Last updated: 8 September 2026. Three separate GST filings for the August 2026 period fall due on Sunday, 13 September 2026: the Invoice Furnishing Facility (IFF) for QRMP taxpayers, GSTR-5 for non-resident taxable persons, and GSTR-6 for Input Service Distributors. They bind three different groups of people, carry three different consequences, and only one of them is optional.
Applicability Note: This guide reflects GST provisions and CBIC notifications applicable as of 8 September 2026. Due dates change through CBIC notifications, and no extension has been notified for the August 2026 period as of this writing. Always verify the current position on gst.gov.in or with a GST professional before filing.
Who Should Care?
This guide applies to:
- QRMP taxpayers — aggregate turnover up to ₹5 crore in the preceding financial year, filing quarterly. August is Month 2 of the July–September quarter, which makes this your last IFF of the quarter
- Non-resident taxable persons registered under Section 24 — and anyone whose registration is due to expire, because your deadline may be earlier than the 13th
- Input Service Distributors — including every group that took ISD registration when it became compulsory from 1 April 2025 and now files GSTR-6 every month
- Anyone buying from a QRMP supplier who is waiting on input tax credit for an August invoice
1. What Falls Due on Sunday 13 September 2026
| Form | Who files it | Period | Mandatory? |
|---|---|---|---|
| IFF | QRMP taxpayers reporting B2B invoices | August 2026 (Month 2) | No — optional, and it expires |
| GSTR-5 | Non-resident taxable persons | August 2026 | Yes — and tax is paid with it |
| GSTR-6 | Input Service Distributors | August 2026 | Yes — including a nil return |
Three forms, one date, no shared rulebook. The IFF sits in Rule 59(2) of the CGST Rules; GSTR-5 and GSTR-6 sit in different sub-sections of Section 39 of the CGST Act, and their late fees come from two different notifications issued on the same day in 2018 — which is why they are treated separately below.
2. The IFF: Your Last Upload Before the Quarter Closes
The Invoice Furnishing Facility lets a QRMP supplier push B2B invoices to the portal in the first two months of a quarter, instead of making the buyer wait for the quarterly GSTR-1. Rule 59(2) sets the boundaries: supplies to a registered person, up to a cumulative ₹50 lakh in each of those months, uploaded from the 1st of the following month to the 13th.
August is Month 2 of the July–September quarter. September is Month 3, which has no IFF at all — it settles in the quarterly return. So 13 September is your last IFF upload this quarter, and the question is not whether you will be fined. You will not be. It is when your buyer sees the credit.
Rule 59(3): details of outward supplies furnished using the IFF for the first and second months of a quarter "shall not be furnished in FORM GSTR-1 for the said quarter." Anything you upload now is out of the quarterly return; anything you leave out goes into it.
Upload an August invoice by the 13th and it reaches a monthly-filing buyer's GSTR-2B on 14 September. A buyer who is himself on QRMP gets no GSTR-2B for Month 2 at all and waits until 14 October whatever you do. Leave the invoice out and it goes into the quarterly GSTR-1 filed on 13 October 2026, landing in the buyer's GSTR-2B on 14 October — the same date for a monthly and a QRMP buyer alike. For a monthly buyer chasing credit on a large August purchase, that is a month of working capital, and it is your decision, not theirs.
Four things stop an upload even inside the window, all in Rule 59(6): the preceding tax period's GSTR-3B is unfiled (clause (b)); a Rule 88C intimation is unanswered (clause (d)); a Rule 88D intimation is unanswered (clause (e)); or bank account details have not been furnished under Rule 10A (clause (f)). Discovering one of these on the 13th is not a problem you can solve on the 13th. Our IFF guide works through each block.
There is no late fee for missing the IFF — it is optional, and nothing is levied for skipping it. What closes on the 13th is the ability to save or submit records: after that the window expires and no new August invoice can go in. Records you submitted by the 13th but did not file can still be filed afterwards, and that half-finished state is the one that catches people out — submitted is not filed, and only filed records travel to your buyer.
3. GSTR-5: A Deadline That Can Arrive Before the 13th
GSTR-5 is the return of a non-resident taxable person — someone supplying goods or services in India without a fixed place of business here. It reports outward and inward supplies together, and the tax is paid with it: Section 39(7) requires the tax due no later than the last date for furnishing the return.
