Matching of input tax credit: discrepancies may be added to recipient's output tax liability and attract interest. Matching of inward supplies with suppliers' outward returns and import IGST determined acceptance of input tax credit; discrepancies or undeclared outward supplies were communicated to both parties and, if not rectified by the supplier within the prescribed period, the disputed amount or duplicated claim was added to the recipient's output tax liability and attracted interest from the date of availing credit, while subsequent supplier rectification could allow reduction of that addition and refund/credit of interest subject to prescribed limits.