How to file GSTR-1, step by step

Arthora Guides · Updated August 2026 · 8 min read

GSTR-1 is the return where you tell the government about every sale you made. It is also the return your buyers care about most — what you file here lands in their GSTR-2B, and a mistake on your side blocks the input tax credit on theirs. Here is the whole process, in the order you actually do it.

What GSTR-1 is

GSTR-1 is the monthly (or quarterly) statement of outward supplies — your sales invoices, credit notes, debit notes and exports — filed by every regular GST-registered business. It carries no tax payment; the tax is paid with GSTR-3B. GSTR-1's job is detail: invoice by invoice, so that the system can show each of your buyers their purchases.

When it is due

Under QRMP, the first two months of a quarter have an optional IFF (Invoice Furnishing Facility, by the 13th) — use it to upload your B2B invoices monthly so your buyers do not wait a whole quarter for their credit. Good sellers use it; buyers notice.

The tables that matter

The portal shows a dozen-plus tables, but a typical business touches these:

• Table 4 — B2B invoices. Every sale to a GST-registered buyer, invoice by invoice, with the buyer's GSTIN. This is the table that feeds their 2B — get GSTINs and invoice numbers exactly right.
• Table 5 — B2C (Large). Inter-state sales to consumers above ₹2.5 lakh per invoice, invoice-wise.
• Table 7 — B2C (Others). All remaining consumer sales, summarised by state and rate.
• Table 6 — Exports and SEZ supplies, with or without payment of tax, shipping bill details if claiming refund.
• Table 9 — Amendments. Corrections to invoices you reported in earlier periods, and credit/debit notes against them.
• Table 12 — HSN summary. Sales grouped by HSN code — 4-digit codes if your turnover is up to ₹5 crore, 6-digit above it.
• Table 13 — Documents issued. The serial-number ranges of invoices, credit notes and challans you used and cancelled this period.

Step by step

1. Close the period in your books first. Every sales invoice, credit note and export for the month should be entered and numbered before you start. Filing from a half-entered book is how amendments are born.
2. Build the return from the books, not from memory. Group B2B invoice-wise, B2C rate-wise, prepare the HSN and document summaries. (This is exactly the step software should do for you — see below.)
3. Reconcile the totals. The taxable value in GSTR-1 should equal your sales register for the period. If e-invoicing applies to you, the IRP-reported invoices auto-populate into GSTR-1 — check them against your register rather than trusting blindly.
4. Upload on the portal. Use the offline utility / JSON upload for volume, or direct entry for a handful of invoices. Fix validation errors (wrong GSTIN format, duplicate invoice numbers) before submitting.
5. Verify and file with DSC or Aadhaar EVC. Once filed, GSTR-1 cannot be revised — corrections go through Table 9 next period.
6. Tell your 3B. The liability you declared here flows to GSTR-3B. If you use the portal's auto-drafted 3B, confirm the figures match your books before paying.

Late fees and what a delay really costs

The statutory late fee runs per day of delay (₹50/day for a normal return, ₹20/day for a nil return, with turnover-linked caps). But the real cost is commercial: your buyer's 2B for the month is generated on the 14th — file after that and their credit slips a month, and a buyer whose credit you delay twice starts asking their other vendors for quotes.