A proprietary company is a form of privately held company in Australia and South Africa that is either limited or unlimited. However, unlike a public company there are, depending on jurisdiction, restrictions on what it can and cannot do.In Australia, a proprietary company is defined under section 45A(1) of the Corporations Act 2001 (Cth).The Act puts certain restrictions on proprietary companies such as not permitting them to have more than 50 members (shareholders). Another important restriction relates to fundraising.owever, unlike a public company there are, depending on jurisdiction, restrictions on what it can and cannot do. In Australia, a proprietary company is defined under section 45A(1) of the Corporations Act 2001 (Cth).