# Which processes sit inside a UK CBAM figure?

Canonical: https://senseible.earth/answers/uk-cbam-system-boundaries

The direct emissions of the production processes HMRC's System Boundaries Document assigns to your product, drawn to match UK ETS boundaries, plus embodied emissions of precursors for complex goods. Each production process relates to a single CN code, and several routes making goods in one aggregated goods category count as one process.

## Inside

- Combustion and process emissions at the installation.
- Emissions from making heat consumed in the process, including heat bought from a third party.
- For complex goods, the embodied emissions of relevant precursors, such as billet in bar.
- For fertilisers, N2O; for aluminium, PFCs; CO2 in every sector.

## Outside

- Indirect emissions from electricity use.
- Products returned to the same process, and waste or scrap, which are excluded from the tonnes produced.

## Process and route

An installation can hold several production processes, and a process can hold several production routes. If one site makes crude steel in both a basic oxygen converter and an electric arc furnace, both routes sit in the crude steel category, so they form one process and one figure, a weighted average across the routes. Emissions are always attributed at the process level.

## A rebar mill buying billets

- Inside: reheating furnace fuel, 600 tCO2e; embodied emissions of 10,400 t billet at 2.00000 tCO2e/t, 20,800 tCO2e.
- Outside: grid electricity for the mill motors.
- Rebar produced: 10,000 t.
- Emissions intensity: (600 + 20,800) / 10,000 = 2.14000 tCO2e/t.

Example figures.

## What Senseible does here

Senseible reads fuel, steam and precursor invoices as separate lines, so each source inside the boundary is visible. 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.

- [Electricity is not counted](https://senseible.earth/answers/uk-cbam-electricity-not-counted)
- [Many sizes, one process](https://senseible.earth/answers/uk-cbam-many-sizes-one-process)
- [CBAM Suite](https://senseible.earth/cbam-suite)

Sources: [HMRC, Carbon Border Adjustment Mechanism (CBAM): Policy summary (updated 2 November 2026)](https://www.gov.uk/government/publications/carbon-border-adjustment-mechanism-cbam-policy-summary/carbon-border-adjustment-mechanism-cbam-policy-summary), [HMRC, UK CBAM monitoring, reporting and verification technical guidance (October 2026)](https://assets.publishing.service.gov.uk/media/6ad219fe0f7b53973e02680f/CBAM_technical_guidance.pdf)

Last reviewed 2026-11-03.