The UK CBAM rulebook is complete: emissions and verification regulations laid
On 9 Septemberthe government laid the Carbon Border Adjustment Mechanism (Emissions andVerification) Regulations 2026, SI 2026/995, before the House of Commons, witheffect from 1 January 2027. This is the instrument importers have been waitingfor since the draft went out to consultation in the spring, and it completesthe UK CBAM's legal framework: administration (SI 2026/802), the rate andcarbon price relief (SI 2026/809), the transitional easements (SI 2026/830),and now the rules for measuring and verifying the emissions the tax is chargedon.
A companioninstrument laid the same day applies the Finance Act 2009 interest provisionsto UK CBAM late payments and repayments from 1 January 2027. That is a quietsignal worth hearing: HMRC will charge and pay interest on this tax exactly asit does on any other.
What the regulations cover
The instrumentsets out how embodied emissions in imported aluminium, cement, fertiliser,hydrogen, iron and steel goods must be calculated, monitored and evidenced. Thecalculation works from installation-level data on fuels and productionprocesses rather than company averages, and it reaches upstream: emissionsembodied in precursor inputs such as pig iron or ammonia count towards thetotal, so importers cannot stop their enquiries at the direct supplier [checkthe precise precursor provisions in the SI text before publication].
Where importerswant to use actual emissions figures rather than default values, those figuresmust be independently verified, and the verifier must hold accreditationrecognised under the UK rules [confirm the accreditation requirements in thefinal SI before publication]. A report from an unaccredited consultant will notdo. Importers without verified actual data fall back on default values set byHMRC, and the government has been consistent that defaults will beconservative.
The timing trap
Thetransitional easements soften the administrative deadlines: registration is notrequired until 31 January 2028 and the first return covers the whole of 2027[confirm both dates against SI 2026/830 and current HMRC guidance]. It would beeasy to read that as permission to deal with UK CBAM in 2028. It is theopposite. The tax accrues on imports from 1 January 2027, and the emissionsbehind those imports must be monitored as they happen. Installation fuelrecords and production data for March 2027 cannot be reconstructed in April2028, and a verifier asked to sign off numbers assembled after the fact willdecline. The businesses that treat 2027 as a live data year will file accuratefirst returns; the ones that wait will be filing on defaults.
What to do now
Check whetheryour imports of covered goods will carry you over the £50,000 registrationthreshold. Map your supply chain to installation level, including precursors,and send your overseas suppliers the system boundary documentation HMRC hasalready published. Ask intended verifiers about their accreditation status,because the EU experience suggests capacity will tighten. And put the choicebetween actual data and defaults in front of your finance team as a costeddecision, product by product.
The UK now hasa complete carbon border rulebook sixteen weeks before the tax starts. Theremaining work is not legal drafting; it sits in supply chains, meter recordsand monitoring plans.
CBAM-Assuredprovides UK CBAM training and MRV support for importers and their overseassuppliers; contact us to be ready for January.