GSTR-1
What GSTR-1 means, how it works, a worked example, the mistakes we see and the questions founders ask.
DefinitionGSTR-1 is the monthly or quarterly GST return in which a registered business reports every outward supply, invoice by invoice for B2B sales, due by the 11th of the following month.
GSTR-1 is the sales side of GST. It lists each B2B invoice with the buyer's GSTIN, summarises B2C sales, and records credit notes, exports and amendments. What you file flows into your buyers' GSTR-2B, which is the basis of their input tax credit, so a late or wrong GSTR-1 hurts your customers as well as you. Monthly filers submit by the 11th; businesses under the QRMP scheme with turnover up to ₹5 crore file quarterly by the 13th and can upload invoices monthly through the IFF. You meet it every month from the moment you are registered. What it means for you: invoice data must be clean, with correct GSTINs and HSN codes, and it must reconcile with GSTR-3B, because the portal now blocks GSTR-1 if the previous GSTR-3B is pending.
How GSTR-1 works
GSTR-1 is the outward supply return: every B2B invoice with the customer's GSTIN, B2C supplies summarised by State and rate, exports, credit and debit notes, advances and amendments to earlier periods. It is filed monthly by the 11th, or quarterly by the 13th of the month after the quarter under the QRMP scheme for businesses with aggregate turnover up to ₹5 crore, who can still push B2B invoices monthly through the Invoice Furnishing Facility so customers get their credit on time.
What you file in GSTR-1 lands in your customers' GSTR-2B as their input tax credit, so errors here cost the customer money and attract their calls. Since August 2024, GSTR-1A lets a filer correct or add invoices for the same period before GSTR-3B is filed; older periods are amended in the next GSTR-1.
A late GSTR-1 costs ₹50 a day (₹20 for a nil return), capped by turnover, and since 2021 the portal blocks GSTR-3B until the previous period's GSTR-1 is filed. Invoices not reported by 30 November of the following year cannot be added at all, which also locks the customer out of that credit.
A Pune agency with ₹3 crore turnover opts for QRMP. It uploads its B2B invoices through IFF by the 13th of each month so clients see the credit in their 2B, and files the quarterly GSTR-1 by 13 July for April to June. In August a client points out a wrong GSTIN on a June invoice; the agency amends it in the July to September GSTR-1 and the credit appears in the client's October 2B.
Mistakes we see with GSTR-1
- Reporting a B2B invoice as B2C because the customer's GSTIN was not collected, so the customer loses the credit.
- Filing GSTR-3B with tax figures that do not match GSTR-1, which triggers an automated DRC-01B notice to explain the difference.
- Missing the 30 November cut-off for the previous year's unreported invoices, after which neither side can fix it.
Last updated 19 October 2026. Checked against the MCA, GST, Income-tax and Trade Marks rules in force for October 2026.
Where you will meet this term
Questions founders ask about GSTR-1
What is the due date for GSTR-1?
The 11th of the following month for monthly filers, and the 13th of the month after the quarter for QRMP filers (turnover up to ₹5 crore), who may also use the Invoice Furnishing Facility by the 13th of the first two months.
What is the late fee for GSTR-1?
₹50 a day (₹25 CGST and ₹25 SGST), ₹20 a day for a nil return, capped between ₹500 and ₹10,000 depending on turnover. The portal also blocks the next GSTR-3B until GSTR-1 is filed.
How do I correct a mistake in a filed GSTR-1?
For the same period, through GSTR-1A before GSTR-3B is filed. For an earlier period, by amending the invoice in the next GSTR-1 under the amendments tables, within the 30 November deadline of the following year.