# What proof of biomass sustainability will a CBAM verifier accept, and what is a mass balance?

Canonical: https://senseible.earth/answers/cbam-biomass-evidence-order-and-mass-balance

Use a voluntary scheme recognised by the Commission first. Next best is a proof of sustainability from the Union Database. Only if neither exists do you calculate it yourself. In every case a mass balance must track each consignment from harvest to your boiler, complete and auditable, and protected against change or loss.

## The order of preference

1. Certification under a voluntary scheme the Commission recognises.
2. A proof of sustainability from the Union Database.
3. Your own calculation, only if no proof is available.

## What a mass balance is

It is a record of quantities moving over time. Each addition or withdrawal is entered. Mixing or processing counts as taking from one consignment and adding to another. For each consignment you store the sustainability already proven and the life-cycle emissions already caused by that biomass. When a quantity goes to another party, that information goes with it.

## What it must do

- Track every criterion without gaps or double counting from the first collection point, the harvest, to use in your installation.
- Be complete and open to audit.
- Protect the data against unintended change or loss. The Commission says a simple spreadsheet is enough only in very simple cases.

## What to ask your supplier now

- Is the fuel certified under a scheme the Commission recognises?
- Can they issue a proof of sustainability for each delivery?
- What is the source: crop, residue, forestry or waste?

## What Senseible does here

Senseible reads your fuel, power and steam bills into verified emission records, so the monthly fuel quantities behind a monitoring plan are ready to hand to your verifier. Verified here means rule checks passed against the evidence. It is not third-party assurance, and a CBAM verifier still signs the report.

- [Sustainability rules by type of biomass](https://senseible.earth/answers/cbam-biomass-which-sustainability-rules-apply)
- [Biomass fuel in CBAM: proof to zero-rate it](https://senseible.earth/answers/cbam-biomass-fuel-zero-rating-proof)
- [CBAM Suite](https://senseible.earth/cbam-suite)

Sources: [European Commission, CBAM Guidance No. 3, calculation of embedded emissions](https://taxation-customs.ec.europa.eu/document/download/29b9eec7-1a4b-4eb6-ab85-96a0c9e35fd0_en?filename=Guidance%20No.%203%20-%20CBAM%20methods%20for%20the%20calculation%20of%20emissions%20embedded%20in%20goods.pdf)

Last reviewed 2026-11-04.