INTM331019 - Double Taxation applications and claims: Repayment claims from non-residents: Power to enquire into claims
If we decide that we need some more information, whether before or after paying the claim, we must follow a formal enquiry procedure. This starts with a letter telling the claimant that we intend to enquire into the claim.
If you are going to enquire into a claim you must do so within the time allowed. You will normally have at least 12 months from the date the claim reached HMRC (not from the date the claim reached you).
For full guidance on how to enquire into claims, or any amendment by the claimant of a claim made by him, and the exact period allowed see INTM331200.