Up to four record sets have to exist before verification begins. They are monitoring methodology documentation and installation activity data. Precursor purchase records, carrying the supplier’s verification report, are needed for complex goods. Electricity consumption with emission factor evidence is needed where indirect emissions count (cement and fertilisers). The installation keeps the records behind the embedded emissions calculation for at least six years after the reporting period, under Implementing Regulation (EU) 2025/2547. CBAM Monitoring Plan in 2026 sets out what those records must cover.
A verifier examines whether a declared figure can be traced, reproduced and defended. Assembling that trail after the monitoring year has closed is usually impossible, because the underlying operational records were either never created or have already been overwritten.
The four record sets
| Record set | What it must contain |
|---|---|
| Monitoring methodology | The documented approach used, whether calculation-based including mass balance, or measurement-based using continuous emission monitoring |
| Installation activity data | Production volumes, fuel and material inputs, and process data at installation level rather than company level |
| Precursor records | Purchase records for relevant precursors, carrying each supplier’s verification report for the reporting period, or a note that a default value is used |
| Electricity | Consumption data and the emission factor applied, with evidence for the factor chosen, where indirect emissions count (cement and fertilisers) |
Why the methodology has to be documented in advance
Direct emissions are monitored using either a calculation-based approach, which includes a mass balance method, or a measurement-based approach using continuous emission monitoring. Which was used is not a presentational choice made at reporting time. A verifier tests whether the stated method was actually the method applied throughout the period, so the documentation has to predate the data it governs.
The precursor chain is the usual failure point
A complex good aggregates the production process and the embedded emissions of the precursors used to make it. That means a supplier who will not or cannot report its own embedded emissions leaves a gap the exporter cannot close internally. Article 15 of Implementing Regulation (EU) 2025/2547 allows a default value for that precursor, so the gap can be filled, though with a country figure rather than the supplier’s own.
Where actual data is not used, country-of-origin default values apply. Their mark-up is 10 percent in 2026, 20 percent in 2027 and 30 percent from 2028, and a flat 1 percent for fertilisers. Verified actual data is therefore in most cases the cheaper route.
Sources: Regulation (EU) 2023/956, Implementing Regulation (EU) 2025/2547
Getting supplier emissions data out of a precursor chain is the longest lead item in any CBAM programme. CBAM solutions covers supplier data collection and monitoring documentation, and the CBAM guide sets out the calculation methodology those records support.