When can HM Revenue and Customs (HMRC) refuse a repayment of overpaid UK Carbon Border Adjustment Mechanism (CBAM)?

HM Revenue and Customs (HMRC) says a repayment claim may be refused if the importer has passed the economic burden on to another person, or if payment would unjustly enrich it. A claim will not be refused on unjust enrichment grounds if the importer agrees to reimburse its customer or meets HMRC's reimbursement scheme conditions.

The two grounds

• "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"
• Not refused on the unjust enrichment ground if the importer agrees to reimburse its customer, or meets the conditions of HMRC's reimbursement scheme.

The time limit

HMRC will only repay overpaid CBAM for the 3 years before the claim is made. HMRC's summary allows repayment where an error on a return caused an overpayment. Correcting a return has its own window, so read the correction page too.

Records for a claim

• The reason for the claim.
• The date the error was found.
• The accounting period the claim relates to.
• Full details of the CBAM goods from the relevant return.
• The date the CBAM liability was originally paid.
• Keep these for 6 years from the date the claim is sent.

Records if the importer reimburses

• Names and addresses of each person reimbursed or planned to be reimbursed.
• The amount to be reimbursed to each person.
• The amount of interest included in the total reimbursed to each person.
• The date each reimbursement was made.
• Keep these for 6 years from the later of the last day of the accounting period and the day the reimbursement is made.

Why a supplier cares

Our reading, not HMRC's: if your price or contract lets your buyer recover UK CBAM from its own customers, a refund the buyer claims may raise the economic burden question, and the buyer may need to show reimbursement to its customer. Ask your buyer how it plans to handle a refund.

The 3-year window

• The first return, covering 2027, is due by 31 May 2028. Say the amount is paid that day.
• A repayment claim sent on 30 November 2030 is within 3 years of that payment, and inside the 31 December 2030 end of the window to correct that return.
• A claim sent on 10 June 2031 is more than 3 years after the payment, so that amount is not repaid.

Example dates.

What Senseible does here

Senseible reads fuel invoices and electricity bills into dated records, which feed a plant's emissions figure. It does not file repayment claims or advise on reimbursement schemes.

• Correcting a UK CBAM return (window ends 31 December 2030 for the 2027 return)
• UK CBAM return calendar
• Record keeping and the penalty

Sources: HM Revenue and Customs, Keeping records for Carbon Border Adjustment Mechanism (CBAM) (updated 3 November 2026), HM Revenue and Customs, Carbon Border Adjustment Mechanism (CBAM): Policy summary (updated 2 November 2026)

Last reviewed 2026-11-05. HM Revenue and Customs says the details in its policy summary may be subject to change. Re-check the policy summary and the keeping-records page before relying on a date or condition.