GSTR-1A: The Amendment Window That Opens on the 11th and Shuts When You File GSTR-3B
Sunday 14 June 2026 sits inside the GSTR-1A corridor for the May tax period. Here is what monthly GST filers, advance-tax payers and Monday's reopening market must watch.
Markets are shut on Sunday 14 June 2026, but the compliance clock never stops. For every monthly GST filer who has already submitted GSTR-1 for the May 2026 tax period (due 11 June 2026), an amendment facility called GSTR-1A is now live and ticking towards a single hard stop: the moment you file GSTR-3B. The GST Network's own user guide is unambiguous that GSTR-1A has no separate due date of its own. It opens from the later of the GSTR-1 due date or the actual GSTR-1 filing date, and it stays open only until you file GSTR-3B for the same tax period.
That makes the next 6 days a quiet but consequential window. With GSTR-3B for May 2026 due on 20 June 2026 for monthly filers, the corridor to correct an outward-supply error without waiting for next month runs from 11 June to the instant you hit submit on GSTR-3B. Below we map the statutory deadlines stacked into the week, the Monday market reopening, and the advance-tax instalment that lands on 15 June 2026.
Statutory Deadlines
The headline item for the next 48 hours is not a single calendar date but a window. GSTR-1A lets a monthly filer amend or add records of outward supplies that belong to the same tax period for which GSTR-1 was already filed. Per the GST portal FAQ, it becomes available from the later of the 11th-of-the-following-month GSTR-1 due date or the actual filing date, and it closes the moment GSTR-3B is filed. For the May 2026 period, that means the window has been open since GSTR-1 was filed on or after 11 June 2026 and will slam shut on or before 20 June 2026, the GSTR-3B due date for monthly filers under Section 39 of the CGST Act 2017.
Why this matters in practice: any correction made in GSTR-1A flows into the auto-populated liability of GSTR-3B for the same period, so you fix the error and pay the right tax in one cycle rather than carrying a mismatch into June's return. Miss the window, and the same correction can only be made through the ordinary amendment route in a later GSTR-1, delaying the input-tax-credit reconciliation your buyers depend on.
The table below sets out the monthly-filer corridor for the May 2026 tax period.
| Form | Statutory due date (May 2026 period) | Status on Sun 14 June 2026 |
|---|---|---|
| GSTR-1 (monthly outward supplies) | 11 June 2026 | Closed - filing window passed |
| GSTR-1A (amendment of same period) | No separate due date | OPEN until GSTR-3B is filed |
| GSTR-3B (summary return and tax payment) | 20 June 2026 | Open - filing not yet due |
A second statutory deadline lands the day after tomorrow. The first instalment of advance tax for the financial year 2026-27 is due on 15 June 2026, a Monday. Under Section 211 of the Income-tax Act 1961, individuals and companies with an estimated annual tax liability of Rs 10,000 or more must deposit 15% of their estimated tax by this date. Salaried taxpayers whose employers deduct TDS in full can usually skip this instalment, but professionals, traders and those with capital gains or rental income should run the numbers this weekend rather than on Monday morning. Our advance-tax glossary entry explains the four-instalment schedule, and the self-assessment-tax note covers what happens if you fall short.
The second table summarises the instalment ladder so you can confirm whether 15 June applies to you.
| Advance-tax instalment (FY 2026-27) | Cumulative % of estimated tax | Due date |
|---|---|---|
| First | 15% | 15 June 2026 |
| Second | 45% | 15 September 2026 |
| Third | 75% | 15 December 2026 |
| Fourth | 100% | 15 March 2027 |
Deductors who collect tax at source should also note that GST TDS returns in GSTR-7 and TCS returns in GSTR-8 for the May period carried a 10 June deadline that has already passed; the relevance for tomorrow is only the late-fee meter, which keeps running until the return is filed.
Market Events
There are no live market events on Sunday 14 June 2026 because the National Stock Exchange and BSE cash and derivatives segments do not trade at weekends. The watch item is the reopening on Monday 15 June 2026, which coincides exactly with the advance-tax deadline above, so treasury desks at listed companies will be moving cash before the 11:00 cut-off for tax payments.
The monetary-policy backdrop is settled for now. The RBI Monetary Policy Committee held the repo rate at 5.25% at its meeting on 8 April 2026, the second consecutive pause, after a cumulative 125 basis points of cuts through 2025 took the rate down from 6.50%. With the June MPC review (3-5 June 2026) already behind us and the rate left unchanged, there is no rate trigger pending for Monday's session; the next scheduled review falls later in the year. Our repo-rate glossary entry explains how an EBLR-linked floating loan resets within roughly three months of any change, so borrowers have nothing new to price in this week.
For investors who use the weekend to rebalance rather than react, a flat-rate environment is a reminder that systematic contributions usually beat market timing. You can model a monthly plan on our SIP calculator or test a one-off deployment on the lumpsum calculator before Monday's open. Last week we covered how QRMP taxpayers preserve buyer credit between quarters in our piece on the 13th IFF cut-off, which dovetails with this week's GSTR-1A theme.
