Which of our steel or aluminium CN codes must be put into one production process for CBAM?

Group them when two things are both true: the CN codes differ only in size or shape, such as width or thickness, and they are made from the same precursors in the same types, quantities and proportions. The EU Questions and Answers (4.4) then require one multifunctional production process.

The two tests, both must hold

• The CN codes differ only in size or shape. The EU text says codes for different widths or thicknesses of cast, extruded, rolled or forged products must sit in one production process.
• The products are made with the same precursors in the same types, quantities and proportions.

Where this applies

It applies to four aggregated goods categories: crude steel, iron and steel products, unwrought aluminium and aluminium products. Both tests are checked within a category.

Why it matters for your file

Without grouping, emissions are worked out separately for each 8-digit CN code (Q&A 4.2). Grouping is the mandatory exception, and Q&A 4.7 adds that an installation cannot have more than one production process for the same CN code.

Before you group, check

• List every CN code you ship, with width or thickness range.
• Write down the precursors behind each code, with tonnes per tonne of product. A code made with an extra input, or in a different mix, fails the second test.
• Keep the list with the production records. A verifier checks that goods sit in processes with no gaps or double counting.

Example with made-up tonnages: a rolling mill ships flat products in two widths

• CN code A: 40,000 t a year. CN code B: 80,000 t a year. Same billets, same mix.
• Both tests hold, so A and B form one production process.
• Direct emissions of the process: 36,000 t CO2e. Output: 40,000 + 80,000 = 120,000 t.
• The process is reported as one unit: 36,000 / 120,000 = 0.30 t CO2e per tonne.

Example numbers only. The mill gets its real figure from its own metered fuel and process data.

What Senseible does here

Senseible reads fuel, gas and electricity bills into one dated record per site, so the totals behind a production process are ready before a verifier asks for them.

• Splitting a plant into production processes
• What the verifier checks on CN codes
• CBAM data for exporters

Sources: European Commission, CBAM Questions and Answers (updated 15 October 2026), Q&A 4.2, 4.4 and 4.7

Last reviewed 2026-11-03.