How do I mark GSTR-1 as filed?

Quick answerIn 2 steps

After filing on the portal, open Reports → GST returns for that month and press “Mark GSTR1 filed…”.
Type the ARN and press “Mark filed”. It cannot be undone: that month's bills can then be corrected only with credit notes.

WhereReports → GST returns in the back office

Learn it properlyRecord that a return was filed (ARN) to lock the periodAfter filing on the portal, lock the month so its bills cannot change.Open the lesson →

Also asked as

“record the ARN”
“lock a GST period”