You will need to keep the following records in written (including electronic) form for 6 years from the latest of either the: 

• end of the accounting period they relate to  

Goods and import records you must keep 

Anyone importing CBAM goods into the UK will need to keep records of the CBAM goods they have imported from 1 January 2027.

The records will need to include the following information about each CBAM good, the:

• 8-digit commodity code and description 

• date it passed the tax point (when it first entered the UK or cleared customs) 

• evidence for any exemptions from CBAM 

Records can be import declarations (if you hold this information). They could also be other documents relating to the imported CBAM goods.

These might be from manufacturers, to show the weight of goods, or from suppliers, to display the value. 

If you submit a CBAM return, you will also need to keep records of: 

• the quarter in which the goods passed the tax point (when the goods first entered the UK or they cleared customs) 

Customs documents 

If you’re using a customs document as a record for imported CBAM goods, this could include:

• discharge of a customs procedure (other than Temporary Admission) 

• commercial documents, including record of movement of goods in the UK 

• UK Customs Duty documents, including eligibility for relief 

• repayment or remission of duty documents 

• evidence of UK origin materials, already carbon taxed in reimported goods 

What records you need to keep if you report actual emissions 

If you choose to report actual emissions for the CBAM goods you import, you must keep evidence that the emissions data you are reporting has been verified. 

You’ll get the evidence you need from your supplier in the form of a verification report, or verification summary, that contains the relevant emissions data. 

You’ll need to keep the verification report, or verification summary, relevant to the emission intensity reported on your tax return for 6 years. 

HMRC will publish further detail about verification requirements before 1 January 2027. 

You must use a default value if: 

• actual emissions data is not available to you

• you do not have evidence that the emissions data you are reporting has been verified 

We’ll set the default values for CBAM goods later this year. 

We’ll provide guidance on monitoring, verifying and reporting actual emissions later this year. 

Weight of goods records you should keep 

Records for imported CBAM goods must show the weight excluding packaging (net mass) in kilograms (kg). This should be the weight of the CBAM good at time of import into the UK. 

Enter, up to 6 decimal places, the net mass of the goods as described in DE 6/8 (Description of Goods).

Where a net mass greater than 1kg includes a fraction of a unit (kg), it may be rounded to the nearest kg. Where the fraction is:

• 0.499999kg or less — round down to the nearest kg

• 0.5kg or more — round up to the nearest kg

A net mass less than 1kg should be entered as ‘0.’ followed by up to 6 decimal places, discarding all ‘0’s at the end.

For example:

• 0.123kg for a package of 123 grams (g)
• 0.00304kg for a package of 3g and 40 milligrams (mg)
• 0.000654kg for a package of 654mg

Examples of records of weight include import declarations, commercial invoices, carrier weight records, bill of lading or packing lists. 

Registration for CBAM will open on 1 January 2028. You’ll need to provide:

• estimates of the weight of CBAM goods you expect to import in the next 12 months
• an estimate for each sector (aluminium, cement, fertiliser, iron and steel, hydrogen)

You’ll also need to keep evidence of how you estimated weight.

When you come to completing your CBAM returns, you’ll need to know the actual weight of the imported CBAM goods in that returns period.

You may be able to get this information from your import declarations or supplier. You’re responsible for getting the information about the correct weight. 

Tax relief and repayment records you must keep 

You can claim relief to reduce the amount of CBAM due if you can show you have already paid a charge on the CBAM goods to a qualifying carbon pricing scheme. 

Keep copies of the carbon pricing verification form completed by a suitable verifier as evidence for your calculation. We’ll publish further detail about verification later this year. 

If you are claiming Carbon Price Relief through your CBAM return, you will need to keep records of: 

• the qualifying carbon pricing scheme your CBAM goods were subject to  

• how the goods qualify for Carbon Price Relief — including verified effective carbon price calculations

• which elements of the qualifying carbon price scheme you used to decide the price

• how you adjusted down the CBAM liability — including exchange rates used to convert to pound sterling (GBP) 

Repayment claims records 

You need to keep records of claims for CBAM-related repayments from HMRC. You might claim a repayment if you made an error on your return that led to an overpayment. 

The details you need to keep include the: 

• date the error was found 

• accounting period which the claim relates to 

• full details of the CBAM goods (from the relevant return) 

• date the CBAM liability was originally paid 

You’ll need to keep these records for 6 years from the date you send the claim.

HMRC will only repay overpaid CBAM for the 3 years before you make a claim. 

A claim for repayment may be refused if HMRC finds: 

• you’ve passed the economic burden of the amount you are looking to claim on to another person

• payment of the claim would unjustly enrich you

In these circumstances, a claim will not be refused on the grounds of unjust enrichment if you: 

• agree to reimburse your customer

• meet the conditions of HMRC’s reimbursement scheme

Reimbursement records

Where reimbursement is made, you should keep records of: 

• names and addresses of each person the claimant reimburses or plans to reimburse 

• the amount to be reimbursed to each person 

• amount of interest included in the total amount reimbursed to each person

• date that each reimbursement was made 

These records need to be kept for the period of 6 years beginning from either (whichever is later) the: 

• last day of the accounting period to which the records relate 

• day the claimant makes the reimbursement to which the records relate 

Exemption from CBAM records you must keep 

You need to keep records for imported CBAM goods you believe are exempt from the scope of CBAM. 

CBAM goods can be exempt if: 

• they are for private use 

• they are of UK origin

• Returned Goods Relief is claimed

• they came into the UK under Temporary Admission with full relief from Customs Duty

Private use 

Keep records of any CBAM goods that you import into the UK for private use. This could include:

• evidence of the good being used to build something for private use 

• proof that you still own the goods 

• proof of how you use the goods for private use 

 UK origin 

Keep records of any CBAM goods you import which are of UK origin (under the non-preferential rules of origin). This could include: 

• any information you have relied on as ‘importers knowledge’ 

Keep records of Returned Goods Relief if you reimport unaltered CBAM goods into the UK within 3 years of export. This includes: 

• proof of earlier UK export 

• proof of reimport into the UK within 3 years 

• evidence the goods are in the same state 

• serial or batch numbers or packing lists 

Temporary Admission with full relief 

Keep records of CBAM goods which enter the UK under Temporary Admission with full relief from import duty. This includes: 

• evidence that the good is eligible for full relief 

• the import declaration (showing full relief) for the good entering the UK 

• proof that the goods are following the terms of Temporary Admission, for example, the good has not been released into free circulation