One line makes many bar sizes. Do we need separate UK CBAM figures?
Usually one. HMRC's UK CBAM guidance says steel goods under different CN codes that differ only in size or shape, made from the same precursors in the same proportions, must be grouped into one multifunctional production process. Emissions are then shared by tonnes across those codes, so each size carries the same intensity.
When sizes must be grouped
- Sizes under the same CN code: one functional unit, one figure.
- Different CN codes that differ only in size or shape, such as width or thickness: grouped, if the precursors are the same in type, quantity and proportion.
- The grouped output is split pro rata by tonnes per CN code.
When they stay apart
A different alloy content fails the same-proportions test. HMRC's example is stainless steel with nickel below 2.5%, grouped separately from grades at 2.5% or more. Goods made through the same physical steps, such as hot then cold rolling, may also be grouped even when the rule does not require it.
Aluminium
Aluminium goods made through the same process may be grouped into one multifunctional production process with a single emissions intensity for each good.
What to keep
Output in tonnes per CN code per month, from your production log or dispatch records, so each figure can be traced to the code on the invoice.
What Senseible does here
Senseible keeps output by product code next to the fuel and power records for the same months. We build the figure from your records and check every figure in-house; for the UK it must then be verified by a verifier accredited for UK CBAM. Have your own verifier? Send it to them.
Sources: HMRC, UK CBAM monitoring, reporting and verification technical guidance (October 2026), HMRC, Carbon Border Adjustment Mechanism (CBAM): Policy summary (updated 2 November 2026)
Last reviewed 2026-11-02.