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

Canonical: https://senseible.earth/answers/uk-cbam-repayment-refused-economic-burden

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)](https://senseible.earth/answers/uk-cbam-amend-return-three-years)
- [UK CBAM return calendar](https://senseible.earth/answers/uk-cbam-returns-after-first-year)
- [Record keeping and the penalty](https://senseible.earth/answers/uk-cbam-records-penalty-and-six-year-clock)

Sources: [HM Revenue and Customs, Keeping records for Carbon Border Adjustment Mechanism (CBAM) (updated 3 November 2026)](https://www.gov.uk/guidance/keeping-records-for-carbon-border-adjustment-mechanism-cbam), [HM Revenue and Customs, Carbon Border Adjustment Mechanism (CBAM): Policy summary (updated 2 November 2026)](https://www.gov.uk/government/publications/carbon-border-adjustment-mechanism-cbam-policy-summary/carbon-border-adjustment-mechanism-cbam-policy-summary)

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.