The due date has two limbs, and most people only remember one. Section 39(5) requires the return within thirteen days after the end of a calendar month, or within seven days after the last day of the period of registration under Section 27(1), whichever is earlier. A non-resident registration is valid for the period applied for or ninety days, whichever is earlier, extendable once by up to ninety more days. So if your registration lapsed on 4 September, your GSTR-5 was due on 11 September, not the 13th — the second limb bit first.
Worth knowing: Section 39(5) has set thirteen days since 1 October 2022, substituted for twenty by section 105 of the Finance Act 2022 and brought into force by Notification No. 18/2022-Central Tax dated 28 September 2022. Rule 63, which prescribes the form, was never aligned and still sets a twenty-day period for furnishing the return and paying the tax — but the statutory limit in Section 39(5) is what binds, and the portal enforces the 13th.
Two more things catch non-residents out. First, credit: Section 17(5)(f) blocks input tax credit on goods or services received by a non-resident taxable person except on goods imported by him. Local purchases and imported services carry no credit at all, so the GSTR-5 liability is usually settled in cash. Second, the money is already there — Section 27(2) requires an advance deposit of estimated tax when the registration is applied for, and Section 27(3) credits it to the electronic cash ledger.
4. GSTR-6: The Return an ISD Files Even With Nothing to Distribute
An Input Service Distributor is the office that receives common input service invoices for a group and passes the credit out to the GSTINs that consumed the service. Since 1 April 2025 that registration is compulsory where the mechanism applies, so a large number of groups are now in their second year of filing GSTR-6 every month.
Section 39(4) sets the deadline: within thirteen days after the end of the month. Rule 65 prescribes the form itself, built on the details in FORM GSTR-6A, and carries no date of its own — the 13th comes from the Act.
The GST portal is explicit that GSTR-6 is a mandatory monthly return and that a nil GSTR-6 must be filed where no credit is available for distribution or none is distributed. This is where ISDs lose money for nothing: a quiet month with no common invoices still needs a return, and the fee for a late nil GSTR-6 is not reduced (section 5 below). What the ISD distributes flows into each recipient's GSTR-2B and auto-populates Table 4(A)(4) of that recipient's GSTR-3B, so a skipped GSTR-6 strands credit on a GSTIN with no output liability to use it against. Our guide to ISD credit distribution covers the mechanics and the penalty exposure under Section 122(1)(ix), where ₹10,000 is a floor rather than a ceiling.
5. What Missing Each One Costs
Late fees below are stated as CGST + SGST/UTGST combined. Each Act carries half of the figure shown, and the ceiling in Section 47(1) is ₹5,000 per Act.
| Form | Late fee (total) | Nil return | Ceiling (total) | Governing instrument |
|---|---|---|---|---|
| IFF | None | — | — | Optional facility under Rule 59(2); the save/submit window closes on the due date |
| GSTR-5 | ₹50 per day | ₹20 per day, where the central tax payable in the return is nil | ₹10,000 | Notification No. 5/2018-Central Tax dated 23 January 2018 |
| GSTR-6 | ₹50 per day | No reduced rate — a nil GSTR-6 carries the same ₹50 a day | ₹10,000 | Notification No. 7/2018-Central Tax dated 23 January 2018 |
That middle column is easy to get backwards. Notification 5/2018 carries a proviso cutting the GSTR-5 fee where the central tax payable in the return is nil. Notification 7/2018, issued the same day for GSTR-6, has a single operating paragraph and no such proviso. Two forms, one due date, two rulebooks — never read one form's concession across to the other.
Interest is a separate matter and it only touches GSTR-5. Tax paid late attracts 18% per annum under Section 50(1), at the rate notified by Notification No. 13/2017-Central Tax dated 28 June 2017. An ISD pays no tax through GSTR-6, so a late GSTR-6 carries the fee and nothing else.
Two structural bars sit behind all of this. Section 39(10) stops you filing for a period while an earlier period's return is outstanding, so arrears clear in order. And Section 39(11) bars any return filed more than three years after its due date, subject to a notified relaxation.
