A CBAM charge will apply to specified goods in the aluminium, cement, fertiliser, hydrogen, and iron and steel sectors imported into the UK on or after 1 January 2027. The charge is payable by the importer. The importer must register with HMRC for CBAM if, after applying forward-looking and backward-looking tests, they meet or exceed the minimum registration threshold of £50,000. 

The first accounting period for CBAM will begin on 1 January 2027 and end on 31 December 2027. The deadline for filing the return for the first accounting period, and paying any CBAM due, will be 31 May 2028. 

An earlier article explains in more detail how CBAM is expected to work. 

Legislative process

Legislation included in the Finance Bill 2025-26 provides the core framework for CBAM. Secondary legislation will provide for the operation of CBAM. The government has published the first batch of draft secondary legislation for consultation, which comprises of three sets of regulations and a notice that will have the force of law . 

Areas covered by the regulations and notice include:

• registration for CBAM;
• tax returns and required content;
• reimbursement arrangements;
• weight of CBAM goods; and
• record keeping.

The government is seeking “feedback from stakeholders on the drafting of the draft secondary legislation to ensure that it delivers the policy correctly and effectively for the tax to operate as intended and provide for administrative matters”. The consultation closes on 24 March 2026. 

A second set of draft secondary legislation will be published in spring 2026 for technical consultation.

Further information

• Carbon Border Adjustment Mechanism - GOV.UK
• Carbon border adjustment mechanism (CBAM): Policy Summary - GOV.UK