Can a mass-balance low-carbon steel certificate lower our CBAM figure?
No. The EU's CBAM Q&A 4.13 says the mass balance chain of custody model cannot be used as proof of traceability in CBAM. A certificate that allocates low-carbon steel on paper does not lower the figure. Embedded emissions are reported per CN code, as a weighted average where batches mix.
What the Q&A says
The question was asked about fertiliser batches blended in one tank. The answer covers CBAM as a whole: mixed batches of one CN code are reported as a weighted average of the functional unit, and mass balance cannot prove traceability.
What your precursor figure is
The supplier installation's verified embedded emissions for the CN code you bought, averaged over everything it made under that code in the period. The low-carbon share allocated to your invoice does not change it.
What does lower it
- Buying from an installation whose verified figure for the code is lower.
- Physical changes at your supplier, more scrap or cleaner reduction, that lower the average for every tonne.
- Better yield at your own plant, so you use less steel per tonne of product.
Where the certificate may still help
A buyer programme or product footprint standard may accept mass balance claims under its own rules. Check that programme. Keep the claim out of the CBAM file.
Example: 1,000 t of coil sold as low-carbon
- Supplier makes 100,000 t under one CN code at 2.2 t CO2e per tonne
- It sells 20,000 t as 0.5 t CO2e per tonne by mass balance
- Your 1,000 t in the CBAM figure: 1,000 x 2.2 = 2,200 t CO2e, not 1,000 x 0.5 = 500 t
Example figures.
What Senseible does here
Senseible's CBAM Suite carries each bought precursor at its supplier's verified figure or the EU default value, never at a mass balance claim. We build it from your records, check every figure in-house, and an accredited verifier we partner with signs it off. Have your own verifier? Send it to them.
Sources: European Commission, CBAM Questions and Answers (15 October 2026), question 4.7, 4.8 and 4.13
Last reviewed 2026-11-01.