Matching of credit notes adjusts output tax liability, with additions and interest where recipients fail to declare corresponding input tax reductions. Section 43 requires matching supplier credit notes with corresponding reductions in recipient input tax credit in valid returns; matched claims are accepted and communicated. Discrepancies or undeclared credit notes are communicated to both parties, and unrectified discrepancies or duplicative reductions are added to the supplier's output tax liability in specified returns. Suppliers whose liability is increased by such additions must pay interest from the date of the reduction claim; if the recipient subsequently declares the credit note within the prescribed time the supplier may reduce the added amount and obtain a refund of interest via the electronic cash ledger, limited to interest paid by the recipient.