GSTR-1 is the statement of outward supplies — essentially your sales — for a period. It reports B2B and B2C invoices, credit and debit notes, exports and an HSN summary. The data a buyer sees in their GSTR-2B flows from suppliers’ GSTR-1 filings.
It is filed monthly, or quarterly under the QRMP scheme for smaller taxpayers. Accurate GSTR-1 filing is what lets your customers claim their input tax credit.
Inside the return, detail varies by counterparty. B2B supplies are reported invoice by invoice against each buyer's GSTIN; larger inter-state B2C invoices above a prescribed value are also itemised; the rest of consumer sales collapse into rate-wise, state-wise totals. Credit and debit notes are reported with a reference to the original supply, exports carry shipping-bill details, and a documents-issued table accounts for every invoice number in the series — including the cancelled ones.
Timing decides who sees what. Invoices filed by the period's cut-off surface in buyers' GSTR-2B for that month; anything filed late slips into the next month's statement, delaying customers' credit by a full cycle. Filing is also sequential — a pending earlier return blocks the later ones — and the declared liability flows straight into GSTR-3B, so GSTR-1 is effectively the source document for the payment return that follows.
Because every B2B line feeds a buyer's credit statement, suppliers who misquote GSTINs or miss credit notes generate reconciliation work for their customers as much as for themselves. The classic errors are missed credit notes leaving declared liability overstated, an HSN summary that does not total back to the invoice-level data, and supplies reported in the wrong period — each harmless-looking, each a mismatch somebody must later explain in writing.