Knowing the exact deadline for the September 2026 GST return helps avoid late fees and interest. The due dates vary based on whether the taxpayer files monthly or quarterly under the QRMP scheme.
GSTR-3B due date for monthly filers
For taxpayers who file GSTR-3B every month, the due date for the September 2026 return is 20 October 2026. This is set out in Rule 61 of the CGST Rules, which states the return is due on or before the twentieth day of the month succeeding such month.
GSTR-3B due date for QRMP (quarterly) filers
Taxpayers under the Quarterly Return Monthly Payment (QRMP) scheme file GSTR-3B once a quarter. Since September marks the end of the second quarter (July to September), QRMP taxpayers must file their GSTR-3B in October. The due date is split into two groups based on the state where the principal place of business is registered:
Category 1 states: 22 October 2026
The deadline is the 22nd of the month following the quarter for taxpayers in: Chhattisgarh, Madhya Pradesh, Gujarat, Maharashtra, Karnataka, Goa, Kerala, Tamil Nadu, Telangana, Andhra Pradesh, Daman and Diu and Dadra and Nagar Haveli, Puducherry, Andaman and Nicobar Islands, and Lakshadweep.
Category 2 states: 24 October 2026
The deadline is the 24th of the month following the quarter for taxpayers in: Himachal Pradesh, Punjab, Uttarakhand, Haryana, Rajasthan, Uttar Pradesh, Bihar, Sikkim, Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura, Meghalaya, Assam, West Bengal, Jharkhand, Odisha, Jammu and Kashmir, Ladakh, Chandigarh, and Delhi.
GSTR-2B generation and reconciliation
Before filing GSTR-3B, taxpayers must reconcile their purchase register with GSTR-2B to claim the correct Input Tax Credit (ITC). The GST portal generates the GSTR-2B statement on the 14th of every month. For the September return, the GSTR-2B will be available on 14 October 2026.
The window between the 14th (when GSTR-2B is generated) and the 20th (the GSTR-3B due date) is tight. Finding mismatched or missing invoices quickly is necessary to contact suppliers before the deadline.
Speed up your ITC reconciliation
Use our free GSTR-2B reconciliation tool to instantly compare your purchase register with the GSTR-2B JSON. It runs completely in your browser. Your GSTR-2B and purchase register files are read in your browser and never uploaded to any server.
Late fees and interest for missed deadlines
Missing the GSTR-3B due date attracts a late fee of ₹50 per day (₹25 CGST + ₹25 SGST) of delay. For nil returns, the late fee is ₹20 per day (₹10 CGST + ₹10 SGST). The fee is capped. Under Section 47 and Notification 19/2021-Central Tax, the total for one return stops at ₹500 for a nil return, ₹2,000 if last year's turnover was up to ₹1.5 crore, ₹5,000 for turnover above ₹1.5 crore and up to ₹5 crore, and ₹10,000 above that (CGST and SGST together). On top of the late fee, interest at 18% per annum runs on the tax paid late in cash, from the day after the due date until the day of payment.
Example: a monthly filer with ₹3 crore turnover files the September 2026 GSTR-3B on 30 October 2026, ten days late. The late fee is 10 × ₹50 = ₹500, well under the ₹5,000 cap. The portal adds it to Table 5.1 of the next return, and it can only be paid from the cash ledger.
Summary of October 2026 GST due dates
| Return | Taxpayer Type | Due Date |
|---|---|---|
| GSTR-1 | Monthly filers | 11 October 2026 |
| GSTR-1 (July to September quarter) | QRMP filers | 13 October 2026 |
| GSTR-3B | Monthly filers | 20 October 2026 |
| GSTR-3B | QRMP filers (Category 1) | 22 October 2026 |
| GSTR-3B | QRMP filers (Category 2) | 24 October 2026 |
What to do once GSTR-2B is generated
Once GSTR-2B appears on the 14th, match it against your purchase register before preparing GSTR-3B. Spotting missing invoices, rate errors, and unfiled vendor returns early protects your input tax credit and prevents DRC-01C mismatch notices.
There is no IFF in October for quarterly filers: the facility covers only the first two months of a quarter, and September is the third. The quarter's invoices go in the quarterly GSTR-1 due on 13 October.
Next up: the November 2026 dates
If you landed here after 20 October, these are the dates for the October 2026 tax period:
- 11 November 2026: GSTR-1 for monthly filers.
- 13 November 2026: optional IFF for quarterly filers (October B2B invoices).
- 14 November 2026 (a Saturday): GSTR-2B for October is generated.
- 20 November 2026: GSTR-3B for monthly filers.
- 25 November 2026: PMT-06 tax payment for quarterly filers. They file no GSTR-3B in November.
The full monthly calendar, with the six-day matching window, is in GSTR-2B due date and generation timeline. GSTR-1 dates and fees are in GSTR-1 due dates.
Match before you file
Load your GSTR-2B (Excel or JSON) and purchase register into the free gstr2bmatch.in tool. It lists missing invoices and the ITC at risk in a few minutes, and your files never leave your browser.
Frequently asked questions
When is the GSTR-3B due date for September 2026?
For monthly filers, the due date is 20 October 2026. For quarterly (QRMP) filers, the due date is 22 or 24 October 2026, depending on the principal place of business.
Are there different due dates for QRMP filers?
Yes. Quarterly return filers have their GSTR-3B due dates split into two groups by State: either the 22nd or the 24th of the month following the quarter.
Last checked: 21 October 2026
Sources: GST Portal User Guide (GSTR-3B), CGST Rules, GSTN IFF FAQ, GSTN QRMP manual, GSTN GSTR-3B filing manual