Written by Emmanuel Gianquitto, Head of Customs Consultancy and Training at ChamberCustoms
CBAM Enters Its Definitive Phase: What This Means for UK Exporters in 2026
The EU’s Carbon Border Adjustment Mechanism (CBAM) is entering its most commercially significant stage. From January 2026, CBAM moves from a transitional reporting regime into its definitive phase, where emissions data will directly drive financial charges on goods imported into the European Union.
For UK manufacturers, fabricators and exporters supplying EU customers, this marks a fundamental shift. Emissions data is no longer simply a compliance exercise for your EU importer – it is now a core commercial input that will influence pricing, competitiveness and supplier selection.
This update explains what is changing, what your EU customers will expect from you, and how UK businesses should be preparing.
The end of the transitional phase
By 31 January 2026, EU importers must submit their final transitional CBAM report for Q4 2025 (Oct–Dec). In practice, that means your EU customers will be asking you (their supplier) for robust emissions data to support their filing.
What is changing between Transitional Phase and Definitive Period?
From 1 January 2026, CBAM moves into the definitive period. The data collected for goods imported during 2026 will create a financial liability for EU importers. Put simply: CBAM becomes a real cost of importing your products into the EU, and that cost will increasingly influence commercial terms, pricing, and supplier selection.
Do I Need to Register in the EU?
As a UK supplier, you do not register as a CBAM declarant. The legal filing obligation sits with the EU importer (or their indirect customs representative, if applicable). Your responsibility is commercial: providing the information your customers need to comply, on time and in a verified format.
What About The 50-Tonne De Minimis Threshold?
CBAM includes a de minimis threshold of 50 tonnes per year per importer, for iron & steel, aluminium, cement and fertiliser. Electricity & Hydrogen are not subject to any threshold. This threshold applies to the EU importer, not the UK exporter.
If an EU importer brings in less than 50 tonnes in total of CBAM-covered products in a calendar year, CBAM obligations do not apply to that importer for that product.
If the threshold is exceeded, then CBAM tax is payable on the entire amount of CBAM goods imported, not just the increment over 50 tonnes.
While this exemption can be helpful for smaller importers, many EU customers are already planning on the basis that they will exceed the threshold and will therefore expect emissions data from suppliers as standard. However, UK exporters should be prepared with CBAM data to provide their EU Customers.
What Information Do I Need to Provide?
Expect tighter data requests. EU importers will want:
Embedded emissions data for the goods you supply (and the methodology behind it)
Supporting evidence where relevant (e.g., carbon price paid outside the EU)
Verification by an accredited independent verifier (often involving an onsite audit).
It is important that you ensure that you are collecting data consistently, since products you sold during 2026 may have been manufactured in previous years.
What Period Do I Need to Cover?
In the definitive period, EU reporting becomes annual. EU importers will have to file an annual CBAM declaration for 2026 imports by 30 September 2027. As a supplier, you may wish to align your data sharing to an annual cycle too.
How much CBAM levy will be due on my product at import?
EU importers will pay based on embedded emissions in the imported goods, adjusted through EU benchmark logic and phase-in mechanisms. Early years are expected to be moderated to support gradual implementation, and carbon pricing paid abroad may be deductible where evidence is available.
The EU Commission has calculated a benchmark value of embedded carbon for every commodity in scope when manufactured in Europe. The CBAM levy will be due on emissions embedded which are above the benchmark value.
What is changing?
CBAM scope is expected to widen. The European Commission has proposed adding a large set of downstream iron/steel and aluminium products (around 180 additional CN codes), with an intended start date of 1 January 2028 (subject to adoption).
The EU Commission continues to respond dynamically to feedback from member states. Exemptions, changes and temporary suspensions should be expected. ChamberCustoms and The British Chambers of Commerce have their fingers on the pulse to analyse the latest information and inform our customers.
Meanwhile, UK exporters will need to collect robust emissions data, make sure it stands up to scrutiny, and be ready for verification. CBAM compliance has now become a strategic advantage in maintaining strong and credible relationships with EU customers.
Next steps for UK suppliers
CBAM is now a live commercial reality for EU importers and, by extension, for UK suppliers.
While the legal obligation sits with EU customers, the quality and credibility of the data you provide will increasingly influence pricing, supplier selection and long-term trading relationships. Businesses that can supply accurate and verifiable emissions data will be better placed to protect margins and retain EU customers.
ChamberCustoms, part of the British Chambers of Commerce, supports UK exporters with:
Embedded emissions calculations for CBAM-in-scope goods
A structured CBAM monitoring strategy
Knowledge-transfer sessions for stockists, distributors and businesses that wish to build in-house CBAM capability
CBAM will continue to evolve, and we monitor developments closely to provide clear, commercially focused guidance for UK businesses trading with the EU.
If you would like to understand how CBAM applies to your products, customers or supply chains, our team would be pleased to discuss how we can support you.