GSTR-1 Filing Guide: How to Report Your Sales Correctly

GSTR-1 is the return where you tell the GST system what you sold. Your buyers' input tax credit, your own GSTR-3B liability and much of the department's matching all start from this one statement, so getting it right each month saves trouble everywhere else.

This guide covers who files GSTR-1, the due dates, what goes in each table, a step-by-step filing walkthrough, how corrections work through GSTR-1A, and the mistakes that cause most notices.

Who needs to file GSTR-1?

Every regular taxpayer registered under GST files GSTR-1, including those who had no sales in a period (they file a nil return). The following do not file GSTR-1:

• Composition taxpayers (they use CMP-08 and GSTR-4)
• Input Service Distributors (GSTR-6)
• Non-resident taxable persons (GSTR-5)
• Persons deducting TDS (GSTR-7) or e-commerce operators collecting TCS (GSTR-8)
• Online information and database access service providers from outside India (GSTR-5A)

If you are a regular taxpayer, you choose between monthly and quarterly filing. Quarterly GSTR-1 is available if your aggregate turnover in the preceding financial year was up to ₹5 crore, or, for a business registered in the current year, if you expect turnover to stay within ₹5 crore. Quarterly filing goes together with the QRMP scheme — see QRMP scheme and IFF.

What is the due date for GSTR-1?

Filing frequency	Due date	Example
Monthly	11th of the following month	September 2026 return due 11 October 2026
Quarterly (QRMP)	13th of the month after the quarter	July–September 2026 due 13 October 2026
IFF (QRMP, optional, months 1 and 2)	1st to 13th of the following month	July 2026 invoices by 13 August 2026

The government can extend these dates by notification, so check the portal around the deadline. Filing on time matters for two reasons: your buyers cannot claim input tax credit on invoices that are not in GSTR-1, and your GSTR-3B liability is auto-populated from it.

The three-year time bar

Since the GSTN's June 2025 advisory, the portal enforces the Finance Act, 2023 change that bars filing a return after three years from its due date. This covers GSTR-1, GSTR-3B, GSTR-4, GSTR-5, GSTR-5A, GSTR-6, GSTR-7, GSTR-8 and GSTR-9. A GSTR-1 that is more than three years overdue can no longer be filed at all, so very old pending returns need urgent attention.

What goes into each GSTR-1 table?

GSTR-1 is divided into tables by type of supply. The ones most small businesses use are:

Table	What to report	Level of detail
4A, 4B, 6B, 6C (B2B, SEZ, deemed exports)	Sales to registered buyers	Invoice-wise with buyer GSTIN
5 (B2C Large)	Inter-state sales to unregistered buyers above the notified invoice value	Invoice-wise
7 (B2C Others)	All other sales to unregistered buyers	Rate-wise and state-wise summary
6A (Exports)	Exports with or without payment of IGST	Invoice-wise with shipping bill details
8	Nil-rated, exempt and non-GST supplies	Summary
9B (CDNR / CDNUR)	Credit and debit notes	Note-wise
11	Advances received and adjusted	Summary
12	HSN-wise summary	HSN code, quantity, taxable value, tax
13	Documents issued	Serial ranges of invoices, notes, challans

The HSN summary in Table 12 needs a minimum number of digits. Taxpayers whose aggregate annual turnover exceeds ₹5 crore enter at least 6 digits; others enter at least 4 digits. For how many digits go on the invoice itself, see HSN code digits on invoice.

E-invoices and GSTR-1

If you generate e-invoices, the B2B, export and credit/debit note details from your IRNs are auto-populated into GSTR-1 on the portal. You still need to review them, add B2C sales and the HSN and document summaries, and then file. Auto-population does not mean auto-filing.

How do I file GSTR-1 on the GST portal?

1. Log in at gst.gov.in and go to Services > Returns > Returns Dashboard.
2. Select the financial year and the return period, then click Search.
3. On the GSTR-1 tile, click Prepare Online (or upload a JSON file prepared with the offline tool or your billing software).
4. Open each relevant table and add or review entries. For B2B invoices, enter the buyer's GSTIN, invoice number, date, value, place of supply, rate and taxable value.
5. Fill the B2C summary, nil/exempt summary, HSN summary (Table 12) and documents issued (Table 13).
6. Click Generate Summary and wait a few minutes for the portal to process it.
7. Review the summary, then click Preview and download the draft PDF to check totals against your sales register.
8. Tick the declaration, choose the authorised signatory and click File Statement.
9. File with DSC (mandatory for companies and LLPs) or EVC (OTP to the registered mobile and email).
10. Note the ARN that appears after filing; a confirmation also goes to your registered email.

Most billing software can export a GSTR-1 JSON in the portal's format. Billing Software by Betterwork, for example, produces GSTR exports from the invoices, credit notes and HSN data already in your books, so you upload one file rather than typing hundreds of rows.

