GSTR-1A: Fix GSTR-1 Errors Before GSTR-3B 2026

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:

• You forgot to report a B2B invoice issued during the period.
• You entered a wrong taxable value, tax rate, or place of supply.
• You reported a B2C supply that should have been B2B, or the reverse.
• You missed a credit note or debit note of the current period.
• The auto-populated liability in GSTR-3B looks wrong and you traced it to a GSTR-1 mistake.

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.

• Add any outward-supply record of the current period you missed in GSTR-1.
• Correct the taxable value, tax amount, or tax rate of a reported invoice.
• Fix the place of supply or the supply type (B2B, B2C, exports, SEZ).
• Amend current-period credit notes and debit notes.
• Adjust advances received and adjustments of advances for the same period.

• You cannot change the recipient GSTIN. Per the GST portal FAQ, a wrong counter-party GSTIN must be corrected in the GSTR-1 of a following tax period, not in GSTR-1A.
• You cannot fix any earlier period. GSTR-1A is strictly for the current period; older mistakes go through the amendment tables of a regular GSTR-1.
• You cannot file more than one GSTR-1A for a single tax period.
• You cannot file GSTR-1A after GSTR-3B for that period is filed. Once GSTR-3B goes in, the window shuts.

1. Log in to the GST portal and open Services > Returns > Returns Dashboard.
2. Select the financial year and the relevant tax period, then file your GSTR-1 first. GSTR-1A only opens after the GSTR-1 due date or the actual filing date, whichever is later.
3. On the dashboard, locate the GSTR-1A tile, which appears once GSTR-1 is filed and stays open until GSTR-3B is filed.
4. Click Prepare Online. The relevant tables mirror GSTR-1 so you can add new records or amend existing ones.
5. Enter the corrected or additional invoices. Leave the recipient GSTIN field as originally reported, since it cannot be changed here.
6. Use Generate Summary to review the revised totals and confirm the net effect on your liability.
7. File GSTR-1A with DSC or EVC. The corrected figures then flow into the auto-populated GSTR-3B.
8. Proceed to file GSTR-3B for the same period, where the liability now reflects both GSTR-1 and GSTR-1A.

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.

• Trying to fix the recipient GSTIN here. It will not work; plan a next-period GSTR-1 amendment instead.
• Waiting too long. Once GSTR-3B is filed, GSTR-1A for that period is permanently closed.
• Expecting same-period ITC for the buyer. The credit generally appears in the buyer's next GSTR-2B.
• Using it for old errors. Earlier-period corrections belong in regular GSTR-1 amendment tables, not GSTR-1A.
• Skipping the summary. Always generate and read the summary so the revised liability is what you expect before filing GSTR-3B.

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.

• GSTR-7: TDS under GST deductor return
• GSTR-9 annual return filing guide
• How to apply for GST registration in 2026
• AI RTI draft tool for filing an RTI on a stuck GST grievance
• The RTI Playbook for using the Right to Information Act to push pending tax matters

• Notification No. 12/2024-Central Tax dated 10 July 2024, proviso to Rule 59(1), CGST Rules.
• GST portal FAQs on Form GSTR-1A, tutorial.gst.gov.in.
• GSTN advisory on hard-locking of auto-populated GSTR-3B liability from July 2025.
• CBIC introduction of Form GSTR-1A, 2024 CGST Amendment Rules.