A meter failed for a month. What does the UK CBAM expect?

Fill the gap with a conservative estimate and record how you did it. HMRC's UK CBAM guidance suggests, for example, the average flow rate for the same period plus a supplement such as one standard deviation. The method must be written in your monitoring plan before the gap happens.

Conservative means

The substitute must not understate emissions or overstate production. When in doubt, the estimate leans towards more emissions.

HMRC's examples

• Missing lab analysis of a fuel: use a standard value.
• An unweighed delivery truck: use the average of similar loads in the same period plus a supplement, for example one standard deviation.
• A failed flow meter: use the average flow rate for the period plus a supplement, or estimate conservatively if no other instrument exists.
• Missing heat measurement: estimate from the process efficiency over the period, plus a supplement.
• A meter reading with higher uncertainty can still be used while it is repaired, as it gives a conservative value.

What to do now

1. Write your gap-filling methods into the monitoring plan.
2. Keep purchase invoices: they are an independent check on what the meter should have read.
3. Repair or replace the instrument as soon as possible, and review the methods regularly.

Worked example: gas flow meter down for 30 days

• Daily gas use over the other 335 days: average 4,200 SCM, standard deviation 350 SCM.
• Substitute per day: 4,200 + 350 = 4,550 SCM.
• Gap total: 4,550 x 30 = 136,500 SCM, against 126,000 SCM at the plain average.
• The extra 10,500 SCM keeps the estimate conservative.

What Senseible does here

Senseible reads monthly fuel and power invoices, which give an independent total to compare against a failed meter. 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.

• How to fill data gaps
• CBAM Suite

Sources: HMRC, UK CBAM monitoring, reporting and verification technical guidance (October 2026)

Last reviewed 2026-11-02.