The ‘au Domain Administration‘ (auDA) have regulations for who can register an Australian Domain.
The .com.au or .net.au domains can only be registered to Australian sole traders, businesses or companies. You will need to provide either an ABN, ACN, State Business Number, Trademark Number or Incorporated Association Number when going through the registration process.
Only Australian non-profit organisations and registered charities can register a .org.au domain.
Australian associations, clubs, sporting groups, political parties and close equivalents may register a .asn.au domain names, however associations must be nonprofit.