GST Returns in One Minute
If you are GST-registered, you file returns that tell the government what you sold, what you bought, and how much tax you owe. For most small businesses the two that matter every month are GSTR-1 (your outward sales) and GSTR-3B (your summary return and tax payment). File both on time, pay the tax, and you are compliant. Everything below is detail around those two.
GSTR-1: Your Sales Return
GSTR-1 reports every outward supply — your invoices — for the period. It is what lets your B2B customers claim input tax credit (ITC), so filing it correctly and on time matters to your customers as much as to you.
- What goes in: B2B invoices (with customer GSTIN), B2C summaries, credit and debit notes, exports, and advances.
- Frequency: Monthly for most; quarterly under the QRMP scheme if your turnover is up to Rs 5 crore.
- Why accuracy matters: Your GSTR-1 auto-populates your customers' GSTR-2B and your own GSTR-3B. Errors here ripple everywhere.
If your invoices are raised in software, GSTR-1 is largely an export — see how to create a compliant GST invoice so the data is right at source.
GSTR-3B: Your Summary Return and Payment
GSTR-3B is the monthly (or quarterly) summary where you declare total sales, total ITC claimed, and pay the net tax. Since 2026 it arrives largely auto-populated from your GSTR-1 and your suppliers' filings, and the ITC figure is increasingly locked to what your suppliers have actually reported.
- Output tax: Pulled from your GSTR-1.
- Input tax credit: Pulled from GSTR-2B — you can claim only what suppliers have filed.
- Net payable: Output tax minus eligible ITC, paid via cash or credit ledger.
Because ITC is now hard-tied to supplier filings, monthly reconciliation is essential — read our GSTR-2A reconciliation guide and the deeper GSTR-3B auto-population walkthrough.
The Other Returns You Might Meet
- GSTR-2B: A static, auto-drafted statement of your available ITC. You do not file it — you reconcile against it.
- GSTR-9: Annual return, consolidating the year. Mandatory above a turnover threshold; watch for auto late fees.
- CMP-08 / GSTR-4: For composition-scheme dealers.
Due Dates to Remember
- GSTR-1 (monthly): 11th of the following month.
- GSTR-1 (QRMP, quarterly): 13th of the month after the quarter.
- GSTR-3B (monthly): 20th of the following month.
- GSTR-3B (QRMP): 22nd or 24th, depending on your state.
- GSTR-9 (annual): 31 December of the next financial year.
Late filing attracts a per-day late fee plus interest on unpaid tax, and it blocks your customers' ITC — so treat these dates as hard deadlines.
The QRMP Scheme (for turnover up to Rs 5 crore)
QRMP lets smaller businesses file GSTR-1 and GSTR-3B quarterly while paying tax monthly via a simple challan (PMT-06). It cuts filing frequency from 24 returns a year to a much lighter load. If you qualify and your compliance is straightforward, it is usually worth opting in.
Common Filing Mistakes
- Claiming more ITC than appears in GSTR-2B — now auto-blocked and reversible with interest.
- Mismatched figures between GSTR-1 and GSTR-3B — a top scrutiny trigger.
- Forgetting credit and debit notes, understating or overstating turnover.
- Missing the due date and stacking late fees, especially on GSTR-9.
How Software Makes This Painless
The whole cycle gets far simpler when your billing and returns share the same data. InfiBis generates GST-compliant invoices, prepares GSTR-1 exports, and keeps your sales and purchase records reconciled so GSTR-3B is a review-and-file rather than a rebuild-from-scratch exercise.
Conclusion
GST filing sounds intimidating but reduces to a rhythm: file GSTR-1 by the 11th, reconcile your ITC, file and pay GSTR-3B by the 20th, and handle GSTR-9 once a year. Keep clean invoice data, reconcile monthly, and never miss a due date. For the compliance changes that reshaped filing in 2026, see our 1 April 2026 checklist.