Invoice-based refund entitlement for Canteen Stores Department requires specified filings and inter-authority communication for payment. CSD refund claims are invoice-based and filed quarterly on FORM GST RFD-10A manually until an online utility exists; applications must include an undertaking of goods receipt, declaration of no prior claims, copies of FORM GSTR-3B and GSTR-2A (with attested invoices not in GSTR-2A), and bank details. The proper officer issues an acknowledgement, may issue a single deficiency memo, validates GSTIN and return details on the portal, relies on GSTR-2A as evidentiary support, and issues separate sanction/rejection orders and payment advice per tax head, with inter-authority communication required for payment processing.