The Mark as Cancelled option will only be visible 24 hours after the IRN is generated for the transaction. During the 24 hour window, the Cancel e-Invoice option will be visible.
You can find the date and time when the IRN was generated from the Ack Date field located at the footer for the transaction’s PDF. Here’s how:
The Ack Date field at the footer of the transaction’s PDF will contain the date and time when the IRN was generated for the transaction.
and GST filing.