GST Return Filing Guide: GSTR-1, GSTR-3B, GSTR-9 — Due Dates, Process and Penalties

Which Return Does Your Business File?

The return you file depends on your registration type and whether you have opted into the QRMP scheme. The main categories are regular taxpayers, composition dealers, non-resident taxable persons, Input Service Distributors and TDS/TCS deductors. This guide focuses on regular taxpayers, who make up the majority of GST filers.

For the connected rule, example or next step, see GST Annual Return GSTR-9 for SMEs: Examples, Documents and Common Mistakes.

GSTR-1: Outward Supply Details

GSTR-1 captures invoice-level details of all outward supplies (sales) made during the tax period. It feeds into your customers' GSTR-2B auto-drafted ITC statement. Inaccurate or late GSTR-1 filing directly harms your buyers' ITC claims.

For the connected rule, example or next step, see GST on Corporate Guarantees Between Group Companies: Checklist, Due Dates and Common Mistakes.

Due Dates — GSTR-1

Under QRMP, the Invoice Furnishing Facility (IFF) lets you upload B2B invoices for the first two months of the quarter by the 13th of the following month — so your buyers can claim ITC without waiting for the quarterly GSTR-1. IFF is optional; the quarterly GSTR-1 is mandatory.

GSTR-3B: Summary Return and Tax Payment

GSTR-3B is the self-assessed summary return in which you declare consolidated figures for outward supplies, inward supplies, ITC claimed and net tax payable. Tax must be paid before or at the time of filing GSTR-3B. It cannot be filed without full payment of admitted liability.

Due Dates — GSTR-3B

Category 1 and Category 2 state classification follows CBIC notifications. Check the GST portal or the latest CBIC circular for the applicable due date for your registered state.

GSTR-2B: Auto-Generated ITC Statement

GSTR-2B is a system-generated, read-only input tax credit statement available on the 14th of the month following the tax period. It shows ITC available based on your suppliers' GSTR-1, GSTR-5 and GSTR-6 filings. You cannot file or modify it — but you must reconcile it with your books before claiming ITC in GSTR-3B.

ITC mismatch between GSTR-2B and GSTR-3B can attract notices under Rule 88D. Reconcile GSTR-2B against your purchase register every month before the 20th.

The QRMP Scheme

The Quarterly Return Monthly Payment (QRMP) scheme is available to taxpayers whose aggregate annual turnover in the preceding financial year was up to ₹5 crore. It reduces compliance burden by allowing quarterly GSTR-1 and GSTR-3B filing while requiring monthly self-assessed tax payment via Form PMT-06.

GSTR-9: Annual Return

GSTR-9 is the annual return consolidating all monthly/quarterly returns filed during the financial year. It provides a bird's-eye reconciliation of outward supplies, inward supplies, ITC availed, tax paid and any adjustments. The due date is 31 December of the year following the financial year (e.g., for FY 2025-26, due by 31 December 2026).

CBIC has from time to time waived GSTR-9 for small taxpayers. Check the current year's notification for applicability. As of this writing, GSTR-9 is mandatory for taxpayers with aggregate annual turnover exceeding ₹2 crore (verify against the current year's CBIC notification before filing).

GSTR-9C: Reconciliation Statement

GSTR-9C is a self-certified reconciliation statement comparing the GSTR-9 figures with the audited financial statements. It is filed alongside GSTR-9 by taxpayers whose aggregate annual turnover exceeds ₹5 crore. There is no separate CA certification requirement since FY 2020-21; the taxpayer self-certifies the reconciliation.

GSTR-4: Annual Return for Composition Dealers

Composition dealers file GSTR-4 annually (not monthly), due by 30 April of the year following the financial year. Monthly tax payment (CMP-08) is still required by the 18th of the month following each quarter. Composition dealers cannot issue tax invoices or claim input tax credit.

GSTR-10: Final Return

A registered person whose registration is cancelled or surrendered must file GSTR-10 (Final Return) within three months of the date of cancellation order or the date of the cancellation order, whichever is later. Non-filing after notice attracts assessment by the proper officer.

Late Fee and Interest

CBIC periodically issues notifications reducing or waiving late fees for specific periods or categories of taxpayers. Always check the GST portal or the latest notification before computing late fee.

Step-by-Step: Filing GSTR-3B

1. Reconcile your sales register and purchase register with GSTR-2B (available from the 14th).
2. Compute net ITC eligible under Section 17 (exclude blocked credits under Section 17(5)).
3. Log in to the GST portal (gstin.gov.in) and navigate to Returns > Returns Dashboard.
4. Select the financial year and tax period; click Prepare Online for GSTR-3B.
5. Fill Table 3.1 (outward supplies), Table 3.2 (inter-state supplies), Table 4 (ITC) and Table 5 (exempt / non-GST supplies).
6. The portal computes tax payable in Table 6. Verify the figures and make payment via Create Challan if balance is outstanding.
7. Submit the return; OTP-verify with EVC or DSC. Once submitted, GSTR-3B cannot be revised — only future period amendments in GSTR-1 can correct outward supply errors.

Common Filing Mistakes to Avoid

• Claiming ITC beyond GSTR-2B: Rule 36(4) restricts ITC claims to amounts reflected in GSTR-2B plus a permitted tolerance. Excess claims attract reversal and interest.
• Wrong tax head (IGST vs CGST/SGST): Misclassifying inter-state vs intra-state supply leads to head-mismatch which cannot be adjusted without a proper offset mechanism.
• Not filing GSTR-1 before 3B: GSTR-1 must be filed first. Filing only 3B creates a one-sided picture and triggers Rule 88C mismatch risk.
• Forgetting reverse charge (RCM) liability: RCM supplies must be declared in GSTR-3B Table 3.1(d) and tax paid even if no forward charge liability exists that month.
• Claiming ITC on exempt supplies: ITC attributable to exempt supplies must be reversed under Rule 42/43. Failure to reverse is a common audit trigger.

Official References

All due dates, rates and procedures are derived from official sources. Verify against current CBIC notifications before acting.

• CGST Act Section 37 — Outward supply returns (GSTR-1)
• CGST Act Section 39 — Periodic returns (GSTR-3B)
• CGST Act Section 44 — Annual return (GSTR-9/9C)
• CGST Act Section 47 — Levy of late fee
• CGST Act Section 50 — Interest on delayed payment of tax
• CGST Rule 61 — Form and manner of submitting GSTR-3B