CBAM supplier data and evidence: collecting and standing behind it
The embedded-emissions figures at the centre of CBAM reporting mostly originate with suppliers, and each figure is only as strong as the evidence and assumptions behind it. This guide is about organising that: requesting supplier data, keeping references to the supporting documents, versioning revisions so you can reconstruct what changed, and writing down the assumptions you made. It is organisational guidance only — it does not set out emissions methodology, and CBAM Pulse does not collect, store, or verify supplier data on your behalf.
Last updated: 4 July 2026Sources: Regulation (EU) 2023/956Regulation (EU) 2025/2083European Commission — CBAM
Data and evidence are two different things
A supplier's embedded-emissions figure is the data. The documents, calculations, or references that explain where that figure came from are the evidence. CBAM reporting leans on both — a number without a traceable basis is hard to stand behind later (Regulation (EU) 2023/956).
So it helps to treat every figure as a pair: the value, and a pointer to whatever supports it.
Requesting supplier data
Supplier data tends to arrive slowly and inconsistently, so the request itself is worth structuring: identify the relevant suppliers, tell them which goods and which CN codes you mean, and ask for the emissions figures together with the supporting documentation behind them.
The separate guide on supplier emissions data covers the timing and sequencing of that collection in more detail.
Versioning what you receive
Figures get revised — a supplier sends an update, or you refine an estimate. Keeping dated versions, rather than overwriting, means you can always show which figure applied when and why it changed. That record is the practical backbone of an audit trail.
Documenting assumptions
Where actual data is not available, you may rely on an assumption. The assumption itself is normal; leaving it undocumented is the risk. Note what you assumed, why, and what would replace it once better data arrives, so the reasoning is legible to a reviewer, an adviser, or your national competent authority.
This guide does not tell you which method or values to use — that is a methodology question for the official sources and your adviser. It is about keeping whatever you decide organised and traceable.