GSTR-1 reconciliation
Matching your filed GSTR-1 (the outward-supplies return) against your sales register, to catch sales booked but not reported (under-reported liability) and entries reported but not in your books.
GSTR-1 is the return in which a business reports every outward supply — its sales — invoice by invoice. What you file in GSTR-1 flows into your customers' GSTR-2B as their claimable credit, so an error here ripples downstream to everyone you sell to.
GSTR-1 reconciliation compares the invoices in your filed GSTR-1 against your sales register. Sales in your books but missing from GSTR-1 are under-reported liability — a filing gap that invites notices and denies your customer their credit. Entries in GSTR-1 but not in your books are extra or duplicate filings that overstate your liability.
Run monthly alongside the GSTR-2B purchase-side match and the GSTR-3B tie-out, GSTR-1 reconciliation is the outward half of a complete GST close — confirming that what you told the government you sold matches what you actually booked.
