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

https://alpha-wiki.win/index.php/Does_the_ATO_Still_Show_Leniency_on_Tax_Debts_Like_It_Used_To%3F

A Director Penalty Notice is the ATO’s way of holding you personally liable for company PAYG, GST, and SGC debts. The 21-day clock starts the moment it is issued, so do not ignore it