Filed GSTR-1 and then noticed a missed invoice or an incorrect outward-supply detail? GSTR-1A is an optional way to add or amend records for that same tax period before you file its GSTR-3B. It gives a regular taxpayer a chance to correct the period’s outward-supply statement after GSTR-1 has been furnished.
The timing matters: GSTR-1A is available from the later of the GSTR-1 filing date and its due date, and it closes when GSTR-3B for that same period is filed. The GST Portal says it can be filed only once for a tax period. Check the current portal instructions for the relevant period before acting.
What GSTR-1A does
GSTR-1 is the supplier’s statement of outward supplies. GSTR-1A is an amendment facility for the same period’s GSTR-1: a taxpayer can add a missed supply record or amend a record already furnished for that period. The corrected details are then auto-populated in that period’s GSTR-3B, which the taxpayer still has to review and file separately.
For a step-by-step explanation of the main sales return, see our GSTR-1 filing guide. This article focuses on the correction window after GSTR-1 has been filed.
When does GSTR-1A open and close?
The GST Portal’s GSTR-1 guide describes the window this way:
- It opens on the later of the actual GSTR-1 filing date or that period’s GSTR-1 due date.
- It closes when GSTR-3B for the same tax period is filed.
- It is optional and may be filed only once for a particular tax period.
There is no separate fixed calendar due date for filing GSTR-1A. Its practical deadline is the filing of the same period’s GSTR-3B. Ordinary GSTR-1 and GSTR-3B deadlines can vary by taxpayer, period, or government notification; check the GST Portal for the date that applies to you.
Example: If a monthly taxpayer files GSTR-1 before its due date, GSTR-1A does not open until that due date. The taxpayer can then use the facility until filing GSTR-3B for that month. If GSTR-1 is filed after its due date, the later filing date controls when GSTR-1A becomes available.
What can you correct?
Use GSTR-1A when a detail in the same period’s outward-supply reporting needs to be added or corrected and the facility is open. Examples include:
- A sales invoice for the period was accidentally left out of GSTR-1.
- A reported invoice contains a data-entry error that should be corrected against the original business record.
- The reported taxable value or tax details need correction because the filed return does not match the underlying transaction documents.
Keep the invoice, contract, credit or debit note, and accounting entry available while checking a correction. A reporting correction does not change the underlying commercial document by itself. If the transaction itself changed after supply, determine whether a credit note, debit note, or another document is legally appropriate; do not use a return amendment as a substitute for that document.
How to use the GSTR-1A window
The exact portal labels can change, so follow the current GST Portal instructions for your return period. A careful review usually looks like this:
- Reconcile your outward supplies. Compare the filed GSTR-1 with your sales register, invoices, amendments, and notes for the same period. List each record that is missing or incorrect.
- Confirm the period and window. Check that GSTR-1A is available for the correct month or quarter and that GSTR-3B for that period has not already been filed.
- Prepare the correction from source documents. Verify the recipient GSTIN, invoice number and date, place of supply, taxable value, tax rate, and tax amounts against your records. Do not change a tax classification only to make the return totals match.
- Add or amend the eligible record in GSTR-1A. Review the portal’s validation messages and the updated summary before proceeding. This is a return correction workflow; Taxzentic does not file or amend returns on your behalf.
- Check the GSTR-3B preview. The GST Portal says GSTR-1A changes are auto-populated in GSTR-3B for the same period. Confirm that the corrected liability appears as expected, then complete your normal GSTR-3B review and filing.
- Save an audit trail. Keep the original and corrected data, supporting documents, portal acknowledgement, and a brief note explaining the change.
If an offline GSTR-1 upload was rejected, first understand the portal’s error report and correct the source data; our GST Error Report Decoder can help make a downloaded GSTR-1 error JSON easier to read. It does not submit GSTR-1A or connect to the GST Portal.
What happens to the buyer’s GSTR-2B?
The seller’s correction and the buyer’s ITC statement do not necessarily appear in the same period. The GST Portal FAQ says supplies added or amended through GSTR-1A are reflected in the recipient’s GSTR-2B for the next tax period. The buyer should check that later statement and reconcile it with the invoice and other ITC conditions before claiming credit.
Buyers can compare portal data with their purchase register using the GSTR-2B reconciliation tool. It supports a manual reconciliation workflow; it does not determine legal ITC eligibility or access GST Portal records.
If GSTR-3B has already been filed
Once GSTR-3B for a period is filed, GSTR-1A for that same period is no longer available. The GST Portal FAQ says the existing facility to amend eligible earlier-period records in a subsequent GSTR-1 continues. The amendment tables, applicable time limits, and treatment depend on the record and current law, so verify the portal guidance before making a later-period correction or ask a GST professional.
Do not file a duplicate invoice just to force a mismatch to clear. First confirm whether the record was omitted, reported under another table, amended already, or belongs to a different period. If you need to create a new invoice document, our GST Invoice Draft Generator can prepare a draft for review; it does not decide the correct return treatment.
GSTR-1A FAQs
Is GSTR-1A mandatory?
No. The GST Portal describes it as an optional facility. Use it when you need to add or amend eligible outward-supply details for the same tax period and the window is open.
Can I file GSTR-1A more than once for a month or quarter?
No. The portal guidance says GSTR-1A can be filed only once for a particular tax period. Prepare and review the complete correction list before filing it.
Can I file GSTR-1A after filing GSTR-3B?
No. It closes when GSTR-3B for that same period is filed. For eligible earlier-period corrections, check the amendment facility in a subsequent GSTR-1 and the applicable statutory time limit.
Does GSTR-1A replace GSTR-1 or GSTR-3B?
No. It is an optional correction step for that period’s GSTR-1. It does not replace either return, and you still need to review and file GSTR-3B.
Does GSTR-1A have its own due date?
The GST Portal FAQ says there is no separate fixed due date. The window remains available only until GSTR-3B for that period is filed. This does not extend the due dates for GSTR-1 or GSTR-3B.
When will a GSTR-1A correction appear in the buyer’s GSTR-2B?
According to the GST Portal FAQ, the recipient sees supplies added or amended through GSTR-1A in GSTR-2B for the next tax period. The buyer should verify the relevant statement and other ITC conditions.
Does GSTR-1A automatically file my GSTR-3B?
No. Its changes are auto-populated in the same period’s GSTR-3B, but the taxpayer must review and file GSTR-3B separately.
Can I use GSTR-1A if the same-period GSTR-3B is already filed?
No. That GSTR-1A window has closed. Check the GST Portal’s current amendment guidance for the appropriate later-period route.
Official references
This guide explains the GST Portal’s published workflow; it is not tax advice and does not determine how a specific transaction should be reported. Portal steps and legal requirements can change. Verify the current instructions for your tax period or consult a qualified GST professional before filing.