If you receive a Director Penalty Notice, don’t wait. The 21-day clock starts...

https://www.emergbook.win/when-an-ato-director-penalty-notice-arrives-the-21-day-clock-starts-ticking-1

If you receive a Director Penalty Notice, don’t wait. The 21-day clock starts the moment it is issued, not when you open it. If your PAYG, GST, or SGC returns aren’t lodged within three months of the due date, you face a lockdown penalty