IGST refunds for exported goods require accurate GST and Customs filings and automated invoice-level matching for processing. IGST refunds are available to registered exporters who paid IGST on zero-rated supplies, with the shipping bill deemed an application once EGM and a valid GST return are filed. An automated refund module matches invoice-level GSTN data with ICES shipping bill data; failures at GSTN or Customs due to missing returns, incomplete invoice details, GSTIN or invoice mismatches, duplicate transmissions, or unavailable gateway EGMs prevent processing. Exporters must correct GST returns (using Form 9A where allowed), ensure electronic EGM filing by carriers, validate PFMS bank details, and resolve IEC suspensions to enable refund credit.