| Feature | GSTR-1 | GSTR-1A | GSTR-3B |
|---|---|---|---|
| Purpose | Declare all outward supplies (sales) for the tax period | Add or amend outward-supply records of the same period already filed in GSTR-1 | Summary return that pays the net tax liability |
| Timing | By the monthly or quarterly due date (11th or 13th) | After GSTR-1 is filed and before GSTR-3B of the same period | By the 20th (or 22nd/24th for QRMP) of the next month |
| Mandatory? | Yes | No, fully optional | Yes |
| Can add missed invoices? | Yes | Yes, for the current period only | No |
| Can amend recipient GSTIN? | Yes (in a later period) | No, never | No |
| How often | One per period | One per period | One per period |
| Feeds | GSTR-3B and recipient GSTR-2B | GSTR-3B and recipient GSTR-2B | Cash and credit ledgers |
If you filed GSTR-1 in a hurry and then spotted a wrong taxable value, a missed sales invoice, or a tax-rate slip, GSTR-1A is the return that lets you fix it for the same tax period before you file GSTR-3B. It is an optional amendment facility that keeps your auto-populated GSTR-3B liability correct, which matters now that the GSTR-3B tax tables are locked. This guide explains exactly when to use it, what it can and cannot change, and how to file it on the portal.
GSTR-1A is the right tool whenever the error sits in the outward-supply data of the current period and you have already filed GSTR-1 but not yet GSTR-3B. Typical situations include:
Because GSTR-3B tax tables can no longer be hand-edited, GSTR-1A has become the practical correction window. The facility was reintroduced by Notification No. 12/2024-Central Tax dated 10 July 2024, which inserted a proviso to Rule 59(1) of the CGST Rules, and it is available from the July or August 2024 return period onward.
Amendments and additions you make through GSTR-1A do not vanish for your buyer. They flow to the recipient, but generally in the following period's GSTR-2B rather than the same one. So if you add a missed June invoice through June GSTR-1A, your buyer typically sees that input tax credit reflected in their July GSTR-2B. This is why prompt use of GSTR-1A protects your customer relationships: a missed invoice fixed quickly still lets the buyer claim credit, just one cycle later. Buyers tracking these movements should understand the GST Invoice Management System and ITC, since IMS is where accepted, rejected, and pending records ultimately settle a recipient's credit.
From the July 2025 tax period (the return filed in August 2025), the GST Network hard-locked the auto-populated liability in GSTR-3B Tables 3.1 and 3.2. These tables now draw straight from GSTR-1, IFF, and GSTR-1A, and the taxpayer can no longer overwrite them by hand. Before this change, many businesses simply typed the correct figure into GSTR-3B and moved on. That shortcut is gone. The only clean way to correct an outward-supply number for the current period is GSTR-1A; otherwise the mistake either gets paid as-is or waits for a next-period amendment. Treat GSTR-1A as a routine pre-3B check rather than an emergency tool.
A consultancy such as Sunrise Advisory, for example, that issued a ₹50,000 invoice but typed ₹5,000 in GSTR-1 can add the corrected value through GSTR-1A the same month, so its locked GSTR-3B liability is right the first time.
No. GSTR-1A is entirely optional. You file it only when you need to add or amend an outward-supply record of the current period before filing GSTR-3B.
No. The GSTR-1A window for a period closes the moment you file GSTR-3B for that same period. After that, corrections move to the next period's GSTR-1.
Only once per tax period. Plan all your corrections together so the single GSTR-1A captures every change you need for that period.
Yes, but generally in the following period's GSTR-2B rather than the current one. The credit still reaches the buyer, just one cycle later.
Yes. QRMP taxpayers who file GSTR-1 quarterly can use GSTR-1A to amend quarterly outward supplies before filing the quarterly GSTR-3B, subject to the same one-per-period and pre-3B rules.
Yes. Place of supply, taxable value, tax rate, and supply type can all be corrected through GSTR-1A. Only the recipient GSTIN is off limits.