Recovery of self-assessed tax under section 79: taxpayers given opportunity to explain GSTR-1/GSTR-3B mismatches before action. Where tax shown in outward supply statements but unpaid through the periodic return is short paid or unpaid, the proper officer must issue a DIN-bearing communication allowing a reasonable period to pay or explain GSTR-1/GSTR-3B discrepancies; if the taxpayer neither pays nor satisfactorily explains within the prescribed or extended time, the officer may initiate recovery proceedings under the recovery provisions for self-assessed liabilities.