Input tax credit timing clarified: debit note date governs eligibility, with e invoice QR accepted and export duty exclusion for refunds. The date for determining the financial year for input tax credit on debit notes is the date of issuance of the debit note; the delinking amendment governs credits availed on or after the amendment's effective date. Where an e invoice with an embedded IRN exists, the QR code may be produced electronically in lieu of a physical tax invoice during movement of goods. The refund restriction in the proviso applies only to goods actually subject to export duty; goods with nil or exempt export duty are excluded from that restriction.