CBAM timeline

1 January 2027

CBAM starts

All in-scope imports from this date incur the levy. The first accounting period runs the full 2027 calendar year.

31 January 2028

Registration deadline

Importers who met the £50,000 threshold during 2027 must register with HMRC by this date.

31 May 2028

First return and payment

The return and payment for the 2027 accounting period are due, at a rate set per sector, per quarter, derived from the UK ETS price adjusted for free allocation.

2028 onwards

Quarterly accounting periods

Q1 2028 is due 31 July 2028, Q2 2028 is due 29 September 2028, and thereafter returns are due on the last working day of the second month after each quarter ends. Records must be kept for 6 years.