Key points:
- UK CBAM applies to imports of aluminium, cement, fertiliser, hydrogen, and iron and steel from 1 January 2027.
- Importers of £50,000 or more of CBAM goods in 12 months will be liable.
- For each import, they must record net mass in kilograms, excluding packaging, to up to 6 decimal places.
- Forwarders, hauliers and customs brokers do not become the importer by acting on the importer’s behalf.
- Importers that do not keep records may face a £500 fixed penalty.
Who pays
UK CBAM puts a carbon price on imports of five sectors: aluminium, cement, fertiliser, hydrogen, and iron and steel. The aim is for imported goods to face a carbon cost comparable to that paid by UK producers.
The tax is paid by the importer. According to HMRC, this is the person named on the import declaration, even if someone else declares the goods for them. HMRC lists freight forwarders, hauliers (drivers), customs brokers, express operators and fast parcel operators among those who may import goods on someone else’s behalf. In all these cases, the business it is acting for “will still be classed as the importer”.
A business is liable once its CBAM imports reach £50,000 in 12 months, or if it expects to reach that amount within the next 30 days, according to the registration rules.
Gross weight is not enough
This is where transport companies come in. Under HMRC’s record-keeping guidance, importers must keep the following for every CBAM import from 1 January 2027:
- the 8-digit commodity code and a description of the goods,
- net mass in kilograms, excluding packaging, to up to 6 decimal places,
- the value of the goods,
- the date the goods entered the UK or cleared customs,
- proof of origin and evidence of any exemptions.
The records must be kept for 6 years. HMRC lists import declarations, bills of lading, commercial invoices, packing lists and “carrier weight records” among the documents that can support them.
In practice, a CMR or delivery note usually shows gross weight, including pallets and packaging. To get the net figure, importers will need packing lists or data from manufacturers. HMRC notes that weight evidence “might be from manufacturers”.
No border stop, but more data requests
CBAM is not collected at the border. Importers will register from 1 January 2028 and submit their first return and payment by 31 May 2028, covering imports from 2027.
However, importers will need the data from the very first shipment in January. Those who cannot obtain verified actual emissions data must use default values, and failing to keep records may lead to a fixed penalty of £500.
For forwarders and hauliers handling steel, aluminium or fertiliser loads into the UK, this means more requests for accurate documents. Customers may ask for packing lists, net weights and weighbridge records with each consignment, so it pays to agree in advance who provides which data.
For more on the basics, see our guides on who pays UK CBAM and on the HMRC rulebook published earlier this month.
