GST glossary
GSTR-1A
Amendment of outward supplies for the current tax period
GSTR-1A is an optional form on the GST portal for adding or correcting sales invoices of a tax period after GSTR-1 has been filed and before GSTR-3B is filed for the same period. The corrected figures then flow into GSTR-3B.
Why it matters to your business
Until 2024, a mistake noticed after filing GSTR-1 waited until the next month, and you adjusted the tax by hand in GSTR-3B. Now the liability in GSTR-3B comes straight from what you reported and is locked. GSTR-1A is the one chance to put the month right before you pay.
How it works
As of October 2026:
- GSTR-1A was introduced by Notification 12/2024-Central Tax of 10 July 2024.
- It opens after GSTR-1 is filed (for quarterly filers, after the quarter’s GSTR-1) and closes when GSTR-3B for the period is filed.
- You add missed documents or amend reported ones. The net effect is added to the liability shown in GSTR-3B.
- It is optional. If GSTR-1 was right, there is nothing to file.
An example
A trader files GSTR-1 for September on 10 October and, on 15 October, finds an invoice of ₹1,18,000 that was left out. The trader adds it through GSTR-1A on the same day. GSTR-3B, filed on 20 October, shows the tax on it, and the customer sees the invoice in the GSTR-2B generated on 14 November.
Common mistakes
- Filing GSTR-3B first and then looking for GSTR-1A, which has closed by then.
- Trying to correct a customer’s GSTIN through GSTR-1A.
- Using GSTR-1A every month in place of checking GSTR-1 before filing.
Questions about GSTR-1A
When can I file GSTR-1A?
After you file GSTR-1 for a period, until you file GSTR-3B for that period. It can be filed once for each period.
What can be changed through GSTR-1A?
You can add invoices you missed and correct details of invoices already reported, such as value, tax and place of supply. The customer's GSTIN cannot be changed there; that correction goes in the next period's GSTR-1.
Why does GSTR-1A matter more now?
From the July 2025 tax period, the tax liability in GSTR-3B is filled from GSTR-1, GSTR-1A and the IFF and cannot be edited there. A mistake in GSTR-1 can be fixed for the same month only through GSTR-1A.
When does my customer see an invoice added through GSTR-1A?
In their GSTR-2B for the following month, since the current month's GSTR-2B is already generated by then.
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