How to File GSTR-1: A Table-by-Table Guide

GSTR-1 is the return in which you report every outward supply you made in a tax period, invoice by invoice for B2B sales and in consolidated form for most B2C sales. Monthly filers submit it by the 11th of the following month; QRMP filers submit it quarterly by the 13th of the month after the quarter. It is not where you pay tax — that is GSTR-3B — but it is what determines whether your customers can claim credit on your invoices.

What GSTR-1 is and who files it

GSTR-1 is the statement of outward supplies prescribed by Section 37 of the CGST Act read with Rule 59. It is filed by every regular registered taxpayer, including SEZ units and developers and casual taxable persons. It is not filed by taxpayers under the composition scheme (who file CMP-08 and GSTR-4), Input Service Distributors (GSTR-6), non-resident taxable persons (GSTR-5), TDS deductors (GSTR-7) or e-commerce operators collecting TCS (GSTR-8).

The important structural point is that GSTR-1 is declaratory, not payable. You are telling the system what you sold. The liability arising from those sales is discharged in GSTR-3B, which since the July 2025 tax period is auto-populated from GSTR-1 and largely locked against direct editing. In other words, GSTR-1 is now the place where your outward liability is effectively fixed — GSTR-3B just collects it.

Due dates: monthly, QRMP and IFF

The QRMP path is available to taxpayers with aggregate turnover up to ₹5 crore in the preceding financial year. The trade-off — less paperwork, but a lag before your B2B customers see your invoices — is worked through in our QRMP scheme guide. The full year's deadlines for every return type sit in the GST return due dates calendar.

The table-by-table structure

GSTR-1 looks intimidating because it has fourteen-odd tables, but most businesses touch four or five of them. Here is what each is for.

Tables 12 and 13: HSN summary and documents issued

These two used to be the tables people skipped. They are now the two that most often stop a return from validating.

Table 12 (HSN summary) requires HSN reporting at 4 digits where your annual aggregate turnover in the preceding financial year was up to ₹5 crore, and at 6 digits where it exceeded ₹5 crore, under Notification 78/2020-Central Tax. In the phased tightening rolled out through 2025, manual free-text HSN entry was replaced by a dropdown selection from the HSN master, the table was split into separate B2B and B2C tabs, and value validations were introduced that check the HSN-wise totals against the rest of the return. An HSN you have been typing for years will simply not be accepted if it is not in the master. If you are unsure how your turnover is computed for this threshold, see annual aggregate turnover under GST.

Table 13 (documents issued) asks for the serial ranges of every document series you used in the period — from and to, total issued, cancelled, and net. It is a completeness control: it lets the department see that invoice numbers 1 to 480 exist and that you reported 478 of them with two cancelled. Businesses running multiple invoice series across branches or channels routinely under-report here, and the gap is trivially easy to spot.

How GSTR-1 becomes your customer's GSTR-2B

This is the reason GSTR-1 accuracy is not an internal housekeeping matter. Every B2B invoice, debit note and credit note you report flows to the recipient's Invoice Management System dashboard, where they accept, reject or hold it. Their draft GSTR-2B is generated on the 14th of the month from your GSTR-1, GSTR-1A and IFF filings, filtered through those decisions. Since 1 October 2025, GSTR-2B built through IMS is the statutory basis for input tax credit under the amended Section 38 of the CGST Act.

Three consequences follow directly:

• A wrong recipient GSTIN sends the credit to a stranger. The invoice appears in somebody else's IMS and never reaches your customer's GSTR-2B. Worse, GSTIN is one of the fields GSTR-1A cannot amend — the fix is a credit note and a fresh invoice.
• A late GSTR-1 pushes the credit into a later month. File on the 11th and your invoice is in your customer's 2B on the 14th. File on the 25th and it is in next month's.
• A missed invoice is invisible. Your customer holds a valid tax invoice and has paid you, but there is nothing in their 2B to claim against.

The mirror image is also true, which is why this matters when you are the buyer: your own ITC depends on your suppliers filing correctly and on time. A supplier whose GSTIN has been cancelled or who has stopped filing is a live risk to credit you have already accounted for.

Amendments: GSTR-1A and the Table 9/10 route

There are now two correction routes, and using the right one saves a month.

GSTR-1A, introduced from the August 2024 period, is an optional amendment form for the same tax period. It opens from the later of the GSTR-1 due date or the actual filing of GSTR-1, and stays open until you file GSTR-3B for that period. Anything corrected in GSTR-1A flows into the same period's GSTR-3B and into the recipient's GSTR-2B, so a mistake spotted on the 15th can still be fixed cleanly. The one thing GSTR-1A cannot change is the recipient's GSTIN on a B2B invoice.

Tables 9 and 10 of a subsequent GSTR-1 are the older route, used once GSTR-3B has been filed. The correction appears in the later period, which means your customer's credit moves to the later period too. The outer limit under Section 37(3) is 30 November following the end of the financial year to which the invoice relates, or the date of filing the annual return for that year, whichever is earlier. An FY 2025-26 invoice therefore has to be amended by 30 November 2026 at the latest, and an FY 2026-27 invoice by 30 November 2027.

Late fees, sequential filing and the three-year bar

Late fee. Section 47 prescribes the fee; the operative rates come from the waiver notifications and currently run at ₹50 per day of delay (₹25 CGST plus ₹25 SGST), or ₹20 per day for a nil return, subject to a cap that depends on turnover — commonly ₹500 for nil returns, ₹2,000 up to ₹1.5 crore annual aggregate turnover, ₹5,000 between ₹1.5 crore and ₹5 crore, and ₹10,000 above ₹5 crore. These caps have been revised by Council recommendation more than once, so check the current notification before relying on a figure. The GSTR-1 late fee is collected through your next GSTR-3B rather than separately. There is no interest on a late GSTR-1, because no tax is paid through it — but see below.

Sequential filing. You cannot file GSTR-1 for a period while the previous period's GSTR-1 is outstanding, and you cannot file GSTR-1 if the preceding period's GSTR-3B has not been filed. A single skipped month therefore blocks everything after it, which is how small backlogs become large ones.

The three-year bar. Following the Finance Act 2023 amendments and their technical enforcement on the portal from the July 2025 tax period, GSTR-1 cannot be filed more than three years after its original due date. This is a permanent, system-level block with no appeal route back into the portal — a genuinely different animal from a late fee.

The errors that cost your customers their ITC

• Reporting a B2B invoice in Table 7. A registered buyer's invoice dropped into the consolidated B2C table never reaches their IMS at all. It is the single most damaging classification error in the return.
• A stale or wrong recipient GSTIN. Validate at master-data level, not at filing time. Our GST verification API exists largely because customers were doing this check by hand across thousands of vendor and customer records.
• Wrong place of supply on inter-state B2C. It misallocates revenue between states and produces a mismatch in Table 3.2 of GSTR-3B. The state code list is the reference.
• Missing the ₹1 lakh B2C large cut-off. Systems still configured for the old ₹2.5 lakh threshold under-report Table 5.
• Skipping Table 13. Document series gaps are among the easiest things for the department to query.
• Treating a nil period as nothing to do. The nil return is mandatory and can be filed by SMS in under a minute.
• Reporting the e-way bill and the invoice differently. Where e-invoicing applies, GSTR-1 is auto-populated from the IRN, and manual edits that diverge from the reported e-invoice or the linked e-way bill surface as a mismatch later.

Frequently asked questions