What Is GSTR-1?
GSTR-1 is the return where you declare every sale your business made during the month or quarter to the GST system. Invoices, credit notes, debit notes, advances received, all of it. It is governed by Section 37 of the CGST Act, 2017, and the data you report here auto-populates your buyer’s GSTR-2B, which is the statement they use to claim input tax credit on purchases from you.
File late and two things happen: you pay a late fee, and your buyer’s ITC gets stuck. That second part is what makes GSTR-1 a problem beyond your own books. Say a packaging supplier in Thane files ten days late. He is not just paying Rs.500 in penalties; he is holding up Rs.67,400 in ITC for a retail chain in Kochi that needed that credit to offset its own GSTR-3B liability.
What Goes Into GSTR-1?
Thirteen tables in total, but five matter most for SMEs:
| Table | What It Covers | Key Detail |
|---|---|---|
| Table 4 | B2B invoices | Sales to registered buyers with GSTIN, invoice number, HSN, tax breakup |
| Table 5 | B2C large | Interstate sales above Rs.2.5 lakh to unregistered buyers |
| Table 7 | B2C small | All other B2C sales, consolidated rate-wise |
| Table 9 | Amendments + CN/DN | Corrections to prior-period invoices, credit/debit notes |
| Table 12 | HSN summary | HSN-wise breakup; mandatory for B2B, optional B2C under Rs.5 crore |
The Table 4 vs Table 7 distinction trips up first-time filers. Sell Rs.3,10,000 worth of goods to an unregistered buyer in another state? That is Table 5 (B2C large), not Table 7. Wrong table, wrong bucket, mismatch with GSTR-3B.
How Is GSTR-1 Filed?
Due date depends on turnover. Monthly filers (above Rs.5 crore) submit by the 11th of the following month. QRMP filers (up to Rs.5 crore) get until the 13th of the month after the quarter.
Say a garment store in Gachibowli, Hyderabad files monthly. March 2026: 142 B2B invoices, 8 credit notes, roughly 900 B2C transactions. The accountant uploads B2B invoices via the JSON tool by April 8th, reviews the HSN summary, submits. Miss April 11th and late fee kicks in at Rs.50/day, capped at Rs.5,000. Nil returns: Rs.20/day, capped at Rs.500.
QRMP filers get an extra tool called the Invoice Furnishing Facility (IFF): upload B2B invoices in the first two months of each quarter so buyers do not wait three months for ITC. Most small businesses we work with did not know IFF existed until their biggest buyer complained about missing credits.
Why Does GSTR-1 Matter for Indian Businesses?
Your buyer’s ITC depends entirely on your GSTR-1. Their GSTR-2B auto-populates from what you file; miss an invoice and the buyer’s credit vanishes until you amend. File a wrong GSTIN in a B2B entry and the credit lands in someone else’s GSTR-2B or nowhere at all.
The GSTR-1 vs GSTR-3B mismatch is the other headache. Outward supply totals across Tables 4, 5, 6, 7, and 8 must match GSTR-3B Table 3.1. We have seen electronics retailers in Vizag get automated notices under FORM GST ASMT-10 for differences as small as Rs.4,200, usually one credit note reported in 3B but skipped in GSTR-1.
Sequential filing makes it worse: current period’s GSTR-1 will not file until the previous one is done. Miss one month and the backlog compounds.
How Does Petpooja Invoice Handle GSTR-1?
Petpooja Invoice generates GSTR-1-ready data from your invoices. B2B entries carry the buyer’s GSTIN (validated against the IRP during e-invoice generation), HSN codes pull from the item master, and credit/debit notes land in the right tables without manual sorting. Tally sync means no re-entry. Clients like Amber Boxes run this across their retail billing setup, cutting down month-end GSTR-1 prep time considerably.
Frequently Asked Questions
11th of the following month if you file monthly (above Rs.5 crore turnover). 13th of the month after the quarter for QRMP filers. Late fee: Rs.50/day.
Yes. Nil GSTR-1 is mandatory even with zero transactions. Late fee: Rs.20/day, capped at Rs.500. Skip it and GSTR-3B for the same period gets blocked.
The Invoice Furnishing Facility lets quarterly filers upload B2B invoices in months one and two of each quarter, so buyers claim ITC monthly instead of waiting for the quarterly GSTR-1. Due by the 13th. Optional, but worth using if your buyers file regularly.
Directly. Your GSTR-1 feeds the buyer’s GSTR-2B. Missing invoice or wrong GSTIN means the buyer cannot claim credit until you file an amendment next period.
The GST portal flags mismatches and sends a notice under FORM GST ASMT-10, which can escalate to demand proceedings under Sections 73 or 74 of the CGST Act. Even small differences get flagged.
Yes, via Table 9. Corrections to B2B invoices, credit notes, and debit notes can be filed until the September return of the following FY, or the annual return date, whichever is earlier.
