GSTR-1 for quarterly (QRMP) filers, Oct 2026: due 13 October 2026, and when to use IFF

Last updated 11 Oct 2026 · India

Last checked: 11 Oct 2026 against GST portal: GSTR-1 user guide and GST portal: IFF FAQs.

Short answer. If you are in the QRMP scheme (aggregate turnover up to ₹5 crore), your quarterly GSTR-1 for July–September 2026 is due on Tuesday 13 October 2026, in every state. In the first two months of a quarter you may also use the optional Invoice Furnishing Facility (IFF) by the 13th of the next month, so your business customers get input tax credit monthly. IFF is for B2B invoices only, is capped at ₹50 lakh of invoice value per month, has no late fee, and simply expires after the 13th (GST portal IFF FAQs). As of 13 Oct 2026 we found no notification extending 13 Oct, and no official notice moving QRMP filers to monthly GSTR-1.

“The due date to file Form GSTR-1 for a given tax period is 11th day of the succeeding month in case of taxpayers filing it monthly and 13th day of month succeeding the end of every quarter in case of taxpayers filing quarterly or such other dates as may be extended by Government through notification.”
— GST portal, Form GSTR-1 user guide (checked 13 Oct 2026)

“IFF is an optional facility provided to quarterly taxpayers only.”
— GST portal, IFF FAQs (checked 13 Oct 2026)

Why IFF exists

A quarterly filer's invoices normally reach the buyer's GSTR-2B only once a quarter. Your registered customers then wait up to three months for their input tax credit, and some prefer suppliers who file monthly. IFF (Rule 59(2) of the CGST Rules) lets you upload B2B invoices for month 1 and month 2, so they appear in the buyer's GSTR-2A/2B that month, while you still file one GSTR-1 for the quarter.

The dates for the next two quarters

What	Period	Due
GSTR-1 (quarterly)	Jul–Sep 2026	Tue 13 Oct 2026
Switch between quarterly and monthly filing for the next quarter	Oct–Dec 2026	window 1 Aug to 31 Oct 2026
IFF (optional)	Oct 2026	13 Nov 2026
IFF (optional)	Nov 2026	13 Dec 2026
GSTR-1 (quarterly)	Oct–Dec 2026	13 Jan 2027

Tax is still paid monthly in months 1 and 2 through PMT-06 by the 25th, and GSTR-3B is quarterly (22nd or 24th by state; see GSTR-3B quarterly due dates).

What goes into IFF and what doesn't

In IFF: B2B invoices (tables 4A, 4B, 4C, 6B, 6C), credit/debit notes to registered persons (9B) and their amendments (9A, 9C).
Not in IFF: B2C sales. Report them in the quarterly GSTR-1.
Invoices filed in IFF are not entered again in the quarterly GSTR-1.
If the total value of the IFF exceeds ₹50 lakh, the portal shows "Error in submission". Move some invoices to the next period.

Late fee for GSTR-1

IFF has no late fee. A late GSTR-1 does. Under Notification 20/2021-Central Tax, the total CGST late fee per return is capped at ₹250 for a nil return, ₹1,000 if last year's aggregate turnover was up to ₹1.5 crore, and ₹2,500 for ₹1.5–5 crore. States levy a matching amount under their SGST laws, so the total you pay is usually double these caps. A late GSTR-1 also delays your customers' credit, which can cost you the customer.

Returns now time out. Under sections 37(5) and 39(11) of the CGST Act, a return cannot be filed after three years from its due date. The GST portal began blocking such returns from the November 2025 tax period (GSTN advisory, 29 Oct 2025).

Did QRMP filers move to monthly GSTR-1 from July 2026? We found no official basis for it. One May 2026 blog post said IFF was withdrawn and cited "Notification 14/2026-Central Tax". When we checked on 13 Oct 2026, the ICAI index of 2026 Central Tax notifications listed only 01/2026 (21 Apr 2026, GSTR-3B for March) and 02/2026 (7 May 2026, Appellate Tribunal), with no change to GSTR-1. The GSTR-1 guide and IFF FAQs on the GST portal still describe quarterly GSTR-1 with optional IFF. Your Returns Dashboard on gst.gov.in shows the returns that apply to you.

Common mistakes

Waiting for the quarter to upload B2B invoices. If a big customer needs credit this month, use IFF by the 13th.
Submitting IFF and not filing it. A submitted IFF must be filed, or the quarterly GSTR-1 cannot be filed.
Putting B2C sales into IFF. They belong in the quarterly GSTR-1.
GSTR-1 and GSTR-3B that don't match. If GSTR-1 tax exceeds GSTR-3B tax beyond the notified limit, the portal sends DRC-01B and asks you to pay with interest or explain within 7 days (Rule 88C).
Missing the 31 Oct switch window. If you want monthly filing from October, change it by 31 Oct; otherwise your current choice continues.

Checklist for 13 October

All Jul–Sep invoices, credit and debit notes listed
Invoices already in Jul/Aug IFF not repeated
B2C summary and HSN summary filled
Customer GSTINs checked
GSTR-1 filed with EVC or DSC by 13 Oct, acknowledgment saved
Decide quarterly vs monthly for Oct–Dec before 31 Oct
Calendar reminder: IFF for October by 13 Nov (if you use it)

Frequently asked questions

What is the GSTR-1 due date for QRMP filers for July–September 2026?

13 October 2026, the 13th day of the month after the quarter. As of 13 October 2026 we found no notification extending it.

Is IFF mandatory for QRMP taxpayers?

No. IFF is optional. Use it only if you want your registered customers to get input tax credit in months 1 and 2 of the quarter.

What is the IFF limit?

The total value of invoices in one month's IFF cannot exceed ₹50 lakh. Above that the portal will not allow filing.

Is there a late fee for IFF?

No. IFF simply expires after the 13th of the next month; unfiled invoices go into the next IFF or the quarterly GSTR-1.

Can I switch from quarterly to monthly GSTR-1 for October–December 2026?

Yes, the frequency for the October–December quarter can be changed from 1 August to 31 October.

Official sources

Not tax or legal advice. This is a free explainer of public rules; deadlines and rules can change by notification, so confirm on the official portal or with your CA before you file. Last checked 11 Oct 2026.

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