Filed GSTR-1 with a mistake: amendments and GSTR-1A

A filed GSTR-1 cannot be revised or deleted. You correct it in one of two ways. If GSTR-3B for the same period is not filed yet, use Form GSTR-1A. If it is, use the amendment tables of a later GSTR-1. Both routes close on 30 November after the financial year, or with your annual return if that is earlier.

Which route applies to your mistake?

GST has no revised return because your invoices feed your buyers' credit and your own GSTR-3B. So the law lets you correct forward. Check one thing first: is GSTR-3B for that period filed?

If the mistake is a sale you left out, the steps are in missed sales in GSTR-1. This article covers changing what you did report.

What is Form GSTR-1A and when does it open?

GSTR-1A is an amendment form for the GSTR-1 you just filed. It came in through Notification 12/2024-Central Tax of 10 July 2024, and the GST Council's newsletter says it was made available from the July 2024 return period.

• It opens after you file GSTR-1 or after the GSTR-1 due date, whichever is later, and stays open until you file GSTR-3B.
• It is filed online only. There is no offline JSON route and no nil GSTR-1A.
• It changes only the current period's records. Quarterly filers can also correct invoices they sent through IFF in the first two months.
• You can add or correct invoices and credit or debit notes. You cannot change a buyer's GSTIN here. That needs a later GSTR-1.
• If you save records in GSTR-1A and do not file it, the portal blocks GSTR-3B until you file, delete or reset it.

Reports of GSTN advisories say sales figures filled into GSTR-3B from GSTR-1 can no longer be edited from the July 2025 period. If so, GSTR-1A is the only way to change them before payment.

Which amendment table do you use in a later GSTR-1?

Table 9B is not an amendment table. It is where credit and debit notes are first reported. For returns, see sales returns in GSTR-1.

Some fields are locked. In Table 10 and Table 11 you cannot edit the State of an existing line. Table 10 has an Add POS button for a new State line. A Table 14A record can be amended only once.

How do you amend a B2B invoice in Table 9A?

1. Open GSTR-1 for the current period on the Returns Dashboard.
2. Open the tile 9A, Amended B2B Invoices.
3. Select the financial year of the original invoice, enter its number and click Amend Invoice.
4. Enter the revised invoice number and date and the corrected values. Save.
5. Generate the summary, check it and file GSTR-1.
6. Pay any extra tax in the same period's GSTR-3B, with interest.

A worked example

Imran's April 2026 GSTR-1 shows a B2B invoice at a taxable value of Rs 5,000. The real value was Rs 50,000, taxed at 18%. He finds the slip in July, after April's GSTR-3B is filed, so GSTR-1A is closed.

He amends the invoice in Table 9A of his July 2026 GSTR-1. The portal adds tax only on the difference: 18% of Rs 45,000, which is Rs 8,100. He pays it in July's GSTR-3B on 20 August 2026. The tax was due on 20 May, so interest runs for 92 days. At 18% a year that is Rs 8,100 x 18% x 92/365, about Rs 367. For a 2025-26 invoice, the last date to do this would be 30 November 2026.

What mistake do sellers usually make?

They enter the correct invoice again as a new invoice in Table 4. The portal treats a repeated invoice number in the same financial year as a duplicate, and a changed number counts the sale twice. Others fix only the GSTR-3B figure and leave GSTR-1 wrong, which leaves a gap between the two returns.

Should you do it yourself?

One invoice is a ten-minute job. Take help when the error runs across months, touches place of supply for many States, or sits in Table 14 for a marketplace, where each record can be amended only once.

Frequently asked questions

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