Self-assessed tax recovery under GST requires notice and explanation before section 79 proceedings for GSTR-1 and GSTR-3B mismatches. Recovery under section 79 applies to self-assessed tax remaining unpaid under a return furnished under section 39, including tax on outward supplies declared in GSTR-1 but not included in GSTR-3B, together with unpaid interest. Where a genuine mismatch arises between GSTR-1 and GSTR-3B, the registered person should be given an opportunity to explain the discrepancy or pay the amount within the time specified. Recovery may proceed only if the person fails to respond, fails to pay, or fails to satisfactorily explain the short payment or non-payment.