How big an error fails a UK CBAM verification?
An error is material once it moves your product's emissions intensity by more than 5%. HMRC's UK CBAM guidance sets that level, and the verifier can only sign your data off as satisfactory when no uncorrected material misstatement is left. Several small errors that add up past 5% count too.
What the 5% applies to
The materiality level is 5% of the total emissions intensity of each CBAM good, in tonnes of CO2e per tonne. It is not 5% of the whole plant's emissions, so a small product line with a bad number can fail on its own.
When smaller errors still count
- Errors that are each below 5% but add up past it are treated as material.
- The verifier also uses judgement where an error badly distorts another figure, such as a fuel total, without moving the intensity much.
- Misstatements include typing errors, meter errors and calculation errors.
What the verifier does with an error
The verifier raises each misstatement with you and gives you the chance to correct it. Only data free of uncorrected material misstatements can be verified as satisfactory, and the verifier must reach that view with reasonable assurance.
Worked example: one wrong furnace oil entry
- Verified intensity of hot-rolled bars: 2.400 tCO2e per tonne.
- 5% of 2.400 = 0.120 tCO2e per tonne. That is the material line.
- A missed furnace oil invoice adds 0.090 tCO2e per tonne: 3.75%, not material on its own.
- A weighbridge error adds another 0.045: total 0.135, or 5.6%. Together they are material and must be corrected.
What Senseible does here
Senseible links each figure to the invoice or bill it came from, so a verifier can trace a fuel total back to the documents and you can fix a slip before it grows. 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.
Sources: HMRC, UK CBAM monitoring, reporting and verification technical guidance (October 2026), HMRC, Carbon Border Adjustment Mechanism (CBAM): Policy summary (updated 2 November 2026)
Last reviewed 2026-11-02.