UK CBAM 2027 — A Complete Guide for Polish Exporters to the United Kingdom

From 1 January 2027, the United Kingdom is launching its own carbon border adjustment mechanism — the UK Carbon Border Adjustment Mechanism (CBAM). The registration, reporting and payment obligations fall on the importer of CBAM goods into the UK. For Polish companies exporting aluminium, steel, cement, fertilisers or hydrogen, this mainly means supplying emissions data to UK customers – and direct obligations only where the Polish company acts as the importer. This article explains what UK CBAM is, who it applies to, how the charge is calculated, and how to prepare — step by step.

What UK CBAM is and why it exists

UK CBAM (Carbon Border Adjustment Mechanism) is a charge on the embedded CO₂ emissions in specified goods imported into the United Kingdom. Its purpose is to level the playing field between domestic producers, who pay for their emissions under the UK Emissions Trading Scheme (UK ETS), and importers from countries with lower or zero carbon costs.

Without CBAM, cheap imports from regions with less strict climate policy could push UK producers — who bear the cost of emissions allowances — out of the market, a phenomenon known as carbon leakage. CBAM applies an equivalent charge to imported goods, removing this asymmetry.

Important: UK CBAM is a separate system from the EU CBAM. The liable person under UK CBAM is the importer of CBAM goods into the UK – where customs duties apply, this is the person named on the import declaration, even if a customs agent or freight forwarder declares the goods on their behalf; the importer may be established in the UK or outside the UK (gov.uk). A Polish exporter is therefore directly liable for UK CBAM only if it is itself the importer (e.g. when delivering on DDP terms). If you import CBAM goods into Poland (or another EU country) from the UK or other third countries, EU CBAM applies to you — these are two distinct regimes with different deadlines and procedures (see CBAM from 1 January 2026 and imports from the UK to Poland).

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UK CBAM vs EU CBAM — the key differences

Criterion	UK CBAM	EU CBAM
Administering authority	HMRC (United Kingdom)	European Commission / KAS
Definitive regime starts	1 January 2027	1 January 2026
Registration threshold	£50,000 import value / year	50 tonnes net mass / year (per importer; Regulation (EU) 2025/2083)
First accounting period	1 Jan 2027 – 31 Dec 2027	1 Jan 2026 – 31 Dec 2026
First declaration deadline	31 May 2028	30 September 2027
Charging mechanism	CBAM rate × embedded emissions	Purchase of CBAM certificates
Relief for carbon price paid abroad	Yes (Carbon Price Relief)	Yes (carbon price deduction)

Note for Polish companies: if you both export to the UK and import from the UK into Poland, you may be subject to both systems independently. Check both thresholds and both sets of deadlines.

Which goods are covered by UK CBAM?

UK CBAM covers goods from five sectors considered exposed to carbon leakage. Scope is set at the level of CN/tariff codes:

Sector	Example goods
Aluminium	Rolled products, bars, profiles (excluding scrap — outside scope)
Cement	Cement clinker, Portland cement and related products
Fertilisers	Nitrogen fertilisers, ammonia, urea
Hydrogen	Gaseous and liquefied hydrogen
Iron and steel	Hot- and cold-rolled products, pipes, profiles (excluding scrap)

Excluded from scope (from 2027): aluminium scrap and iron/steel scrap — identified by CN code.

Planned extensions: glass and ceramics have been flagged as sectors for future review, but are not within the scope of UK CBAM from 2027. Indirect emissions (electricity) are only expected to be covered from 2029 at the earliest (announced, but the date is not yet fixed in law).

Who has to register with HMRC?

The registration obligation falls on the importer of CBAM goods into the United Kingdom. The registration threshold is £50,000 of CBAM goods import value within a year.

HMRC applies two tests — both need to be monitored on an ongoing basis:

1. Forward-looking test: will the value of CBAM goods imported over the next 30 days exceed £50,000? If so — registration is mandatory.
2. Backward-looking test (on the first day of each month): did the value of CBAM goods imported over the past 12 months exceed £50,000? If so — registration is mandatory.

