UK CBAM key dates: register by 31 January 2028, first return 31 May 2028

The timeline, in order

Charging starts on day one: no report-only phase

This is the sharpest difference from the EU scheme. The EU ran a transitional period where importers only had to report embedded emissions before any charge applied. The UK has no such phase: from 1 January 2027 the charge is live. Practically, that means the emissions and values you record during 2027 feed directly into a bill, so the data discipline has to be in place before the period opens, not bolted on later.

Registration: 30 days, eased to 31 January 2028 in year one

The ordinary rule is that a liable person has 30 days to register with HMRC from the day they become liable. Recognising that the first year is a standing start, there is an easement: during the first calendar year of CBAM, businesses have until 31 January 2028 to register. If you become liable early in 2027, the easement gives you breathing room; if you become liable later, the ordinary 30-day rule may bite sooner. Work out which applies to you rather than assuming the January 2028 date covers every case.

The first return: 31 May 2028, covering all of 2027

The first accounting period is annual, running 1 January to 31 December 2027, and the first return and payment are due 31 May 2028, five months after the period closes. That single return covers your whole first year of CBAM imports. After that, the rhythm changes.

Quarterly from 2028

From 2028 onwards, accounting periods become quarterly, with returns and payments due after each quarter on staggered deadlines. The exact 2028 quarter dates are being finalised in secondary legislation, so we do not state them as fixed here; our status board tracks them as a live item and we update the date table when the regulations are laid.

Get your dates personalised

The free scope check shows these dates the moment it puts you in or near scope. The paid report renders them as a dated countdown checklist tied to today, alongside your in-scope answer and an estimated cost.

Frequently asked questions

Sources

• GOV.UK, Introduction of the Carbon Border Adjustment Mechanism, on the 1 January 2027 start and the first annual accounting period. gov.uk
• GOV.UK, CBAM Policy Summary, on the 30-day registration rule, the 31 January 2028 easement, the 31 May 2028 first return, and the move to quarterly periods. gov.uk

Content current as of 12 July 2026. The 2028 quarterly deadlines are being finalised in secondary legislation; we update this page when they are laid. Re-check the primary source before acting on anything time-sensitive.