You cannot revise a return once filed under GST. However, you can rectify the mistake made in the return in the GSTR-1 filed for the next period (month/quarter)1. This means that if you made a mistake in GSTR-1 of November 2023, you can rectify it in the GSTR-1 of December 2023 or subsequent months2. You can also download the GSTR-1 return file from the GST portal and use the offline tool to modify, add, or delete the invoice details uploaded earlier3. After making the necessary changes, you have to prepare a JSON file for regular invoice data and upload it on the GST portal3