensure accuracy, it is important to start collecting supplier data early.
Document any assumptions when using default or regional factors.
Consider regional variations when estimating CBAM costs.
Step 3 – Map Goods to Emission Factors
Once you have decided whether to use default factors or regional averages, the next step is to map your imported goods to the corresponding emission factors.
This mapping ensures that each product is assessed using the correct emissions data.
The most effective way to perform this mapping is by using Combined Nomenclature (CN) codes, the EU’s standardized product classification system used for customs tariffs and trade statistics both within and outside the EU.
These codes already appear in your existing import and customs documentation, making them a reliable and consistent reference point.
By using CN codes to link goods to emission factors, companies can simplify calculations.
It enables automation in CBAM reporting tools and significantly reduces the risk of mapping and reporting errors.
Step 4 – Calculate Direct and Indirect Emissions
CBAM calculations require separating direct emissions from indirect emissions, as each follows a different calculation logic and data source.
Direct emissions are generated during the manufacturing process itself, mainly through fuel combustion or process-related energy use. These emissions can be calculated using either an activity-based approach, which relies on data such as fuel consumption, material input, and energy usage, or a measurement-based approach using Continuous Emission Monitoring Systems (CEMS) installed at the production facility. Measurement-based methods are generally preferred where available, as they provide higher accuracy and real-time data.
Indirect Emissions:
Primarily from electricity consumption for production activities.
Calculated using the electricity consumed multiplied by the corresponding emission factor (tCO₂e/MWh) from grid or on-site generation sources.
Indirect Emissions=Electricity Consumed (MWh)×Emission Factor (tCO₂e/MWh)
Accurately distinguishing and calculating both emission types is essential to ensure correct CBAM reporting and to avoid underestimating the embedded carbon content of imported goods.
Common Pitfalls When Calculating Direct and Indirect Emissions
Mixing calculation approaches for direct emissions without clear documentation can lead to double counting or inconsistent results.
Incorrect allocation of electricity consumption, such as excluding auxiliary processes, can underestimate indirect emissions.
Using incorrect or outdated electricity emission factors is risky, especially when switching between grid electricity and on-site generation.
Companies often underestimate the importance of data traceability and documentation.
CBAM reporting requires that assumptions, calculation methods, and data sources be clearly recorded, particularly when default or regional factors are used.
Poor documentation can create issues during audits or regulatory reviews.
Step 5 – Consolidate Emissions
Once direct and indirect emissions have been calculated, the next step is to consolidate emissions across the production flow.
The appropriate consolidation method depends on how the production processes are structured and how outputs move between them.
Bubble approach
All production processes are treated as a single system when the entire output of one process flows directly into the next without intermediate exports.
Emissions are consolidated by combining all inputs across the system and multiplying them by the relevant emission factors.
This approach simplifies calculations and is suitable for fully integrated production lines.
Process-by-process approach
Required when semi-finished products are exported to the EU at intermediate stages.
Each production process must be calculated separately, including direct emissions, indirect emissions, and emissions embedded in precursor materials supplied by upstream producers.
Provides greater transparency and traceability.
Requires more detailed data and coordination across the supply chain.
Selecting the correct consolidation approach is essential.
It ensures that emissions are neither double-counted nor omitted.
It ensures CBAM reporting accurately reflects the embedded emissions of the imported goods
Step 6 – Apply Complex Goods Rules (80/20 Rule)
For complex goods, such as aluminum alloys or semi-finished steel products, CBAM applies the 80/20 rule.
At least 80% of the embedded emissions must be based on actual data provided by suppliers.
No more than 20% may rely on default or regional emission factors.
This requirement is particularly important during the definitive phase of CBAM.
Excessive reliance on default or regional values can lead to higher reported emissions and increased exposure to CBAM certificate costs.
Applying the 80/20 rule supports regulatory compliance.
It also incentivizes early engagement with suppliers to obtain reliable, plant-specific emissions data for complex goods.
Step 7 – Phases of CBAM Calculation
- Transitional Phase (October 2023 – December 2025)
Default emission factors may be used where actual supplier data is not yet available, allowing companies to start reporting while supplier systems are still being developed
Reporting requirements are simplified and focus on emissions disclosure rather than financial settlement
No CBAM certificates need to be purchased during this phase, but inaccurate or inconsistent data can create risks for the definitive phase
This phase should be used to establish internal CBAM workflows, validate CN code mappings, and engage suppliers on future data requirements
- Definitive Phase (From 2026 onwards)
Verified, plant-specific emissions data provided by suppliers becomes mandatory for CBAM reporting, with limited exceptions
Reported embedded emissions are directly linked to the EU ETS carbon price, determining the number and cost of CBAM certificates to be purchased
Use of default or regional values is heavily restricted, particularly for complex goods subject to the 80/20 rule
Any data gaps, incorrect assumptions, or overreliance on fallback values can result in higher CBAM costs and increased compliance exposure
Need help calculating your CBAM emissions accurately?
CBAM Reporting and Compliance for EU Importers
Reporting Requirements
Importers must report:
- Fuel and gas consumption
- Material inputs per process
- Electricity consumption
- Total production output
- CN codes of exported products
All data must cover tier 1 and tier 2 suppliers, with a minimum of 80% of emissions based on actual data. Overreliance on default factors can trigger fines ranging from €10–50 per ton CO₂e.
Benefits of Accurate CBAM Reporting
Regular, accurate, and fully compliant CBAM emission reporting based on real factory data provides multiple benefits for both EU importers and international manufacturers:
Ensures compliance and avoids fines
Accurate reporting of fuel, electricity, material inputs, and CN codes prevents regulatory penalties.
Helps maintain smooth relationships with EU clients.
Companies can perform quarterly measurements without relying solely on complex EU templates, reducing administrative burden.
Reduces CBAM certificate costs using verified data
Reporting actual supplier emissions rather than default or regional values can significantly lower CBAM certificate costs.
Default factors are based on the highest-emitting 20% of EU facilities and are expected to increase over time.
Verified data is therefore financially advantageous.
Supports decarbonization strategies across the supply chain
Transparent emission data allows companies to identify high-carbon processes.
Enables optimization of production.
Facilitates targeted decarbonization initiatives, including adoption of renewable energy.
Improves ESG credibility with EU clients
Providing verified carbon footprints enhances corporate environmental, social, and governance (ESG) credibility.
Strengthens trust and perception of quality in the EU market.
Provides transparency for strategic decision-making
Access to reliable emission data allows forecasting of carbon-related costs.
Helps assess exposure to price fluctuations in electricity or natural gas.
Supports informed decisions on procurement, production planning, and supply chain optimization.
FAQ – People Also Ask
Q1: Can default factors be used after July 2024?
A: Only if actual supplier data is impossible to obtain.
Q2: How to calculate indirect emissions?
A: Multiply electricity consumed by the appropriate emission factor.
Q3: What is the 80/20 rule?
A: At least 80% of embedded emissions in complex goods must come from actual data.
Q4: How to reduce CBAM costs?
A: Use verified supplier data instead of default or regional averages.
Conclusion
Proper cbam calculation is now critical for EU importers to comply with the EU Carbon Border Adjustment Mechanism. By collecting verified supplier data, consolidating emissions, and using tools for cbam carbon footprint calculations, companies can ensure accurate cbam reporting, minimize CBAM-tax exposure, and strengthen ESG performance. Following this structured approach allows businesses to navigate regulatory requirements effectively, reduce financial risk, and maintain trusted relationships with EU clients.