Source: HMRC, gov.uk. CBAM goods imported before 1 January 2027 do not count towards the threshold.

How is the CBAM charge calculated?

The CBAM charge is the product of the emissions embedded in the imported goods and the CBAM rate in force at the time of import.

The CBAM rate is set and published by the government every quarter (from 1 January 2027) and reflects the price of allowances under the UK ETS — so that the cost to the importer matches the cost borne by domestic producers.

Simplified calculation:

CBAM charge = Embodied emissions [tCO₂] × CBAM rate [£/tCO₂]
CBAM liability = CBAM charge − Carbon Price Relief (where applicable)

The CBAM rate is set separately for each sector based on the average UK ETS allowance price in the relevant quarter, adjusted for free allocation (the free allocation adjustment). From 2027 UK CBAM covers only direct emissions (including those embodied in precursors); indirect emissions are to be included in 2029 at the earliest. Source: CBAM: Policy summary, gov.uk.

Carbon Price Relief (CPR): if, in the country of export, the producer paid for its emissions (e.g. under the EU ETS or another scheme), the importer may claim a deduction of that amount from the CBAM charge. This requires documenting the effective carbon price paid abroad.

HMRC has published illustrative rates and a worked example; the applicable rates will be published from 1 January 2027 at the beginning of each quarter (gov.uk).

UK CBAM obligations calendar — what and when

Date	Obligation
Before 1 Jan 2027	Check whether you import CBAM goods and whether you exceed the £50,000 threshold
1 January 2027	Start of the first UK CBAM accounting period
Ongoing throughout 2027	Monitoring import value (the 30-day and monthly tests)
Ongoing throughout 2027	Gathering embedded emissions data from suppliers
31 December 2027	End of the first accounting period
31 May 2028	Filing the first CBAM declaration and paying the charge to HMRC

How to prepare your company — 5 steps

Step 1: Identify CBAM goods in your portfolio

Review the CN codes of the goods you trade and check whether they fall within the scope of aluminium, cement, fertilisers, hydrogen or iron/steel. HMRC has published the list of commodity codes in scope of CBAM on gov.uk (practical guidance for the steel and aluminium sector: UK CBAM 2027 for steel and aluminium exporters): Check which goods are in scope of CBAM.

Step 2: Assess your import value

Work out whether the annual value of your CBAM goods imports exceeds, or might exceed, £50,000. Factor in any planned increase in orders.

Step 3: Register with HMRC

Registration is done with HMRC. The detailed registration procedure will be made available before 1 January 2027. Make sure you hold an active GB EORI number (see how to get a GB EORI) — it's required for any customs declarations to the UK.

Step 4: Gather emissions data from suppliers

UK CBAM requires reporting the embedded emissions in imported goods. Contact your non-UK suppliers and ask for data on the carbon footprint of production (direct embodied emissions). Plan this process well ahead of time — gathering the data can take a while.

Step 5: Plan your Carbon Price Relief documentation

If your supplier operates in a country where emissions are taxed (e.g. under the EU ETS), you may be able to claim CPR. Gather evidence confirming the effective carbon price paid in the country of production.

How we can help

Agencja Celna at agencjacelna.uk specialises in customs clearance on the Poland–UK route. We support importers and exporters with:

• checking whether your goods fall under UK CBAM and EU CBAM,
• GB EORI registration and HMRC procedures,
• tariff classification (CN codes) for CBAM goods,
• preparing Carbon Price Relief documentation,
• ongoing monitoring of changes to UK and EU regulations.

Get in touch with us: contact form — we'll advise you on which obligations apply to your company before UK CBAM starts in 2027.

Sources

• Factsheet: Carbon Border Adjustment Mechanism — GOV.UK
• Carbon Border Adjustment Mechanism — GOV.UK
• CBAM: Policy Summary — GOV.UK
• EU Carbon Border Adjustment Mechanism — business.gov.uk

Frequently asked questions