Every regular taxpayer reporting outward supplies must track both the regular monthly schedule and the statutory year-end cut-offs. Missing the regular due dates pushes outward tax details into the next period and delays your buyers from taking credit in their monthly GSTR-2B. For more details on delayed submissions, check our guide on GSTR-1 late fee and due dates.
GSTR-1 and IFF calendar for November 2026
The dates for outward supply filings in November 2026 depend on whether you file monthly or quarterly under the CGST Rules:
- Monthly GSTR-1 (October 2026 tax period): Due on 11 November 2026 as specified on the GST Portal GSTR-1 Guide.
- Quarterly IFF (October 2026 supplies, QRMP scheme): Due on 13 November 2026 under Rule 59 of the CGST Rules.
Common mistake: Assuming that quarterly filers can upload all October invoices at the quarter end in January without consequence. If you do not upload B2B invoices in the IFF by 13 November 2026, your buyers cannot view them in their October GSTR-2B generated on 14 November, blocking their timely credit.
Why November 2026 is the final deadline for FY 2025-26 changes
Filing in November 2026 is not just a standard monthly return. It serves as the final cut-off date for corrections relating to the previous financial year (FY 2025-26).
Under the proviso to Section 37(3) of the CGST Act, no rectification of error or omission in details of outward supplies is allowed after the 30th day of November following the end of the financial year, or the actual date of filing the relevant annual return, whichever is earlier.
Similarly, for credit notes, Section 34(2) of the CGST Act mandates that any registered person issuing a credit note must declare it in the return for the month during which it was issued, but not later than 30 November following the end of the financial year in which the supply occurred, or the annual return filing date, whichever is earlier.
Permanent tax loss: If a supplier fails to upload a credit note for FY 2025-26 by 30 November 2026, the law disallows reducing the outward tax liability. The excess tax previously deposited becomes unadjustable through regular GST returns.
Worked example: credit note adjustment before 30 November
Consider an enterprise, Bharat Engineering Works, that supplied machinery in January 2026 (FY 2025-26) and issued a sales return credit note in October 2026.
| Document | Taxable value | GST rate | Output tax liability | Status in November 2026 GSTR-1 |
|---|---|---|---|---|
| Original invoice INV-882 (Jan 2026) | ₹5,00,000 | 18% | ₹90,000 | Reported in FY 2025-26 |
| Credit note CN-041 (Oct 2026 return of goods) | ₹1,00,000 | 18% | -₹18,000 | Reported on 11 November 2026 |
| Net adjusted liability | ₹4,00,000 | 18% | ₹72,000 | Tax liability reduced by ₹18,000 |
Because Bharat Engineering Works entered CN-041 in its GSTR-1 filed on 11 November 2026, the reduction of ₹18,000 is allowed. If filing had been postponed past 30 November 2026, Section 34(2) would bar this adjustment permanently.
Sequential filing condition under Section 37(4)
A taxpayer cannot submit GSTR-1 for October 2026 if any previous tax period GSTR-1 remains unfiled. Under Section 37(4) of the CGST Act, sequential filing is strictly enforced on the portal. In addition, under Rule 59(6) of the CGST Rules, GSTR-1 is blocked if GSTR-3B for the preceding tax period has not been furnished.
Frequently asked questions
What is the GSTR-1 due date in November 2026 for monthly filers?
The GSTR-1 due date for monthly filers reporting October 2026 outward supplies is 11 November 2026 under Rule 59.
What is the IFF due date in November 2026 for quarterly filers?
The Invoice Furnishing Facility due date for quarterly taxpayers covering October 2026 (Month 1 of Q3) is 13 November 2026.
Can FY 2025-26 credit notes be reported after 30 November 2026?
No. Under Section 34(2) of the CGST Act, credit notes relating to FY 2025-26 supplies cannot be declared after 30 November 2026 or the date of furnishing the annual return, whichever is earlier.
Reconcile your sales and GSTR-2B locally
Ensure all your vendor invoices and outward credit notes match before filing deadlines. Your GSTR-2B and purchase register files are read in your browser and never uploaded to any server.
Last checked: 23 October 2026. Sources: CBIC Tax Repository - Section 37, GST Portal GSTR-1 User Manual.