The EU’s Carbon Border Adjustment Mechanism (CBAM) distinguishes between steel-processing activities that are included in the emissions calculation and those excluded from the defined production boundary. For iron and steel products, reheating, rolling, annealing and galvanising are treated as within the system boundary. Cutting, welding, plating and finishing are treated as excluded. For steel producers and downstream processors, the distinction determines which production activities and associated emissions must be reflected in reported embedded emissions.
The rules apply to rerollers, galvanisers, wire producers, fabricators, engineering teams and EU buyers. Establishing the correct boundary requires a technical assessment of the production process, including activities performed at other installations or by subcontractors. The assessment is used to determine which stages are covered for CBAM reporting purposes.
Covered and excluded transformation stages for iron and steel
The European Commission’s CBAM methodology lists reheating, remelting, casting, hot and cold rolling, forging, pickling, annealing, coating, galvanising and wire drawing among processes included within the system boundary for iron and steel products. These included stages are incorporated into the embedded-emissions calculation. In contrast, plating, cutting, welding and finishing are excluded from the applicable CBAM production boundary.
The inclusion or exclusion of specific operations affects how embedded emissions are calculated for different supply-chain roles. Where an in-scope transformation is performed at a secondary installation or outsourced before goods return to the primary installation, the activity is treated as if it had been carried out at the primary installation for the defined production process. This approach is intended to prevent changes in reporting driven solely by moving a covered stage to a subcontractor while keeping goods within the same production process.
A fabricator that performs only excluded operations can therefore have a different direct-emissions profile from a reroller or galvaniser. This applies even when both supply steel products with similar shapes and dimensions. Their CBAM calculations must reflect the activities covered by the methodology rather than treating every downstream operation identically.
Using process diagrams and records to define the boundary
Engineering teams are expected to identify the applicable production boundary on the actual process-flow diagram. Furnaces, coating lines, galvanising baths, relevant source streams and shared utilities should be linked to activities included in the calculation. This mapping supports an engineering-based representation of what is covered under CBAM.
Outsourced operations require contracts and production records that establish where work took place and how relevant data are incorporated into the emissions calculation. Companies should reassess their boundary when a production stage is relocated or subcontracted or otherwise changed. The technical assessment is intended to be completed before building emissions spreadsheets.
A boundary register should identify included and excluded activities, responsible data owners, relevant source streams and outsourced transformations. The register is used so that an accredited verifier can examine an engineering-based production model rather than relying only on financial allocations.
Implications for Western Balkan exporters with distributed production
For Western Balkan exporters where rolling, coating, galvanising and fabrication may be distributed across affiliated companies or subcontracted sites, legal entity structure alone is described as insufficient. The CBAM assessment must follow the technical transformation process, including covered activities performed away from the principal production site. The boundary determination therefore depends on where covered transformations occur.
Supplier contract requirements under MRV for steel
Supplier governance forms part of the monitoring, reporting and verification framework for steel under CBAM-related obligations. Purchase contracts should specify the producing installation, reporting period, emissions-data format, verification requirements and procedures for correcting reported information. These contract elements support consistent reporting across supply chains.
Changes in supplying plant, production route or precursor can alter the emissions value attributed to a product. If such changes occur without notifying downstream producers, carbon-cost exposure may arise after a commercial price has already been agreed. Contractual change-notification requirements are therefore described as serving both compliance needs and commercial risk management by enabling buyers and producers to reassess emissions information when underlying arrangements change.
The same boundary rules are also described as relevant to make-or-buy decisions. Outsourcing an included transformation may remain operationally appropriate but does not provide a basis for excluding that stage from the CBAM calculation. Excluded finishing operations can be assessed separately for broader product-footprint reporting or customer requirements without being incorporated into the current CBAM figure.
Linking verified emissions data to procurement and documentation
Steel buyers increasingly need to distinguish between products supported by reliable verified emissions data and those where importers may rely on default values. The distinction has commercial relevance because applicable default-value mark-ups increase during the definitive phase. Substantiated actual emissions data can reflect characteristics of cleaner feedstock or production routes.
Suppliers able to quantify differences in euros can provide buyers with a clearer basis for evaluating premiums and long-term contracts. Generic low-carbon claims do not provide evidence at the same level as emissions data linked to a specific installation, production process and reporting period. For producers, ensuring that commercial emissions figures correspond to legally applicable CBAM calculations is described as an objective.
Broader product-footprint assessments may cover additional activities beyond those included in CBAM reporting boundaries. Where such assessments extend beyond regulatory scope, they should be reported separately rather than incorporated into the current CBAM figure.
Building compliance files with CN codes, boundaries and fallback treatment
The supplier and importer need consistent underlying records to substantiate declared emissions figures. Compliance files should connect purchasing documentation with production records as well as customs and finance documentation tied to relevant installations and reporting periods. Routine industrial data, controlled assumptions and documented fallback procedures are described as tools to accommodate changes in suppliers or legal requirements without reconstructing calculations from scratch.
Before finalising a transaction or reporting period, a decision file should link CN code, precursor information, production-process boundary details, production records and verified emissions value. It should also identify who approves each assumption and document fallback treatment if preferred approaches cannot be substantiated. A fallback may lead to less favourable commercial outcomes but is intended to allow companies to assess potential exposure before challenges by a verifier or customs authority or an authorised CBAM declarant.
The control described in this context is the production boundary established by the methodology in force, rather than a company’s broader voluntary carbon-accounting approach. Correct identification of included transformations and maintenance of traceable evidence are described as necessary steps to avoid both omitted emissions and inclusion of activities outside the defined CBAM system boundary.