United Kingdom VAT registered persons seeking repayment of VAT incurred in other member states: Enquiries about claims for VAT incurred in other member states
You should check the other guidance available on GOV.UK from HMRC as Brexit updates to those pages are being prioritised before manuals.
If a claimant enquires about a claim that has been sent to another Member State you should first check if the claim has been received by the other Member State. Claimants are normally sent a receipt when claims successfully reach the Member State of Refund. If the claimant does not know whether the claim has arrived in the Member State of Refund then Online Services can check the system. If a claim is with the Member State of Refund then the claimant should be referred to that Member State. Contact details for other Member State authorities can be found in Section 8 of Notice 723a.