When does a UK importer file CBAM returns after 2027?
The first UK CBAM return covers all of 2027 and is due by 31 May 2028. From 1 January 2028 returns become quarterly: January to March 2028 is due 31 July 2028, April to June by 29 September, July to September by 30 November, and October to December by 28 February 2029.
The return calendar
- 1 January to 31 December 2027: due 31 May 2028.
- 1 January to 31 March 2028: due 31 July 2028.
- 1 April to 30 June 2028: due 29 September 2028.
- 1 July to 30 September 2028: due 30 November 2028.
- 1 October to 31 December 2028: due 28 February 2029.
What this means for suppliers
Quarterly returns mean your buyer needs your verified figure more often and sooner. HMRC describes a gradual move to a two-month return window. A registered importer must file even when nothing is owed, for example when no CBAM goods came in that quarter.
Corrections
An importer can amend a return within 3 years of the end of its accounting period. That does not allow a return filed with default values to be switched to actual data later.
What Senseible does here
Senseible can total your records for any calendar quarter or year, so a figure is ready when the buyer's return is due. 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, Carbon Border Adjustment Mechanism (CBAM): Policy summary (updated 2 November 2026)
Last reviewed 2026-11-02.