Earnings
No company results are scheduled for Sunday 14 June 2026. Indian listed companies do not announce audited or unaudited financials on a non-trading day, and our briefing for this watchlist confirms no earnings on the calendar for tomorrow. The Q4 FY 2025-26 results season, which runs into the 60-day window after the 31 March 2026 year-end, has largely concluded, and the next earnings cluster is the Q1 FY 2026-27 cycle that begins after the 30 June 2026 quarter closes.
That leaves the practical takeaway for the weekend firmly on compliance rather than trading. If you are a monthly GST filer, log in to the portal, check whether any May invoice was missed or wrongly reported, and use GSTR-1A to fix it before you file GSTR-3B by 20 June 2026. If you owe advance tax, deposit the first 15% instalment by 15 June 2026 to avoid interest under Sections 234B and 234C of the Income-tax Act 1961. And if you simply want to put idle cash to work, a flat 5.25% repo backdrop is as good a time as any to automate a step-up SIP rather than wait for a rate signal that the June MPC has already removed.
FAQ
Does GSTR-1A have its own due date?
No. The GST portal user guide states that GSTR-1A has no separate due date. It opens from the later of the GSTR-1 due date (11th of the following month) or the actual GSTR-1 filing date, and it stays open only until GSTR-3B for the same tax period is filed, which for May 2026 means up to 20 June 2026 for monthly filers.
Can I use GSTR-1A after I have filed GSTR-3B?
No. Filing GSTR-3B is the event that closes the GSTR-1A window for that period. Once GSTR-3B for May 2026 is filed, any further correction must be made through an ordinary amendment in a subsequent GSTR-1, not through GSTR-1A.
What can I actually change in GSTR-1A?
GSTR-1A lets a monthly filer amend or add records of outward supplies that belong to the same tax period as the GSTR-1 already filed. The amended figures flow into the auto-populated liability of GSTR-3B for that period, so the corrected tax is paid in the same cycle.
Who must pay advance tax by 15 June 2026?
Under Section 211 of the Income-tax Act 1961, any taxpayer whose estimated annual tax liability is Rs 10,000 or more must pay 15% of that estimate as the first instalment by 15 June 2026. Salaried individuals with full TDS deduction are generally exempt, but those with business, professional, capital-gains or rental income should pay.
Are the stock markets open on 14 June 2026?
No. Sunday 14 June 2026 is a non-trading day for the NSE and BSE cash and derivatives segments. The next session is Monday 15 June 2026, the same day the advance-tax first instalment falls due.
Is there an RBI rate decision pending this week?
No. The RBI Monetary Policy Committee held the repo rate at 5.25% on 8 April 2026 and again at its June review on 3-5 June 2026. There is no rate trigger scheduled for the coming week.
What happens if I miss the GSTR-1A window for May 2026?
The error is not lost, but it is delayed. You can still correct it through the standard amendment fields in a later GSTR-1, which pushes the input-tax-credit reconciliation for your buyers into a subsequent month rather than settling it in the May cycle.
Sources & Citations
- FAQs - Creation of Outward Supplies Return in GSTR-1A — Government of India - GST Network
- Advance Tax - Income Tax Department — incometax.gov.in
- Central Goods and Services Tax Act 2017 — indiacode.nic.in
Frequently Asked Questions
Does GSTR-1A have its own due date?
No. The GST portal user guide states that GSTR-1A has no separate due date. It opens from the later of the GSTR-1 due date (11th of the following month) or the actual GSTR-1 filing date, and stays open only until GSTR-3B for the same tax period is filed, which for May 2026 means up to 20 June 2026 for monthly filers.
Can I use GSTR-1A after I have filed GSTR-3B?
No. Filing GSTR-3B is the event that closes the GSTR-1A window for that period. Once GSTR-3B for May 2026 is filed, any further correction must be made through an ordinary amendment in a subsequent GSTR-1, not through GSTR-1A.
What can I actually change in GSTR-1A?
GSTR-1A lets a monthly filer amend or add records of outward supplies that belong to the same tax period as the GSTR-1 already filed. The amended figures flow into the auto-populated liability of GSTR-3B for that period, so the corrected tax is paid in the same cycle.
Who must pay advance tax by 15 June 2026?
Under Section 211 of the Income-tax Act 1961, any taxpayer whose estimated annual tax liability is Rs 10,000 or more must pay 15% of that estimate as the first instalment by 15 June 2026. Salaried individuals with full TDS deduction are generally exempt, but those with business, professional, capital-gains or rental income should pay.
Are the stock markets open on 14 June 2026?
No. Sunday 14 June 2026 is a non-trading day for the NSE and BSE cash and derivatives segments. The next session is Monday 15 June 2026, the same day the advance-tax first instalment falls due.
Is there an RBI rate decision pending this week?
No. The RBI Monetary Policy Committee held the repo rate at 5.25% on 8 April 2026 and again at its June review on 3-5 June 2026. There is no rate trigger scheduled for the coming week.
What happens if I miss the GSTR-1A window for May 2026?
The error is not lost, but it is delayed. You can still correct it through the standard amendment fields in a later GSTR-1, which pushes the input-tax-credit reconciliation for your buyers into a subsequent month rather than settling it in the May cycle.