GSTR-3B Due 20 October 2026: September + Q2 Deadlines, ITC Checklist & Late-Filing Risks

The Deadlines: 20, 22 and 24 October

October 2026 has three ordinary GSTR-3B deadlines, depending on how you file. Under Section 39 of the CGST Act read with Rule 61, the monthly return is due by the 20th of the succeeding month — so the September 2026 GSTR-3B falls due on 20 October 2026 for regular monthly filers. Taxpayers under the QRMP scheme file one GSTR-3B for the July–September 2026 quarter on a state-specific date: 22 October 2026 (Group A states) or 24 October 2026 (Group B states).

QRMP (Quarterly Return, Monthly Payment) is open to taxpayers with aggregate turnover up to ₹5 crore in the preceding financial year; they pay tax monthly through Form PMT-06 (by the 25th of the first two months of the quarter) and file GSTR-3B quarterly. Group A states include Gujarat, Maharashtra, Karnataka, Kerala, Tamil Nadu, Telangana, Andhra Pradesh, Madhya Pradesh, Chhattisgarh, Goa, Puducherry, Daman & Diu, Dadra & Nagar Haveli, and the Andaman & Nicobar and Lakshadweep islands. Group B states include Delhi, Haryana, Punjab, UP, Rajasthan, Bihar, West Bengal, Odisha, Jharkhand, the North-East, Himachal Pradesh, Uttarakhand, J&K, Ladakh and Chandigarh.

One practical warning: the statutory date is not extended automatically just because 20 October is a public holiday (Dussehra) or because the portal is slow. An extension needs an actual notification. Confirm your own category’s date on the GST portal return dashboard before you assume anything.

Pre-Filing ITC Checklist: Run These Checks First

GSTR-3B is where output tax is paid and input tax credit (ITC) is claimed — and it is also where most notices begin. Run this checklist before you hit submit:

1. Match GSTR-1 with Table 3.1. The outward-supply figures in your GSTR-3B must reconcile with the September GSTR-1 (filed 11 October for monthly filers). Mismatches generate an auto-comparison visible to the jurisdictional officer — no manual intervention needed on their side.
2. Reconcile GSTR-2B with Table 4. GSTR-2B for September was generated on 14 October 2026. Claim ITC only on what reflects in your 2B. Remember the pattern the department is watching now: taxpayers who set off their entire liability against ITC with zero cash payment are flagged for granular analysis (per the Centre-State review reported 13 October 2026).
3. Handle reverse-charge (RCM) entries. RCM tax goes in Table 3.1(d) and the ITC, where eligible, in Table 4 — and RCM must be paid in cash, not through the credit ledger.
4. Reverse ineligible ITC. Personal use, exempt-supply-related credit, and blocked credits (motor vehicles, food and beverages for own consumption, etc.) must be reversed in Table 4B.
5. Verify e-invoice QR/IRN data. For taxpayers with turnover above ₹5 crore, e-invoicing is mandatory — make sure invoiced turnover matches reported turnover.
6. Check the HSN summary. Report HSN-wise outward supplies as required; errors here feed into the annual GSTR-9 reconciliation pain later.

The Cost of Filing Late

Missing the date is expensive, and the meter runs daily:

• Late fee: ₹100 per day of delay (CGST + SGST), capped at ₹5,000. Reduced late fees apply to nil returns and certain small taxpayers — but “small” does not mean free.
• Interest: 18% per annum on the net cash tax liability for the delay period. On a ₹5 lakh monthly liability delayed 15 days, that is roughly ₹3,700 — and it compounds the longer you wait.
• Notice risk: Persistent late or non-filing invites scrutiny. The compliance-reset mood of the 57th GST Council (see our 57th GST Council decisions article) is business-friendly, but it is paired with sharper data analytics — not a free pass.

Quarterly QRMP filers should note that while the 3B itself is quarterly, tax payment via PMT-06 is monthly — a missed monthly payment still attracts interest even if the return is on time.

Why This Filing Matters More Than Usual

This is not just another monthly return. September’s 3B is the last monthly return of the July–September quarter — and the quarter-end figures feed directly into your GSTR-9 annual return reconciliation. ITC claimed in October for FY 2025-26 invoices is also running against the 30 November time limit for claiming prior-year credit (Section 16(4)). Cleaning up reconciliation now saves a painful December.

For every upcoming GST, income-tax and TDS date in one place, bookmark our Compliance Calendar Hub and the GST Hub for rates, registration and return guides. If the filing feels beyond DIY, our GST consultant service handles monthly returns and notices end-to-end.

Frequently Asked Questions

What is the GSTR-3B due date for September 2026?

20 October 2026 for regular monthly filers. QRMP quarterly filers for July–September 2026 file on 22 October (Group A states) or 24 October (Group B states), depending on the state of principal place of business.

Is the GSTR-3B date extended because 20 October is Dussehra?

Not automatically. The statutory date stands unless an actual notification extends it. Do not assume a holiday extension — verify on the GST portal dashboard and file by 20 October to be safe.

What is the late fee for a delayed GSTR-3B?

₹100 per day (CGST + SGST), capped at ₹5,000, plus 18% per annum interest on the net cash tax liability for the delay period. Reduced late fees apply to nil returns and small taxpayers.

Can I claim ITC not reflecting in GSTR-2B?

No. ITC must be claimed only against inward supplies reflecting in your GSTR-2B (generated 14 October for September). Claiming beyond 2B is the fastest route to a mismatch notice.

I’m on QRMP — do I need to do anything monthly?

Yes. QRMP filers pay tax monthly through Form PMT-06 (by the 25th of the first two months of the quarter) and can furnish IFF for the first two months; the GSTR-3B itself is filed quarterly.