A Director Penalty Notice is the ATO’s final warning. The 21-day clock starts...

https://www.red-bookmarks.win/when-you-receive-a-director-penalty-notice-the-21-day-clock-starts-ticking

A Director Penalty Notice is the ATO’s final warning. The 21-day clock starts the moment it is issued, not when you open the mail. If your PAYG, GST, or SGC returns aren’t lodged, you face a lockdown DPN, making you personally liable for the debt