The mismatch in reduction in output tax liability is due to the incorrect details entered by the recipient of the supply. What is the procedure to followed by the supplier?

1. If there is a mismatch in the claim of reduction of output tax liability, a communication in FORM GST MIS-3 will be sent to the supplier and a communication in FORM GST MIS- 4 will be sent to the recipient of such supply.
2. If the discrepancy is due to the incorrect particulars entered by the recipient, then the recipient can rectify such discrepancy in its return for the month in which GST MIS-4 is communicated to him.
3. Once the discrepancy is rectified and the reduction in output liability is matched, a communication in
   FORM GST MIS-3 will be sent to the supplier and the claim of reduction in output tax liability will be finally accepted.
4. However, if the recipient does not rectify the discrepancy in the month in which such discrepancy is communicated, the amount of tax payable on account of such discrepancy will be added to the output tax liability of the supplier for the month succeeding the month in which FORM GST MIS-4 is communicated to the recipient.

(ICAI FAQ PUBLICATIONS 06-09-2017 RETURNS : FAQ NO.43)