The 2026 edition of “ZeroedIn: The Brand Marketing Pulse” is now live.
The 2026 edition of “ZeroedIn: The Brand Marketing Pulse” is now live.
Real Supplier Data Requirement: Verified, plant-level carbon accounting is now a UK statutory law so general supply-chain emissions data can be costly.
Defaults Allowed – But You Pay More: Failing to secure accredited supplier data forces shipments onto expensive Treasury default rates, stripping away clean production allowances and shrinking import margins.
2027 is a Transitory Year – But Capture the Data: While the first formal tax return isn’t due until May 2028, the legislation strictly demands actual 2027 calendar-year data. Delaying supplier audits now guarantees penal rates later.
Multi-Tier Precursor Liability: Importers can no longer just audit their direct vendors – Tier-2 supplier data are required to calculate final emissions intensity.
The UK’s Carbon Border Adjustment Mechanism (CBAM) starts on 1 January 2027. It places a carbon price on the emissions embodied in imported aluminium, cement, fertiliser, hydrogen, and iron and steel, so that imports face a carbon price comparable to the one UK manufacturers already pay.
9th September Update: The policy framework has been in place since the Finance Act 2026. What was missing was the detail of how emissions are calculated and who’s allowed to verify them. This was finalised on 9 September 2026, with the CBAM Emissions and Verification Regulations. HMRC updated its CBAM policy summary the same day.
The question of data: An importer’s bill depends on emissions measured at the installation that made the goods, verified by an accredited third party, and that data has to have been generated during 2027.
There are two ways to report the emissions embodied in a CBAM good:
Defaults exist so that businesses can still meet their obligations when actual data isn’t available, and for some consignments they’ll be the sensible choice.
However, there are restrictions: Actual emissions data can’t be used for precursor goods if a default value is used for the final good, so the choice applies to the product as a whole rather than to the parts that happen to be easy to evidence. Any producer whose emissions are better than the default has a commercial reason to get verified data to its UK customers, and any importer buying from one has a reason to ask for it.
As we don’t know exactly when the default values will be available, it’s worth starting the modelling work now with whatever data you already have.
Verifier rules: The installation appoints an independent verifier (accredited against ISO/IEC 17029:2019 and ISO 14065:2020) and accredited for the right scope of activity: a verifier approved for urea and mixed fertilisers isn’t automatically eligible to verify an iron and steel installation.
Site visits: The verifier must also make a physical site visit at one or more appropriate points during the monitoring period, with exceptions set out in the emissions and verification force of law notice. The site visit therefore has to fall inside the year being reported, which means a verifier signing off 2027 data needs to be appointed and on site during 2027.
Which year’s data: There’s some flexibility on which year’s data can be used. For goods imported in 2027, the importer should use the most recently verified emissions intensity available from 2027 or, where no verified 2027 data exists, from 2026.
Crossover with EU CBAM: The monitoring and verification methodologies have been designed to be broadly interoperable with the EU CBAM, so a supplier already being verified for that scheme can use the same verification documentation in many cases.
Precursors. A complex good carries the emissions of the precursor goods used to make it, such as clinker in cement. Checking your direct supplier is only enough where that product has no in-scope precursors behind it, and the System Boundaries Document is what settles that question.
Weight. Liability is calculated on the net weight of the good in kilogrammes, excluding packing materials and packing containers of any kind. If the correct weight isn’t provided, or the supporting records are not kept, HMRC can determine the weight itself.
Non-CO2 gases. Emissions are converted using set factors of:
The biggest impacts will be on aluminium smelting and nitric acid and nitrogenous fertiliser production.
Carbon price relief. A carbon price already paid overseas reduces the UK liability, but only with a completed carbon pricing verification form, a publicly available headline price for the scheme, and any compensation or rebates the installation received deducted from the calculation. There are currently no jurisdictions exempt from UK CBAM and no international arrangements in place.
1. Start with the commodity codes in the annex to the policy summary and check them against what you’re importing, and then apply the two registration tests against the £50,000 threshold:
2. Identify the installation behind each product, including precursors, and put data provision into supply contracts so that verified emissions intensity and carbon pricing evidence arrive after the calendar year closes without a negotiation each time.
3. Then when the defaults are available, compare what using those would cost you compared with any verified data you’ve managed to get, supplier by supplier, and set up record keeping to be kept for 6 years, including the evidence behind the net weight you declare.
Your UK customers will be asking for installation-level emissions intensity, verified, for a calendar year monitoring period. Appointing an eligible verifier early enough for the site visit to fall inside the monitoring period is the step with the stricter deadline attached to it. Alongside that, align monitoring with the System Boundaries Document and the force of law notice, and be ready to issue a good-specific verification summary, which the regulations allow you to send instead of the full verification report where you’d rather not share everything in it.
If your installation sits in a jurisdiction with its own carbon price, collect that evidence too, including any rebates or compensation received, because your customer can’t claim relief without it. A supplier who can hand over a clean verification report and a completed carbon pricing verification form is a materially cheaper supplier to buy from in 2027, so complying early and thoroughly increases your potential market share.
| Date | What happens |
|---|---|
| Autumn 2026 | HMRC publishes an illustrative CBAM rate |
| 1 January 2027 | CBAM applies to specified goods imported on or after this date; rates published quarterly |
| 31 January 2028 | Registration deadline for the first calendar year (otherwise 30 days from becoming liable) |
| 31 May 2028 | First return and payment, covering the accounting period 1 January to 31 December 2027 |
| From 1 January 2028 | Accounting periods move to a quarterly cycle |
| 6 years | How long CBAM records must be kept after the end of the accounting period |
CBAM turns supplier emissions data into a line on a tax return. At 51toCarbonZero, that’s the work we do: our platform holds over 40,000 emission factors and a supplier intelligence database covering 1.5 million suppliers, with more than 3,000 pre-built integrations to pull data from the systems you already run, and we hold a 100% audit pass rate across our clients.
For importers, we can map products and precursors against scope, help you run the supplier engagement to collect installation-level data, and model default values against verified data so you can see which are better from a cost perspective.
For overseas producers selling into the UK, we can prepare installations for verification and put the monitoring in place before the 2027 monitoring period opens.
Through Climate Unlimited™, all of this comes with a named Climate Success Manager rather than an hourly rate and a new scope every time your requirements change. If you import into the UK, or supply someone who does, we can help you work out where you stand and get you the calculations you need before the rules kick in.
Sustainability Made Simple.