Matching of credit notes requires supplier reductions to align with recipient input tax adjustments; discrepancies increase supplier liability. Credit notes must be matched so a supplier's reduction in output tax aligns with the recipient's reduction in input tax claimed in a valid return; matched claims are accepted and communicated. Discrepancies where supplier reductions exceed recipient declarations are notified and, if not remedied within the prescribed return period, the unreconciled amount is added to the supplier's output tax liability. Duplication of reduction claims is similarly corrected by adding the amount back to the supplier's liability. Interest accrues on added amounts from the date of the original reduction, and interest paid may be refunded to the supplier up to the interest paid by the recipient when the recipient subsequently declares the credit note.