What is GSTR-1A?
GSTR-1A is an amendment return for GSTR-1, the monthly or quarterly statement of your sales. It was brought in by Notification 12/2024-Central Tax of 10 July 2024, which added it to Rule 59 of the CGST Rules (the Central Goods and Services Tax Rules). Rule 59 now lets you, after filing GSTR-1 for a period but before filing GSTR-3B for the same period, "amend or furnish additional details" of your sales in GSTR-1A.
There is no revising GSTR-1 itself. Before GSTR-1A, a mistake waited for the amendment tables of the next month's GSTR-1. GSTR-1A lets you fix it inside the same month, before the tax is paid.
Why it matters more since July 2025
GSTR-3B is the return in which you pay the month's tax. Its Table 3, the tax on your sales, is filled in from GSTR-1 and GSTR-1A. A GSTN (Goods and Services Tax Network, which runs the portal) advisory of 7 June 2025 made that figure non-editable in GSTR-3B from the July 2025 tax period. So if GSTR-1 is wrong, GSTR-1A is the only way to correct the tax before you pay it. After GSTR-3B is filed, the correction moves to a later GSTR-1.
When can I file GSTR-1A?
| You file | GSTR-1A opens | GSTR-1A closes |
|---|---|---|
| GSTR-1 monthly | The 11th, or the day you filed GSTR-1, whichever is later | When you file GSTR-3B for that month |
| GSTR-1 quarterly (QRMP, quarterly return, monthly payment) | The 13th after the quarter, or the day you filed, whichever is later | When you file GSTR-3B for that quarter |
Example: you file October 2026's GSTR-1 on 9 Nov 2026. GSTR-1A for October opens on 11 Nov 2026, the due date, and stays open until you file October's GSTR-3B, due on 20 Nov 2026. If you file GSTR-1 on 12 Nov 2026, GSTR-1A opens that day.
GSTR-1A has no due date of its own and no late fee. It is optional, and a nil GSTR-1A cannot be filed.
What can GSTR-1A change?
Rule 59(4A) lists what it can carry, for the same tax period only:
- Invoices to registered buyers (B2B), one by one.
- Inter-state invoices above ₹1,00,000 to consumers (B2CL), one by one.
- Consumer sales summarised by rate (B2CS): intra-state sales, and inter-state sales up to ₹1,00,000, state by state.
- Credit and debit notes issued in the period.
You can amend records already in that period's GSTR-1, including invoices a quarterly filer uploaded through IFF (the invoice furnishing facility) in the first two months, and add records that were left out. The HSN summary (Table 12) carries the matching change; a reduction is entered with a minus sign.
What GSTR-1A cannot do
- Change a buyer's GSTIN. A B2B invoice reported against the wrong GSTIN is corrected only through the GSTR-1 of a later period.
- Reach an earlier month. GSTR-1A amends only the current period's GSTR-1. Records from earlier periods are amended in a later GSTR-1.
- Be filed twice. It can be filed once for a period, even if GSTR-3B is still open.
- Be filed after GSTR-3B. Once GSTR-3B for the period is filed, GSTR-1A for it is closed.
Corrections to a past financial year, through any route, stop on 30 November after the year ends, or when you file that year's annual return, if earlier (section 37(3) of the CGST Act). For invoices of 2025-26, that is 30 Nov 2026.
How do I file it?
On the portal, under Returns, the GSTR-1A tile appears for the period once it opens. It can be prepared online or through a GSP (GST Suvidha Provider, a company licensed to connect software to the portal), not with the offline tool. Two things to watch:
- Do not leave it half done. If you save records in GSTR-1A and do not file it, the portal will not let you file GSTR-3B. File it, delete the saved records or reset it.
- Your buyers see it a month later. Credit on an invoice added or amended in GSTR-1A reaches the buyer's GSTR-2B for the next period. An October invoice added in GSTR-1A on 15 Nov 2026 appears in the buyer's November GSTR-2B, made on 14 Dec 2026.
Where it comes from in practice
The usual cause is a document dated in the month but issued after GSTR-1 was filed: a credit note for a late return, or an order invoiced late. AppSaaz keeps a GSTR-1A report of exactly those documents, the ones created after you marked the month filed, laid out the way GSTR-1 is, so you know what belongs in the amendment before GSTR-3B.