What UK CBAM records must importers keep?

HMRC says anyone importing CBAM goods into the UK must keep records of those goods from 1 January 2027. That includes importers below the registration threshold who need to show why they were not liable to register.

One record for each imported good

For each CBAM good, capture:

• the 8-digit commodity code and product description
• the date it passed the tax point—when it entered the UK or cleared customs, as applicable
• the customs value used for the registration-threshold calculation
• the net mass in kilograms, excluding packaging
• evidence supporting any exemption or excluded treatment
• a declaration, shipment or internal reference that leads back to the source

If the business submits a return, HMRC also requires records of the quarter in which the goods passed the tax point and proof of origin.

Documents that can support the line

HMRC lists records such as import declarations, import entry acceptance advice, bills of lading, commercial documents, records discharging a customs procedure and customs-duty relief documents. Weight may also be supported by invoices, carrier records or packing lists.

You do not need to copy every source document into one tool. Give each transaction a durable reference and keep the original in the business’s secure document system.

Weight needs particular care

The record should show net mass at the time of import, excluding packaging, in kilograms. Do not substitute gross shipping weight. HMRC provides specific rounding instructions and says the importer is responsible for obtaining the correct figure.

Registration will also require estimated weight for the next 12 months by sector, so retain how that forecast was built as well as the final transaction weights.

Additional evidence depends on the route used

• Actual emissions: retain the relevant verification report or verification summary.
• Carbon Price Relief: retain the carbon pricing verification form and the calculation evidence.
• Exemptions: keep evidence of UK origin, returned goods relief, temporary admission or other treatment relied on.
• Corrections or repayments: preserve the reason, calculation and documents supporting the change.

A workable monthly process

1. Receive the customs export. Get transaction data from every broker or import channel.
2. Match the documents. Link declarations, invoices and weight evidence to the same import reference.
3. Review gaps. Keep missing codes, value, weight, origin or evidence visible and assigned.
4. Freeze the review. Record who checked the month, when and which HMRC rules snapshot was used.