GSTR-1 Filing: A Complete Step-by-Step Guide for 2026

What is GSTR-1?

GSTR-1 is a monthly or quarterly return that captures the details of all outward supplies of goods and services — in plain terms, everything you sold. It is a statement of your sales invoices, credit and debit notes, exports, and advances received during the tax period.

GSTR-1 is filed at the invoice level for most B2B transactions, which is what makes it so consequential. The data you report here is the source from which your buyers claim their input tax credit (ITC). When you upload a B2B invoice in your GSTR-1, it shows up in your customer's GSTR-2B, allowing them to claim the GST you charged them.

• It is a return of outward supplies (sales), not purchases.
• Most B2B supplies are reported invoice-by-invoice.
• B2C and certain other supplies are reported in consolidated, rate-wise summaries.
• It is the foundation of the ITC chain for your buyers.

Who has to file GSTR-1, and how often?

Every normal GST-registered taxpayer must file GSTR-1, even if there were no sales in the period (a nil return). A few categories are exempt — composition scheme dealers (who file CMP-08 and GSTR-4 instead), input service distributors, non-resident taxable persons, and those deducting or collecting tax at source — but the vast majority of regular businesses are in scope.

How often you file depends on your turnover. Businesses with an aggregate annual turnover above ₹5 crore must file monthly. Businesses with turnover up to ₹5 crore can opt into the QRMP scheme — Quarterly Return, Monthly Payment — and file GSTR-1 quarterly while still paying tax every month.

• Monthly filers: aggregate turnover above ₹5 crore (mandatory).
• Quarterly filers (QRMP): turnover up to ₹5 crore, who opt in.
• QRMP filers pay tax monthly via challan but file the GSTR-1 return quarterly.
• Composition dealers, ISDs, NRTPs, and TDS/TCS deductors do not file GSTR-1.

GSTR-1 due dates for 2026

Missing a due date is the single most avoidable GSTR-1 error, so it is worth committing these to memory. For monthly filers, GSTR-1 is due on the 11th of the month following the tax period — for example, the January 2026 return is due 11th February 2026.

For QRMP (quarterly) filers, the GSTR-1 return is due on the 13th of the month following the end of the quarter. To make sure buyers can still claim credit on a timely basis, QRMP taxpayers can use the Invoice Furnishing Facility (IFF) to upload B2B invoices for the first two months of the quarter, optionally, by the 13th of the following month.

• Monthly GSTR-1: 11th of the next month.
• Quarterly GSTR-1 (QRMP): 13th of the month after the quarter ends.
• IFF (optional, QRMP only): B2B invoices for month 1 and month 2 of the quarter, due 13th of the next month.
• Always check the portal for any CBIC due-date extensions before filing.

How GSTR-1, GSTR-2B and GSTR-3B fit together

These three returns work as a connected system, and understanding the flow makes compliance far easier. GSTR-1 is your outward-supply statement. When you file it, the GST system uses that data to auto-generate GSTR-2B for each of your buyers — a static, monthly statement of the ITC available to them based on what their suppliers (including you) reported.

GSTR-3B is the monthly summary return where tax is actually paid. It pulls your outward liability (which should tie back to GSTR-1) and your eligible ITC (which should tie back to GSTR-2B). In short: GSTR-1 feeds your buyer's GSTR-2B, and both GSTR-1 and GSTR-2B should reconcile with the figures in your GSTR-3B.

• GSTR-1 (you) generates GSTR-2B (your buyer's ITC statement).
• GSTR-3B is the summary and payment return — file GSTR-1 first.
• Your GSTR-1 outward tax should match the liability you declare in GSTR-3B.
• A mismatch between GSTR-1 and GSTR-3B is a top trigger for department notices.

The main tables in GSTR-1 explained

GSTR-1 is organised into numbered tables, each capturing a specific kind of supply. You do not need to fill every table — only those that apply to your business — but you should know what each one is for so nothing slips through.

• Table 4A / 4B (B2B): Registered-buyer supplies, reported invoice-by-invoice. Table 4B covers supplies attracting reverse charge.
• Table 5 (B2C Large): Inter-state supplies to unregistered persons where the invoice value exceeds ₹2.5 lakh, reported invoice-wise.
• Table 6A (Exports): Export invoices, with or without payment of IGST, plus shipping bill details.
• Table 7 (B2C Small): All other supplies to unregistered persons, reported as a consolidated, rate-wise and state-wise summary.
• Table 9B (Credit / Debit Notes): Notes issued against earlier invoices, for registered and unregistered recipients.
• Table 11 (Advances): Tax on advances received and adjustment of advances against invoices.
• Table 12 (HSN Summary): A rate-wise summary of supplies by HSN/SAC code — now mandatory and increasingly validated on the portal.
• Table 13 (Documents Issued): A count of invoices, debit notes, credit notes and other documents issued, used and cancelled in the period.

