As at 21 September 2026 the Treasury notice of default values under paragraph 11 of Schedule 17 to the Finance Act 2026 had not been published in any form, so the values, their structure and whether they vary by place of emission were not known. This page is revised on the day the notice appears.
What the law provides
Regulation 2 of SI 2026/995 defines a default value as the amount of carbon dioxide equivalent specified for a tonne of CBAM good or precursor good in a notice published by the Treasury under paragraph 11(1) of Schedule 17. Paragraph 11(3) provides that a default value may be set at a level that ensures there would be no advantage to any person liable to CBAM in using the value instead of determining the emissions under the regulations, and paragraph 11(4) explains that advantage includes the advantage of the emissions being lower if determined by default and the advantage of not bearing the cost of determining or verifying emissions.
What HMRC has said
HMRC's policy summary, which is guidance and not law, states that from 1 January 2027 there will be one default emissions value set per CBAM good and that the values will be published in a notice on gov.uk. If one value per good is carried into the notice, the Treasury will have chosen not to use the power in paragraph 11(2)(a) to vary the value by country of origin, at least at the outset.
What an importer should do now
An importer that cannot yet obtain verified data from its supplier will use the default value for the good, and an importer whose supplier has verified data will still meet the default value wherever a precursor's data is missing. Until the notice is published, an accrual for 2027 imports cannot be finalised, and the safe course is to hold the tonnage, the commodity code and the supplier for every consignment so that the calculation can be run on the day the values appear.