Refund of additional IGST for upward export price revisions; claim via FORM GST RFD-01 with prescribed documents and verification. Refund mechanism for additional Integrated Tax (IGST) paid after upward revision of export prices: exporters may file FORM GST RFD-01 electronically (use 'Any other' with prescribed remarks until a separate portal category is available). Jurisdictional GST officers will process claims under rule 89 using GSTN-provided shipping bill and IGST data. Claims require documentary proof (shipping bill, invoices, debit notes, contract, proof of IGST and interest payment, FIRC, accountant's certificate, Statements 9A/9B) and verification of reporting in FORM GSTR-1 and FORM GSTR-3B; sanction and payment orders will be issued in FORM GST RFD-06 and FORM GST RFD-05.