GSTR-1A is a document reflecting modifications made to sales invoices originally reported in GSTR-1. It enables registered taxpayers to amend the details of sales data previously filed in their GSTR-1 returns.
The GSTR-1A can be prepared and submitted prior to filing the GSTR-3B return.

Step 1: Navigate to the "GSTR-1A Prepare" option in the Return Summary.

      

Step 2: Select the "View/Edit Data" option to review and modify the necessary details.

      
Step 3: Make the required amendments and confirm the changes.

      

Step 4: Once all changes have been made, click "Save Data on Portal" to upload the updated return to the GSTN.

      
Step 5: After successfully uploading the return, proceed to "File GSTR-1A (EVC/DSC)" to complete the filing process by selecting the appropriate verification option.

      

By following these steps, you can file your GSTR-1A return successfully.