CSD refund procedure mandates manual invoice-based claims with specified documents and inter-authority payment coordination. CSD beneficiaries may claim an invoice based refund of half the tax paid on inward supplies used for subsequent supply by filing FORM GST RFD-10A manually on a quarterly basis with the jurisdictional tax office, accompanied by an undertaking of receipt, declaration of no prior claim, copies of GSTR-3B and GSTR-2A (with attested invoices not reflected), and bank details; the proper officer shall validate returns and GSTIN, issue a single comprehensive deficiency memo if needed, and sanction or reject refunds in FORM GST RFD-06 with payment advice in FORM GST RFD-05, coordinating inter-authority payment as required.