GSTR-1 and IFF Due Dates for October 2026: Monthly vs QRMP Filers

Oct 26

6 min read

Updated: 3 days ago

For the October 2026 tax period, a monthly GST filer must furnish GSTR-1 by Wednesday 11 November 2026. A taxpayer under the QRMP scheme has no GSTR-1 due for October; instead it may, if it wishes, upload B2B invoices through the Invoice Furnishing Facility (IFF) between 1 and 13 November 2026, and will file the quarterly GSTR-1 for October to December 2026 by 13 January 2027.

This post sets out those dates, the legal basis for each, two worked examples, and the points that commonly go wrong in the first month of a quarter: the IFF value limit, the GSTR-1A correction window, late fee and the three-year time bar. For the GSTR-3B side of the same cycle, see GST Return Due Dates October 2026: GSTR-3B Deadlines for Monthly and QRMP Filers.

Is there any extension for October 2026 GSTR-1?

As of 26 October 2026, no CBIC notification extends the GSTR-1 or IFF due date for October 2026. On 22 October 2026 the Malad Chamber of Tax Consultants, Mumbai, submitted a representation to the CBIC Chairman asking for the October GSTR-1 date to be moved from 11 to 13 November 2026, citing the Diwali holidays and portal load. A representation is only a request. Until a notification is issued under the proviso to Section 37(1), plan for 11 November 2026.

Neither 11 November (Wednesday) nor 13 November 2026 (Friday) falls on a weekend. GST due dates do not move automatically for holidays, and late fee under Section 47 runs from the day after the due date.

GSTR-1 and IFF due dates for October 2026 timeline: IFF opens 1 Nov, monthly GSTR-1 due 11 Nov, IFF closes 13 Nov, GSTR-2B on 14 Nov, quarterly GSTR-1 due 13 Jan 2027

October 2026 GSTR-1 and IFF dates at a glance

Monthly GSTR-1 for October 2026: 11 November 2026 (Section 37(1) read with Rule 59(1), CGST Rules; dates set by Notification 83/2020-Central Tax dated 10 November 2020).
IFF for October 2026 (QRMP, optional): 1 to 13 November 2026 (Rule 59(2)).
Quarterly GSTR-1 for October to December 2026 (QRMP): 13 January 2027.
GSTR-2B for October 2026: generated on 14 November 2026, reflecting GSTR-1 and IFF filed by the cut-off.
Related GSTR-3B dates: monthly GSTR-3B for October is due 20 November 2026; QRMP taxpayers pay tax for October through PMT-06 by 25 November 2026 and file no GSTR-3B for October.

Practice guide for professionals

For a table-by-table working reference on the annual return and reconciliation statement, see the GSTR-9 & GSTR-9C Practical Working Guide (PDF, ₹299).

See all guides and toolkits

Why QRMP taxpayers have no GSTR-1 for October

The QRMP scheme, notified by Notification 84/2020-Central Tax dated 10 November 2020 and operated through Rule 61A, lets registered persons with aggregate turnover up to ₹5 crore in the preceding financial year file GSTR-1 and GSTR-3B quarterly while paying tax monthly. October is month 1 of the October to December quarter, so a QRMP taxpayer files no return statement for October. The only thing it can do for October GSTR-1 purposes is use IFF.

For eligibility, opting in and out, and the fixed-sum and self-assessment payment methods, see QRMP Scheme Explained: Eligibility, Monthly Payments and Quarterly GST Returns.

How IFF works for month 1 of the quarter

IFF is optional. It exists so that B2B customers of a QRMP supplier get input tax credit in the month of supply instead of waiting for the quarterly GSTR-1.
Only B2B invoices and related debit and credit notes go in IFF. B2C supplies, exports summary tables and HSN summary are reported in the quarterly GSTR-1.
The total value of invoices furnished in IFF cannot exceed ₹50 lakh for the month (Rule 59(2)). Invoices beyond that go in the quarterly GSTR-1.
The IFF window for October runs from 1 to 13 November 2026. There is no late fee for IFF because it is optional; once the window closes, October invoices not uploaded are simply reported in the quarterly GSTR-1 by 13 January 2027.
Invoices filed in IFF by 13 November appear in the recipient's GSTR-2B for October, generated on 14 November.

GSTR-1 October 2026 monthly filer vs QRMP filer comparison: due date 11 Nov 2026 vs IFF window 1-13 Nov 2026, ₹50 lakh IFF limit, late fee and GSTR-3B or PMT-06 dates

Example 1: monthly filer

Shree Traders, Ahmedabad, has aggregate turnover of ₹9 crore and must file monthly. In October 2026 it issues 420 B2B invoices and makes some B2C sales.

