GSTR-1A explained: correcting your GSTR-1 in the same period

Why GSTR-1A was introduced

Earlier, a mistake noticed after filing GSTR-1 could only be fixed in the next period's GSTR-1, while the correct figure was simply typed into GSTR-3B. With the output liability tables of GSTR-3B now drawn from GSTR-1 and not editable, a mismatch would otherwise lead to wrong tax payment for the month.

Rule 59(4A) of the CGST Rules provides for GSTR-1A, and the facility has been available on the portal since the July 2024 tax period.

When you can file it

• Only after GSTR-1 (or the quarterly GSTR-1 for QRMP taxpayers) for that period has been filed
• Only until GSTR-3B for the same period is filed; once GSTR-3B is filed, the window closes
• It is optional and filed only when there is something to add or correct
• It can be filed once for a tax period

What it changes

You can report invoices, credit notes and debit notes you missed, and amend records already reported in the GSTR-1 of the same period, such as a wrong taxable value, wrong tax head or wrong buyer GSTIN. The revised figures flow into GSTR-3B immediately, so the tax you pay matches the corrected position.

For buyers, records added or changed through GSTR-1A appear in their GSTR-2A and are taken into a later GSTR-2B, not the one already generated. If a correction affects a customer's credit, tell them so they can expect it in the next cycle.

Practical tips

Reconcile your sales register with the filed GSTR-1 as soon as it is filed, not on the GSTR-3B due date. Treat GSTR-1A as the last checkpoint before the liability is fixed. If you miss the window, the only route is an amendment in a subsequent GSTR-1, with tax and interest adjusted in that later GSTR-3B.

A reviewer who compares GSTR-1 with your books each month can catch errors early enough to use GSTR-1A instead of carrying them into later periods.

Get it handled for you

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This guide explains the law in general terms as of October 2026. Time limits and requirements can depend on the facts of your case and on the notice you received.