Bank account furnishing requirement mandates prompt portal submission of bank details by registrants, with noncompliance treated as a violation. Mandates furnishing of bank account details on the common portal after GST registration within a short prescribed period, adds violation of that requirement to actionable defaults, and updates registration forms to optionally capture multiple bank accounts; concurrently, introduces mechanisms for electronic cash ledger transfers (FORM GST PMT-09), replaces 'payment advice' with 'payment order' for refund disbursement, and inserts a specific refund route for duty free/duty paid retail outlets at international airport departure areas under FORM GST RFD-10B.