UK lays the CBAM Emissions and Verification Regulations: the January 2027 rulebook takes shape

The last major piece of UK CBAM secondary legislation is now law. The Carbon Border Adjustment Mechanism (Emissions and Verification) Regulations 2026 (SI 2026/995) were made on September 8, 2026, laid before the House of Commons on September 9, and come into force on January 1, 2027, the same day the UK CBAM itself takes effect. The instrument runs to 17 regulations across five parts and sets how embodied emissions in imported aluminium, cement, fertilizers, hydrogen, and iron and steel are calculated, monitored, verified, and recorded.

This closes the gap our earlier coverage flagged: as recently as the first week of September, the Emissions and Verification Regulations were still a consultation draft, the only major instrument not yet made. That status is now superseded. Importers know how their rate will be set, and as of September 9 they also know the legal rules for measuring the tonnes.

What SI 2026/995 contains

SI 2026/995 sets the emissions determination and verification framework for the UK CBAM: how embodied emissions are calculated under default values or actual data, who may verify actual emissions data, what a verification report must contain, and how long records must be kept. The Treasury made regulations 1 to 5 and 7 under sections 148(2) and 157(1) and (2) of the Finance Act 2026; HMRC Commissioners made regulations 1, 2 and 6 to 17 under sections 154(4) and 157(1) and (2) of, and paragraphs 7(3), 10, 13 and 14 of Schedule 17 to, the same Act, with regulations 1, 2 and 7 made by both. The five parts divide as follows.

• Part 1: preliminary matters, including citation, commencement, and definitions
• Part 2: calculating embodied emissions, covering both default values and actual emissions
• Part 3: monitoring and verification of emissions data, including verifier and accreditation requirements
• Part 4: record keeping
• Part 5: amendments to the Administrative Provisions Regulations (SI 2026/802)

Regulation 2 anchors the technical scope in the "Carbon Border Adjustment Mechanism: System Boundaries Document", version 1.00 dated 10th July 2026, the HMRC document that defines which production processes and emissions count. What HMRC published as a supporting reference document on July 10 now carries a statutory reference.

Default values or verified actual emissions: the choice every importer faces

Part 2 gives every registered importer two routes to an emissions figure: multiply the weight of the good by a Treasury default value, or calculate verified actual emissions under an eight-step methodology. Regulation 4 sets the default route: embodied emissions equal the weight of the good multiplied by the default value, with the default values themselves to be specified in Treasury notices under paragraph 11(1) of Schedule 17 to the Finance Act 2026. Those notices have not been published yet, which makes them the single most important number still missing from the UK regime.

Regulation 5 sets the actual emissions route. The methodology takes verified emissions data from the monitoring period, converts non-CO2 greenhouse gases into CO2 equivalents, adds emissions embodied in precursor goods, and divides by the production weight to derive an emissions intensity per tonne. That intensity, multiplied by import weight and by the quarterly UK CBAM rate, determines the bill for importers who go beyond defaults. Producers with cleaner-than-average processes gain from the actual route only if their data survives verification.

Who can verify emissions data under the UK regime

Only an independent, accredited verifier can sign off actual emissions data, and regulation 15(1) requires the accrediting body to be a full member of the Global Accreditation Cooperation Incorporated. Regulation 12(1) sets three conditions: the verifier must be independent of the importer, the production installation and its operator, and any precursor good installation and operator; accredited by a qualifying accreditation body; and compliant with any additional standards the Commissioners specify in published notices. Regulation 14(2) prescribes the verification report contents, including installation and operator details, the verifier's accreditation number, the monitoring period, and "a verification opinion statement" on whether the operator's emissions data are sufficiently accurate to count as verified.

Two housekeeping parts complete the instrument. Regulation 16(3) requires the verification report or good-specific verification summary to be "kept for a period of 6 years, beginning with the day after the accounting period to which the records relate". Regulation 17 amends the Administrative Provisions Regulations (SI 2026/802) by adding three items to the content of CBAM returns: whether section 147(2) of the Finance Act 2026 applies to the good, the level of any default value used, and, where actual emissions data are used, the emissions intensity, which must be verified by a verifier.

The UK CBAM legislative stack, September 2026

With SI 2026/995 made, all four major statutory instruments under the Finance Act 2026 are law, and the UK CBAM legislative framework is substantially complete. The table below shows the full stack and how our July assessment has changed.

When the July package landed, we reported that SI 2026/809 fixed the rate formula and carbon price relief while the Emissions and Verification Regulations remained the one major outstanding piece. That piece landed roughly eight weeks later, comfortably inside the "later in 2026" window the government had indicated. All four instruments come into force on January 1, 2027.

What remains outstanding before January 1, 2027

Substantially complete is not complete: four operational items still stand between the made regulations and a functioning regime. The remaining milestones are listed below.

1. Treasury default value notices under Schedule 17, paragraph 11(1), the actual numbers behind regulation 4
2. The opening of UK CBAM registration through HMRC's Government Gateway, expected in the final quarter of 2026 against the £50,000 threshold
3. An illustrative rate example from HMRC, expected in autumn 2026
4. The first published quarterly sector rates, due at the start of January 2027 once fourth-quarter 2026 UK ETS auction data is in

For importers, the practical consequence of SI 2026/995 is a supplier data decision that can no longer wait. The first accounting period covers calendar year 2027 with the return due May 31, 2028, and an importer who wants to use actual emissions for 2027 needs monitoring and verification arrangements in place at its suppliers' installations from day one; verification cannot be reconstructed after the fact. Importers who will rely on defaults instead should watch for the Treasury notices, since those values determine whether the default route is a convenience or a surcharge. The preparation sequence from threshold monitoring to first return is set out in the UK CBAM compliance guide, and the structural contrast with the EU's certificate-based system in the UK CBAM vs EU CBAM comparison.