From the Customs website:
Migrant Concessions
As a first-time migrant or returning Australian resident, you are entitled to bring back with you to Australia, duty and GST free, all your personal and household effects that you have owned and used for the whole of the period of 12 months immediately preceding your departure for Australia.
Certain items are expressly excluded from the definition of "personal and household effects" and are subject to other requirements. These include:
- motor vehicles or motor vehicle parts
- caravans, boats and trailers
- aircraft
- machinery, plant and equipment
- and fur apparel.