Liable persons will need to complete and submit an online tax return following the end of each accounting period. The return will need to cover the whole accounting period and, subject to the proposed deregistration requirements, nil returns would be required where a registrable person has not imported any CBAM goods during the relevant accounting period.

The content required on a return was likely to include:

• The CBAM commodities imported by reference to the commodity codes,
• The dates of import
• The weight of CBAM goods
• The total emissions embodied (or default value)
• Any effective overseas carbon prices incurred.

The first accounting period would be 12 months and that returns and payments would be due five months after the end of the first accounting period (31 May 2028). From 1 January 2028, the UK proposed that accounting periods would be quarterly and to gradually transition to returns and payments due a month later, to align with how other taxes are generally administered by HMRC.

(Note: The government will continue to consider the approach to accounting and payment periods from 2028 alongside the requirements for measuring and verifying emissions, calculating and verifying the overseas carbon price, and the information required on a return.)

Source: GOV.UK

• Why is the UK introducing Carbon Border Adjustment Mechanism (CBAM)?
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