Input tax credit matching dictates acceptance, reversal and addition to output tax liability based on supplier reporting and duplication checks. Matching of inward supplies with supplier returns, import IGST payments, and duplication checks determines input tax credit entitlement. Matched claims are accepted and communicated. Discrepancies or non-declaration are communicated to both parties; unrectified discrepancies and duplication are added to the recipient's output tax liability in the prescribed month. The recipient may reverse such additions if the supplier rectifies within the specified period. Interest runs on added amounts from the date credit was availed; refunded interest on later acceptance is credited to the electronic cash ledger, capped by the interest paid by the supplier. Improper reductions are restored with prescribed interest.