# When does a UK importer file CBAM returns after 2027?

Canonical: https://senseible.earth/answers/uk-cbam-returns-after-first-year

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.

- [CBAM for Indian exporters](https://senseible.earth/cbam)
- [Mixing defaults and actual data](https://senseible.earth/answers/uk-cbam-default-values-mixing-rules)

Sources: [HMRC, Carbon Border Adjustment Mechanism (CBAM): Policy summary (updated 2 November 2026)](https://www.gov.uk/government/publications/carbon-border-adjustment-mechanism-cbam-policy-summary/carbon-border-adjustment-mechanism-cbam-policy-summary)

Last reviewed 2026-11-02.