HMRC has issued another set of draft regulations and technical notices for the calculation of emissions. For its start in 2027, the UK is currently translating its CBAM framework into detailed secondary legislation. Statutory instruments and notices with force of law establish the practical foundations for implementation. 

 (Last update on 13/04/2026)

Secondary legislation is setting the rules

The UK Carbon Border Adjustment Mechanism (CBAM) has progressed from principles to detailed rule‑drafting. CBAM itself enters into force on 1 January 2027 – one year later than the EU CBAM.

Primary legislation was introduced in the Finance Bill 2025–26 from March 18, 2026. These core rules will be operationalized through secondary regulations and notices, which are currently worked out. Final regulations are expected to be laid later this year.

On 10 February 2026, HM Revenue & Customs (HMRC), the UK’s tax authority,  opened a technical consultation on the first tranche of draft secondary legislation covering administration, CBAM rate and carbon price relief calculations and transitory provisions. The feedback period ended on 24 March 2026.

A second tranche with focus on emissions followed on April 9. These regulations set the rules for the calculation of embodied emissions and its monitoring and verification. Consultations are running until May 21.

Together these regulations set a carbon price on embodied emissions in imports of specified, carbon‑intensive goods – comparable to that borne by UK producers in the UK Emissions Trading System (ETS). The objective is to reduce carbon leakage while supporting the UK’s decarbonisation pathway.

Detailed rules for implementation

For now, 5 secondary legislations build the CBAM implementation framework. These statutory instruments set the rules for implementation from 2027 onwards. Its application is detailed in Notices with force of law. HMRC’s Policy Summary offers a living overview.

Administrative provisions

This SI defines the administrative requirements for CBAM:

1. process to register, and the content and timing of CBAM returns;
2. rules on reimbursement;
3. the treatment of weight;
4. and record‑keeping obligations.

It explains the information HMRC expects from importers, the accounting periods (quarterly), and the evidential standards businesses must meet to support their filings. For importers of CBAM goods, this is the regulation set concrete compliance requirements.

CBAM rate and carbon price relief

This SI sets out the technical rules for the pricing of emissions based on:

1. calculation of the CBAM rate for each sector;
2. claiming Carbon Price Relief (CPR) where overseas carbon prices (e.g., an ETS price or a carbon tax) have already been paid with conditions, and rules for verification, calculation, currency conversion and record keeping.urrency conversion for CPR.

This is the technical underpinning for the CBAM tax to be paid. This SI explains the inputs HMRC uses to set sectoral CBAM rates and the evidence to be provided to reduce liability where a qualifying carbon price applied before import. This SI defines the rate‑setting approach and the principles underpinning CPRs.

CBAM emissions and verification

This SI outlines the rules for determining embodied emissions based on default or actual values covering:

1. calculation of embodied emissions;
2. monitoring and verification of emissions data;
3. record keeping.

They form the rules for the emissions calculation by UK importers. They also define the monitoring and verification requirements for non-UK manufacturers as operators of installations with actual data for emissions. With this they set requirements to become an accredited CAM verifier and for accreditation bodies.

CBAM system boundaries

This SI sets the boundaries for the calculation of embodied emissions with:

1. mapping of commodity codes aggregated goods categories;
2. definition of system boundaries across-sectors and for each CBAM sector.

This regulation define which production activities and which emissions are in scope of CBAM and hence are to be monitored and priced according to the other set of regulations.

Transitory provision

For a phasing in of CBAM in the first year, this SI defines the diverging dates and timing related to registration, payment and accounting periods for 2027.

These provisions define the internal timetables, cash flow and governance during the inaugural year for importers of CBAM goods before the regular quarterly rhythm resumes. These transitional adjustments are supposed to make CBAM workable from day one.

Notices with force of law

Alongside the SIs, HMRC has published draft notices with force of law. These will sit next to the regulations and offer more practical instructions for implementation.

The notices on administrative requirements describe what importing companies need to submit and how, and what will constitute acceptable evidence. They are essential reading for building the internal processes and data flows for 2027.

The notices on emissions determination detail the monitoring requirements for non-UK operators, the requirements for verifiers and accreditation bodies. They form the technical rule book for the provision of actual data by non-UK manufacturers and accredited UK verifiers.

How to get prepared for 2027

These secondary legislations set the practical CBAM foundation: who registers, what returns must contain, how CBAM rates and CPR are determined, how emissions are calculated and verified, and how the first‑year timetable will work.  

To get ready for 2027, UK companies should take key steps:

• Map scope & triggers: Track purchases and imports based on the covered commodity codes and assess when the £50,000 (rolling) threshold will trigger registration.
• Design quarterly compliance: Set up processes and schedules for quarterly returns and align cut‑offs with the transitional timing.
• Build data & controls: Configure systems to capture return content, weight, embodied emissions and required records.

With consultations ongoing, the final regulations will only be finalized later in 2026. For reliable CBAM cost calculations, further details (e.g. default values and CBAM rates) are needed too. Importing companies need to keep their implementation plans “living” and anchored in any updates.

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Sources and further information:

• HM Revenue & Customs: CBAM Draft Legislation (Administration & CBAM Rate)
• HM Revenue & Customs: CBAM Draft Regulations (Emissions & Verification)
• HM Revenue & Customs: CBAM Policy Summary

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