You have an option to suspend a form until you are ready to lodge it.
To track suspended forms -
Navigate to Dashboard , select "Completed". *if the form was suspended after sending for signing, select "To Lodge".
Filter by Form Type.
Look for the clock symbol.
You will not able to lodge a tax return until it is unsuspended. (Manual press "Unsuspend" to proceed with lodgement).
Please note that it doesn't change ATO due date.