6. The 13th Is a Sunday, and the Date Does Not Move
13 September 2026 falls on a Sunday, and so does the 20th. Neither shifts. No CBIC notification rolls a GST due date forward for a weekend, and the general provision people reach for — Section 10 of the General Clauses Act, 1897 — applies where the court or office is closed on that day, or on the last day of the prescribed period. The common portal is open. No ruling either way applies Section 10 to a GST return due date, so the position is unsettled — and building a filing plan on it is not worth ₹50 a day.
The practical version: treat Friday 11 September as your working deadline. That is also the day the monthly GSTR-1 for August is due, so a monthly filer is at the portal anyway. If GSTR-5 tax has to be paid, the cash has to reach the ledger before it can be offset, and a challan generated on a Sunday afternoon is not a plan.
Nothing short of a notification changes a notified due date, and none has issued for the August 2026 period.
7. A Working Order for the Next Four Days
- QRMP suppliers: pull every August B2B invoice, check the ₹50 lakh cumulative cap, and clear any Rule 59(6) block before the weekend. Anything you skip goes to the buyer on 14 October
- Non-residents: check the validity date on the registration certificate first, not the calendar. If it expired or expires this month, the seven-day limb may already have set an earlier date
- ISDs: reconcile GSTR-6A, distribute, and file — even for a nil month. There is no reduced fee waiting for you if you leave it
- Everyone: check whether an earlier period's return is outstanding, because Section 39(10) will block the current one until it is filed
PMT-06 for QRMP filers follows on Friday 25 September, and GSTR-3B for monthly filers on Sunday 20 September. The full month is in our September 2026 filing calendar.
Key Takeaways
- Three forms, one Sunday. IFF, GSTR-5 and GSTR-6 for the August 2026 period all fall due on 13 September 2026, and the date does not move for the weekend.
- This is the last IFF of the July–September quarter. August is Month 2; Month 3 has no IFF. An invoice left out now reaches your buyer's GSTR-2B on 14 October rather than 14 September — though a buyer who is himself on QRMP waits until 14 October either way.
- A non-resident's deadline can be earlier than the 13th. Section 39(5) takes the earlier of thirteen days after month-end and seven days after the registration period ends — and that registration runs ninety days unless extended.
- A nil GSTR-6 is still a GSTR-6. The portal requires it, and Notification 7/2018 gives it no reduced late fee — ₹50 a day either way, to a ₹10,000 ceiling.
- GSTR-5 and GSTR-6 never share a fee row. Only GSTR-5 has a nil concession, and only GSTR-5 carries tax — so only GSTR-5 attracts 18% interest.
Frequently Asked Questions
Is there a late fee if I miss the IFF on 13 September 2026?
No. The IFF is an optional facility under Rule 59(2) and nothing is levied for skipping it. What closes on 13 September is the ability to save or submit records — after that no new August invoice can go in, though records already submitted by the 13th can still be filed. The cost is timing: anything left out goes into the quarterly GSTR-1 filed on 13 October 2026 and reaches your buyer's GSTR-2B on 14 October.
When is GSTR-5 due if the non-resident registration expires mid-month?
Whichever comes first. Section 39(5) sets the earlier of thirteen days after the end of the calendar month and seven days after the last day of the period of registration under Section 27(1). A registration that lapsed on 4 September put the GSTR-5 due on 11 September, ahead of the 13th — so check the certificate before the calendar.
Do I have to file GSTR-6 if the ISD distributed no credit in August?
Yes. The GST portal treats GSTR-6 as a mandatory monthly return and requires a nil return where no credit is available for distribution or none is distributed. Unlike GSTR-5, a nil GSTR-6 gets no reduced late fee — Notification No. 7/2018-Central Tax dated 23 January 2018 contains no nil-return proviso.
Can a non-resident taxable person claim input tax credit in GSTR-5?
Only on goods imported by them. Section 17(5)(f) blocks credit on goods or services received by a non-resident taxable person except on imported goods, so local purchases and imported services carry no credit and the liability is generally settled in cash — usually out of the advance deposit made under Section 27(2).
Disclaimer: This article is for informational purposes only and does not constitute professional tax advice. GST rules are subject to frequent changes through notifications and circulars. Please verify the current provisions on the official GST portal (gst.gov.in) before making any compliance decisions.
Have a question about your IFF window, a non-resident registration, or an ISD distribution for August? Our GST experts can help → gstconsultancy.com