Receiving a DPN is a critical moment for any SME client. Crucially, the 21-day...
https://web-wiki.win/index.php/DPN_Triage:_What_documents_do_you_need_when_the_ATO_comes_knocking%3F
Receiving a DPN is a critical moment for any SME client. Crucially, the 21-day clock starts from the issue date, not the date of receipt