GSTR-1A: Correcting GSTR-1 Before You File GSTR-3B

GSTR-1A is an optional form on the GST portal that lets you correct or add sales for the same month after you have filed GSTR-1, but before you file GSTR-3B. The corrected figures then flow into that month's GSTR-3B, so you pay the right tax the first time instead of fixing it a month later.

Why does GSTR-1A exist?

GSTR-1 is your statement of sales, and GSTR-3B is the return in which you pay tax. The portal fills your GSTR-3B sales figures from GSTR-1. So a mistake in GSTR-1 travels straight into the tax you pay.

Before GSTR-1A, you had two poor choices. You could edit the figure inside GSTR-3B, which left GSTR-1 and GSTR-3B disagreeing. Or you could fix it in next month's GSTR-1 and pay the tax a month late, with interest. GSTR-1A closes that gap. It was added to the CGST Rules through Notification 12/2024-Central Tax dated 10 July 2024.

It matters more now. GSTN advisories in 2025 said the sales liability that flows from GSTR-1 into GSTR-3B would stop being editable from the July 2025 tax period, with GSTR-1A as the route for changes. If your screen does not allow an edit in GSTR-3B, GSTR-1A is the way to correct the same month.

When can you file it?

So if you file your August GSTR-1 on 9 September, GSTR-1A opens on 11 September. If you file it late, on 15 September, it opens that day. Monthly GSTR-3B is due on the 20th, so in practice your window is about a week. Quarterly filers can also correct invoices they sent through the Invoice Furnishing Facility (IFF) in the first two months of the quarter.

What can and cannot be changed?

A wrong GSTIN is a common slip. If you billed the wrong buyer, that correction has to wait for the amendment table of a later GSTR-1. Our guide on amending GSTR-1 after filing lists those tables.

How to file GSTR-1A

1. File GSTR-1 for the month. Then compare it with your sales register and marketplace reports before you touch GSTR-3B.
2. Log in on the GST portal, open the Returns Dashboard, choose the same tax period and open the GSTR-1A tile.
3. Add the missed invoices, or open a reported invoice and correct it. Add credit or debit notes in their own tables.
4. Check the summary. Only one GSTR-1A is allowed for the period, so get everything in at once.
5. File GSTR-1A with DSC or EVC. It can be prepared online or through a GST Suvidha Provider, not through the offline JSON route.
6. Open GSTR-3B. The corrected sales figures should now be filled in. Pay and file.

What happens on your buyer's side?

If the change touches a sale to a registered business, it reaches your buyer too. Records from GSTR-1A show up in the buyer's Invoice Management System, where the buyer can accept, reject or keep them pending. Our explainer on IMS covers what each action does.

Timing is the catch. GSTR-2B for a month picks up documents filed up to the 11th of the next month for monthly filers. A GSTR-1A filed on, say, 15 September falls after that cut-off, so the buyer will usually see it in the following GSTR-2B, not the August one. Tell a B2B buyer when you add an invoice late, so they know where to look.

Most online sellers sell to consumers, so the buyer side rarely matters. For you, GSTR-1A is mainly about getting your own tax right.

A worked example

Meena sells kitchen storage on two marketplaces and files monthly. She files her August GSTR-1 on 10 September. On 13 September she notices that one marketplace's sales report was left out. Those sales come to Rs 80,000 of taxable value. Say her goods are taxed at 18 percent. The missing tax is Rs 14,400.

She opens GSTR-1A on 13 September, adds the missed sales and files it. Her August GSTR-3B now shows the higher sales, and she pays the full tax by 20 September. There is no interest, and GSTR-1 and GSTR-3B agree.

What if she had skipped GSTR-1A? She would add the sales in the September GSTR-1 and pay the Rs 14,400 with the September GSTR-3B on 20 October, a month late. At an interest rate of 18 percent a year, that is about Rs 213. Confirm the current rate before you rely on this figure. The money is small. The bigger cost is a GSTR-1 and GSTR-3B mismatch for August that can trigger a DRC-01B intimation, explained in replying to DRC-01B.

The mistake sellers usually make

The usual mistake is saving records in GSTR-1A and forgetting to file it. On the 20th, GSTR-3B refuses to file. The fix is simple: file GSTR-1A, or delete the saved records, or reset the form. Do it early, not at 11 pm on the due date.

The second mistake is filing GSTR-1A in a hurry with only half the corrections. You get one GSTR-1A per period. Reconcile first, then file once.

Is this worth doing yourself? If you catch the error before GSTR-3B, yes. It takes a few minutes and saves interest. If the mistake runs across months, or you have already filed GSTR-3B, it needs the later amendment route, and our guide on rectifying GSTR-3B is the next step.

Frequently asked questions

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