When a Director Penalty Notice arrives, the 21-day clock starts immediately....

https://www.accountantsdaily.com.au/regulation/22264-2026-dpn-surge-why-early-intervention-beats-the-21-day-clock

When a Director Penalty Notice arrives, the 21-day clock starts immediately. Ignoring it is risky because once that deadline passes, the ATO can pursue your personal assets for company tax debts like PAYG, GST, and SGC