Production-system boundary for CBAM steel calculations
The European Commission has clarified which steel transformation activities fall within the production-system boundaries used to calculate embedded emissions under the European Union’s Carbon Border Adjustment Mechanism (CBAM). The distinction determines which processes must be reflected in embedded-emissions calculations and which remain outside the prescribed boundary, even when they occur at the same industrial site.
The guidance specifies reheating, remelting, casting, hot and cold rolling, forging, pickling, annealing, coating, galvanising and wire drawing as activities within the relevant production boundary. Plating, cutting, welding and finishing are excluded from that boundary.
CBAM methodology based on prescribed boundaries and CN classification
The Commission’s guidance frames CBAM as operating under prescribed system boundaries rather than as a conventional life-cycle carbon footprint assessment. The methodology applies boundaries linked to the production process and the relevant Combined Nomenclature (CN) classification.
As a result, physical emissions generated inside a factory do not automatically enter the embedded-emissions calculation for a specific CBAM good. Treatment depends on whether each activity falls within the applicable production-system boundary.
MRV requirements for covered versus excluded steps
For steel processors in Serbia and Southeast Europe, the boundary distinction requires monitoring, reporting and verification (MRV) systems to separate covered transformation steps from excluded operations. Metering, energy allocation and production records must distinguish activities included in the calculation from those outside it.
This separation affects how businesses demonstrate that energy and emissions data are attributed correctly. It also requires ensuring that excluded finishing activities are not incorporated into embedded-emissions calculations.
Tolling and secondary installations in the embedded-emissions boundary
The Commission also clarified how covered processes are treated when performed outside the primary installation. Where an in-scope transformation step takes place at a secondary installation or is outsourced to another company, and goods return to the primary installation afterward, the process must be treated as if it occurred at the primary installation.
The guidance indicates that contracts with toll processors and other external service providers may need to establish access to production records, energy consumption figures, fuel-use data and supporting documentation. This is particularly relevant when the equipment performing a covered operation belongs to another company.
Process-specific data for verification and operational records
Boundary rules create challenges for businesses whose carbon accounting has historically focused on corporate emissions or total plant consumption. A site-wide electricity bill alone may not provide sufficient evidence if a verifier cannot determine the share attributable to the covered production process.
The distinction also matters for technical due diligence by banks and industrial buyers. An established environmental, social and governance (ESG) reporting system does not necessarily demonstrate CBAM readiness if it cannot separate the prescribed production system from other activities at the site.
Linking transformation steps to meters, orders and material movements
For upcoming compliance cycles, industrial operators will need to connect each relevant transformation step with appropriate meters, production orders and material movements. This includes maintaining consistent records when covered processes are performed by external contractors.
The Commission’s clarification places production-process boundaries at the centre of steel-sector emissions reporting. Detailed operational data is therefore described as essential for substantiating embedded-emissions calculations under CBAM.