Many business operate under a company structure. Some companies have the ABN linked direct to the company. Other companies have the ABN linked to a trust if the the company is a trustee for the trust (often written as "ABC Pty Ltd in trust for XYZ Trust" or "ABC Pty Ltd as trustee for XYZ Trust").

Operating as a company means that the owner may seperate himself and his personal assets from his role as director. This is referred to as operating within the corporate veil. However, if the director does not operate within the laws placed on the director (operating outside the the corporate viel) then the director and his personal assets become exposed.

However, these days most financial institutions and suppliers require directors to sign a personal guarentee, which removes the personal financial protection that the director would otherwise have.