Dion is a qualified accountant and a Member of the Institute of Chartered Accountants (CA). He is currently a Director and co-owner of Bonsella Business Solutions, a local chartered accounting practice that has been operating since 2003. Dion holds a Bachelor of Commerce (ANU) and also a Certificate of Public Practice through the Institute of Chartered Accountants. He is also an ASIC-registered self-managed superannuation fund auditor. He is past Treasurer of Soccer Canberra (now Capital Football) and is married with two daughters.