How to file GSTR-1 on the GST portal: step by step

Filing on the government portal follows a consistent sequence. Whether you key in invoices manually or upload a JSON file generated by your accounting software, the broad steps are the same.

1. 1Log in to the GST portal at gst.gov.in with your credentials and go to Services, then Returns, then Returns Dashboard.
2. 2Select the financial year and the tax period (month or quarter) you are filing for, and click Prepare Online — or choose offline/JSON upload.
3. 3Enter your outward supplies table by table — B2B, B2C, exports, credit/debit notes, advances, HSN summary — or upload the JSON file generated by your billing software.
4. 4Click Generate GSTR-1 Summary so the portal consolidates and validates all the data you have entered or uploaded.
5. 5Open the Preview, download the draft, and carefully check totals, place of supply, GSTINs and HSN figures against your books.
6. 6Click Submit to freeze the data (after this, no further edits are allowed for the period), then File the return using a Digital Signature Certificate (DSC) or Electronic Verification Code (EVC).
7. 7Download the filed return and the acknowledgement (ARN) for your records.

Common GSTR-1 mistakes and how to avoid them

Most GSTR-1 problems are not exotic — they are the same handful of avoidable errors repeated across thousands of returns. Knowing them in advance is half the battle.

• Wrong place of supply (POS): Picking the wrong state turns an intra-state supply into inter-state (or vice versa), causing CGST/SGST vs IGST errors. Always set POS from the buyer's delivery location.
• Missing or incorrect HSN summary: Table 12 is mandatory and validated; skipping it or using vague codes leads to errors and notices.
• B2B vs B2C misclassification: Reporting a registered buyer's invoice under B2C means they cannot see it in GSTR-2B and lose their ITC. Always verify and enter the buyer's GSTIN.
• GSTR-1 vs GSTR-3B mismatch: Outward liability in GSTR-1 must match GSTR-3B; differences invite scrutiny and reconciliation notices.
• Late filing: The late fee is ₹50 per day (₹25 CGST + ₹25 SGST) for returns with liability, and ₹20 per day (₹10 + ₹10) for nil returns, subject to caps. Interest at 18% per annum can also apply on delayed tax through GSTR-3B.
• Forgetting amendments: Errors in a filed GSTR-1 cannot be edited directly — they must be corrected via amendment tables in a subsequent period's return.

How Dribble Books automates GSTR-1

If filing GSTR-1 by hand feels error-prone, that is because it is. Dribble Books is built to take the manual effort — and the guesswork — out of the entire process. Because your sales invoices already live in Dribble Books, the software does the heavy lifting of turning them into a return.

When it is time to file, Dribble Books automatically compiles every invoice, credit note and debit note for the period into the correct GSTR-1 tables, classifies B2B and B2C supplies, derives the place of supply, and builds the HSN summary for you. You review a clean, ready-to-file summary instead of stitching together spreadsheets.

• Auto-compiles your invoices into the exact GSTR-1 table structure (B2B, B2C, exports, notes, advances).
• Generates the Table 12 HSN/SAC summary automatically from your line items.
• Exports a portal-ready JSON file you can upload directly to gst.gov.in.
• Flags reconciliation gaps so your GSTR-1 and GSTR-3B figures stay in sync.
• Supports both monthly and QRMP/IFF workflows, with due-date reminders so you never miss a filing.

Final thoughts

GSTR-1 does not have to be stressful. Once you understand that it is simply a structured statement of your sales — and that it directly powers your buyers' input tax credit — the discipline that matters most is accuracy and timeliness. Classify supplies correctly, keep your HSN summary clean, reconcile against GSTR-3B, and never miss the 11th (monthly) or 13th (quarterly) deadline.

Better still, let your software carry the load. If you would rather stop wrestling with tables and JSON files, Dribble Books can compile, validate and export your GSTR-1 in minutes — so you can focus on running your business instead of decoding the portal. Try it for your next filing period and feel the difference.