All good advice above, if you go to the ATO website there is a basic 4 questions (I think) to ascertain if you will be a resident for tax purposes, having a wife and/or kids in Australia will almost certainly qualify you for that. As someone suggested, if you want to be 99% sure (you'll never be 100%),get a ruling from the ATO. I don't know anything about the US tax system but you may well be better off paying Australian tax?