GSTR-1 for October 2026 is due on 11 November 2026, with B2B, B2C, credit notes, HSN summary and document summary.
Its customers see these invoices in their October GSTR-2B on 14 November 2026, and Shree Traders' own GSTR-3B liability for October is auto-populated from this GSTR-1.
If Shree Traders files on 14 November 2026, the delay is 3 days. At ₹50 per day (₹25 CGST and ₹25 SGST), the late fee is ₹150, well within the cap for its turnover.
GSTR-3B for October is due on 20 November 2026.

Example 2: QRMP filer using IFF

Kavya Packaging, Surat, has aggregate turnover of ₹3.2 crore in FY 2025-26 and has opted for QRMP. In October 2026 it raises B2B invoices of ₹42 lakh to registered buyers and B2C sales of ₹6 lakh.

It uploads the ₹42 lakh of B2B invoices in IFF between 1 and 13 November 2026, within the ₹50 lakh limit. Its buyers can claim the credit in their October returns.
The ₹6 lakh of B2C sales are not reported in IFF; they go in the quarterly GSTR-1.
It pays October tax through PMT-06 by 25 November 2026 and files no GSTR-3B for October.
The quarterly GSTR-1 for October to December 2026, due 13 January 2027, picks up the IFF invoices already filed and adds the remaining supplies for the quarter, including all December B2B invoices (month 3 has no IFF).
If B2B invoices for October had been ₹58 lakh, only invoices up to ₹50 lakh could go in IFF; the rest would be reported in the quarterly GSTR-1, and those buyers would get the credit later.

Correcting GSTR-1: GSTR-1A and the locked GSTR-3B liability

Rule 59(4A), inserted by Notification 12/2024-Central Tax dated 10 July 2024, provides Form GSTR-1A to add or amend details of the same tax period after filing GSTR-1 but before filing GSTR-3B. For QRMP taxpayers, GSTR-1A is available for the quarter, after the quarterly GSTR-1; it is not available for an IFF month.

This matters because, under GSTN's advisory of 7 June 2025, the outward tax liability auto-populated in GSTR-3B from GSTR-1, GSTR-1A and IFF became non-editable from the July 2025 tax period. Table 3.2 values were made non-editable from the November 2025 tax period. A monthly filer that finds an error in its October GSTR-1 must therefore correct it through GSTR-1A before filing the October GSTR-3B, or through GSTR-1 of a later period. See GSTR-1A in 2026: How to Correct GSTR-1 Before Filing GSTR-3B.

Late fee, filing sequence and the three-year time bar

Late fee: Section 47(1) provides ₹100 per day (₹50 CGST and ₹50 SGST). Notification 20/2021-Central Tax dated 1 June 2021 reduced this to ₹50 per day (₹20 per day for nil returns) and capped the total at ₹500 for nil returns, ₹2,000 for turnover up to ₹1.5 crore, ₹5,000 for turnover above ₹1.5 crore and up to ₹5 crore, and ₹10,000 above ₹5 crore (CGST and SGST combined). Late fee applies to monthly and quarterly GSTR-1, not to IFF.
Filing sequence: under Rule 59(6), GSTR-1 cannot be filed if GSTR-3B for the preceding tax period has not been furnished. A monthly filer that has not filed September 2026 GSTR-3B will be blocked from filing October GSTR-1.
Three-year time bar: Section 37(5), inserted by the Finance Act, 2023 and in force from 1 October 2023, bars filing GSTR-1 after three years from its due date. GSTN has enforced this on the portal, with advisories in 2025 asking taxpayers to clear pending returns. October 2026 GSTR-1, due 11 November 2026, cannot be filed after 11 November 2029.
Mismatch control: if liability in GSTR-1 exceeds that paid in GSTR-3B beyond the prescribed limits, Rule 88C and Form DRC-01B apply. See GSTR-1 vs GSTR-3B Mismatch: DRC-01B, Rule 88C & 7-Day Response Guide.

A detailed worked calculation of late fee for delayed GSTR-1 is in GSTR-1 Late Filing: Late Fee, QRMP, IFF & ITC Impact Explained.

Checklist before 11 and 13 November 2026

Confirm whether each GSTIN is monthly or QRMP for the October to December 2026 quarter on the GST portal dashboard.
File September 2026 GSTR-3B first if it is still pending, so that Rule 59(6) does not block October GSTR-1.
Reconcile the sales register with e-invoices (IRN) auto-populated into GSTR-1 and with e-way bills.
For QRMP clients with B2B buyers who want credit in October, upload IFF by 13 November and keep it within ₹50 lakh.
Review the GSTR-3B liability draft after filing GSTR-1; use GSTR-1A before GSTR-3B if anything is wrong.
Watch the GST portal and CBIC website for any notification on the representation; until then, treat 11 November 2026 as final.

For all other November dates across GST, TDS and company law, see the November 2026 Compliance Calendar.