Refund of IGST: export refunds require shipping bill filing, valid GSTR-3B, Aadhaar and customs confirmation. Refunds of IGST on exports are triggered when a shipping bill or bill of export is deemed an application upon transmission of export documents and confirmation by Customs, subject to the exporter having filed a valid FORM GSTR-3B, rectified any GSTR-1 mismatches, and completed Aadhaar authentication; Customs confirmation of export and electronic transmission of invoice details enable processing, and refunds are electronically credited to the validated bank account, while claims may be withheld for Commissioner requests, Customs violations, or credential verification based on risk analysis.