Worked example: a Pune hardware shop's monthly GSTR-1

A Pune hardware shop (monthly filer, registered in Maharashtra) has these September 2026 sales:

Sale	Taxable value	Rate	Tax
B2B invoice to a Mumbai contractor (registered)	₹1,20,000	18%	CGST ₹10,800 + SGST ₹10,800
B2B invoice to a Bengaluru builder (registered)	₹80,000	18%	IGST ₹14,400
Counter sales to walk-in customers (Maharashtra)	₹2,50,000	18%	CGST ₹22,500 + SGST ₹22,500
Credit note to Mumbai contractor for returned goods	₹10,000	18%	CGST ₹900 + SGST ₹900 (reduction)

How it is reported:

• The two B2B invoices go into Table 4A, invoice-wise, with the buyers' GSTINs. The Bengaluru sale shows place of supply as Karnataka, so it carries IGST.
• The ₹2,50,000 counter sales go into Table 7 as a single summary row: Maharashtra, 18%, taxable value ₹2,50,000.
• The credit note goes into Table 9B (CDNR) against the contractor's GSTIN.
• The HSN summary lists the codes and quantities of everything sold.

Net liability that flows to GSTR-3B: taxable value ₹4,40,000 (₹4,50,000 less ₹10,000); IGST ₹14,400; CGST ₹32,400 (₹10,800 + ₹22,500 − ₹900); SGST ₹32,400. Total tax ₹79,200. To check these numbers quickly, the GST calculator works per line.

How do I correct a mistake in GSTR-1?

There are two routes, depending on timing.

GSTR-1A: before you file GSTR-3B

GSTR-1A is an optional facility that lets you add a missed invoice or amend one reported in the current period's GSTR-1, as long as you have not yet filed GSTR-3B for that period. It opens on the later of the GSTR-1 filing date or its due date and closes once GSTR-3B is filed. The portal FAQ notes it can be filed only once per tax period. GSTR-1A cannot change the recipient's GSTIN; that needs an amendment in a later GSTR-1.

GSTR-1A matters more now because, from the July 2025 tax period, the liability auto-populated in GSTR-3B from GSTR-1/1A/IFF can no longer be edited in GSTR-3B. If the outward liability is wrong, GSTR-1A is the place to fix it before you pay. A saved but unfiled GSTR-1A blocks GSTR-3B filing, so either file it or reset it.

Records you add in GSTR-1A reach your buyer in their GSTR-2B for the next period, not the current one.

Amendment tables in a later GSTR-1

Once GSTR-3B for the period is filed, corrections go into the amendment tables (9A for invoices, 9C for notes, 10 and 11 for B2C and advance amendments) of a subsequent GSTR-1. The cut-off for amending is linked to 30 November after the end of the financial year or the filing of the annual return, whichever is earlier.

Corrections to value often need a credit note under GST rather than an amendment, especially when the buyer returned goods or got a discount after the sale.

What is the late fee for GSTR-1?

Section 47 of the CGST Act sets a late fee of ₹100 per day under the CGST Act (and the same under the state Act), up to ₹5,000, for late statements under Section 37. The government has notified much lower amounts for most taxpayers, with separate caps for nil filers and by turnover. The fee keeps running until the statement is filed. For the full picture of fees and interest, read GST late fee and interest.

Common mistakes in GSTR-1

• Wrong buyer GSTIN. The credit lands with someone else, your buyer complains, and you need an amendment. Validate GSTINs before invoicing with the GSTIN validator.
• Wrong place of supply. Charging CGST+SGST on an inter-state sale (or IGST on an intra-state sale) is not fixed by simply changing the tax head; it needs correction and possibly a refund claim.
• Putting B2B sales in B2C. If a buyer gave a GSTIN, the invoice must go in B2B, or the buyer loses credit.
• Missing credit notes. Unreported credit notes inflate your liability.
• HSN summary not matching totals. The HSN table should reconcile with the invoice-level values.
• Leaving an IFF or GSTR-1A saved but unfiled. Both can block the next filing step.
• Filing GSTR-3B before GSTR-1. Liability will not auto-populate correctly.

Key takeaways

• GSTR-1 is due on the 11th (monthly) or 13th after the quarter (QRMP).
• B2B invoices are reported invoice-wise; most B2C sales are summarised by rate and state.
• E-invoice data auto-fills GSTR-1, but you must still review, complete and file it.
• Use GSTR-1A to fix the current period before GSTR-3B; later fixes go into amendment tables.
• GSTR-3B outward liability is now locked to GSTR-1/1A values, so accuracy here is everything.
• Returns more than three years past their due date can no longer be filed.

For how GSTR-1 and GSTR-3B fit together, see GSTR-1 vs GSTR-3B, and for the payment return itself, the GSTR-3B filing guide.

This guide is general information, not tax advice. Rules last checked on 20 October 2026; confirm with your tax professional for your situation.