CBAM actual emissions data replaces conservative default values through three steps: the exporting installation collects monitored, source-level emissions using a calculation-based or measurement-based methodology, forwards that activity data to the importer, and an accredited verifier approves the final declaration, since CBAM reporting has required actual, not estimated, figures since 1 August 2024.
Why default values cost more than actual data
The CBAM definitive regime, live since 1 January 2026, is built on specific actual embedded emissions from the producing installation. Where actual data is not supplied, country-of-origin default values from Implementing Regulation (EU) 2025/2621 apply, carrying an escalating mark-up of 10 per cent in 2026, 20 per cent in 2027 and 30 per cent from 2028, with a flat 1 per cent for fertilisers. Because those defaults are deliberately conservative, verified actual data usually lowers the declared figure and the certificate obligation. GreenSutra’s CBAM advisory team calculates embedded emissions and prepares the declaration on this basis.
Three steps to actual emissions data
Switching means the exporting installation supplies monitored, source-level emissions and activity data to the importer, the figures follow a recognised monitoring methodology set in the operational rules, and an accredited verifier approves the final CBAM declaration. Verifier registration for the definitive regime opened on 1 September 2026, so an accredited body can be appointed for the annual declaration. The move from default values to actual data follows the steps summarised below.
| Step | What happens | Basis |
|---|---|---|
| Supplier data collection | Exporting installation records source-level fuel, process and electricity data | Annex IV, Regulation (EU) 2023/956 |
| Monitoring methodology | Calculation-based approach (including mass-balance) or measurement-based approach (continuous emission monitoring) | Implementing Regulation (EU) 2025/2547 |
| Third-party verification | Final declaration approved by a verifier accredited to ISO 14065 and ISO/IEC 17029 | Delegated Regulation (EU) 2025/2551 |
When default-value use is restricted
Default-value use is time-limited and capped rather than open-ended, so a clear evidence trail matters.
- CBAM reporting has required actual, not estimated, data since 1 August 2024; default values could substitute only until 31 July 2024.
- No adopted rule bans default values outright after a fixed date; the escalating mark-up is what makes verified actual data progressively cheaper.
- A limited tolerance still allows up to 20 per cent of a complex good’s embedded emissions to rest on default or estimated values.
- Supporting records behind the calculation must be kept for four years.
Across GreenSutra’s CBAM work, exporters frequently find their installation already logs much of the source-level data an actual calculation needs, though rarely in the structure a verifier expects. A short CBAM discovery call maps the gap between existing meters and a declaration an accredited verifier can approve.
Sources: Regulation (EU) 2023/956 · Implementing Regulation (EU) 2025/2621 · European Commission CBAM