CBAM Pulse
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HMRC publishes UK CBAM defaults, illustrative rates and MRV guidance

HMRC published UK CBAM default-values guidance, a draft default-values notice, illustrative rates and supplementary monitoring, reporting and verification guidance on 16 October 2026. The notices remain draft and have not commenced; the illustrative rates do not create or imply any tax liability and are not forecasts or the rates that will apply when liability begins. This technical package is separate from EU CBAM.

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What changed

  • Default-values guidance and the draft Default Values Force of Law Notice were published on 16 October 2026. HMRC's notice collection says the notices are drafts, have not commenced and do not currently have the force of law. Publication is not present legal effect.
  • HMRC also published illustrative rates and a worked example on 16 October. The official rates for imports from 1 January to 31 March 2027 are due before the end of 2026; the illustrations do not establish those rates. No numerical default table, illustrative rate or worked-example liability is reproduced here.
  • Supplementary MRV technical guidance was published on 16 October and remains subject to technical analysis and stakeholder feedback. Feedback can be sent to cbampolicyteam@hmrc.gov.uk on or before 13 November 2026, with 'MRV technical guidance feedback' in the subject line. This is a technical-feedback invitation, not an importer filing deadline.
  • UK CBAM commences on 1 January 2027. HMRC says registration will open on 1 January 2028; the later service opening is not a postponement of commencement.
  • HMRC's questions guidance was first published on 20 October and updated on 21 October. It directs general queries to an online form and detailed policy or technical queries to cbampolicyteam@hmrc.gov.uk. HMRC says it will review feedback and usually send a reply by email within 15 days: not a guarantee or a promise of 15 working days.
  • These UK publications do not change EU CBAM obligations or CBAM Pulse's EU calculator assumptions. Check the live HMRC documents for later changes and distinguish draft notices, supplementary guidance, illustrations and applicable official rates.

Who may be affected

Businesses preparing for UK CBAM, their suppliers, prospective UK verifiers and advisers following the separate UK regime. This briefing does not determine an individual importer's liability or registration position.

Official sources

Summary prepared by CBAM Pulse from the official sources linked above. It is informational only and not legal, tax, or customs advice. In case of any difference, the official text prevails.

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