Hi Stuart Downer,
Claiming a duty repayment is governed by the Customs legislation covering repayments and remissions of duties. If the goods were imported to GB before 01/01/2021, a claim for repayment will be covered under the Union Customs Code (UCC) legislation and for imports on or after this date, a claim will be covered under the Customs (Import Duty) (EU Exit) Regulations 2018.
You can submit your repayment claim for the goods imported up to 3 years ago, as detailed in the guidance at:
How to apply for a repayment of import duty and VAT if you've overpaid (C285)
Apply for repayment of import duty and VAT (CHIEF) - GOV.UK (www.gov.uk)
For imports before 01/01/2021 – EU-Japan trade agreement would apply. Imported goods must have met the relevant rules of origin at the time of import and a valid proof of preference must be held at the time of duty repayment claim as per the requirements of EU-Japan trade agreement.
For imports on or after 01/01/2021 – UK-Japan trade agreement would apply. Imported goods must have met the relevant rules of origin at the time of import and a valid proof of preference must be held at the time of duty repayment claim as per the requirements of UK-Japan trade agreement.
Relevant proof of preference must also be included when submitting the duty repayment claim.
Duty repayment claims are processed and authorised by National Duty Repayment Centre (NDRC) who can advise on any other specific additional information they may require after the applicant has submitted their duty repayment claim.
NRDC can be reached (externally) at: ndrc.nch@hmrc.gov.uk or 03003227064 (option 2).
Thank you.