A Director Penalty Notice is the ATO’s way of holding you personally liable for...

https://uniform-wiki.win/index.php/The_DPN_Trap:_Why_Your_Mailroom_Isn%27t_Your_Calendar

A Director Penalty Notice is the ATO’s way of holding you personally liable for company tax debts like PAYG, GST, and SGC. The 21-day clock is non-negotiable and starts from the date on the notice