IGST refund procedures require shipping bill deemed applications, invoice-level GST matching, and verification before disbursement. For exports the shipping bill is deemed to be an application for refund once EGM and a valid return are filed; Customs' ICES module conducts invoice-level matching between Shipping Bill data and GST returns transmitted by GSTN and, if matched, processes electronic credit of IGST. Exporters must accurately report export details in GSTR-3B and GSTR-1 and reconcile aggregate IGST figures; where GSTN transmission is delayed, interim procedures allow sanction of refunds subject to CA certificates, remediation of short payments and post-refund audit and verification by GST field formations.