Refunds of VAT can occur when input tax exceeds output tax on a VAT return. Repayment supplement will be added to a repayment if HMRC failed to issue a repayment instruction within a 30-day period. Repayment supplement is the greater of £50 or 5% of the repayment of VAT due. Overpayments of VAT will be refunded provided the claimant will not be unjustly enriched. The right to a refund and, if appropriate, interest is limited to VAT paid in the four years prior to the claim. In cases of official error there are procedures available to claim compensation from HMRC.