GSTR-1 is the return of outward supplies. It tells the government, and your buyers, what you sold. Each B2B invoice you report flows into your buyer's GSTR-2B, which is how they claim credit.
Due dates (as of October 2026)
- Monthly filers
- 11th of the following month.
- Quarterly filers under QRMP
- (turnover up to ₹5 crore): 13th of the month after the quarter, with the optional Invoice Furnishing Facility for B2B invoices in the first two months.
Returns cannot be filed more than three years after their due date.
What goes in it
| Table | Contents |
|---|---|
| B2B | Invoices to registered buyers, by GSTIN |
| B2CL | Inter-state invoices to consumers above ₹1 lakh |
| B2CS | Other consumer sales, summarised by rate and state |
| Exports | Export invoices, with or without IGST |
| Credit and debit notes | Notes issued in the period |
| HSN summary | Quantity and value by HSN code, B2B and B2C separately |
| Documents issued | Invoice series used and cancelled |
Mistakes can be corrected in GSTR-1A before GSTR-3B is filed, or in a later GSTR-1.
MatruOS builds a GSTR-1 file from your invoices, with B2B, B2CS and HSN lines.