Input tax credit matching: electronic discrepancy notices require rectification or trigger automatic reversal into recipient output tax liability. Electronic notification of input tax credit discrepancies in FORM GST ITC-1 must be sent to supplier and recipient by the last date of the month in which matching occurs. Suppliers may rectify by adding or correcting outward supply details; recipients may rectify by deleting or correcting inward supply details in the return for the month the discrepancy is communicated. If neither rectifies, the discrepancy amount is added to the recipient's output tax liability in FORM GSTR-3 for the month following the communication.