Thanks for your informative replys Mr J and Dan. I am of the opinion that a "winning" punter cant be taxed because If this were the case then the 90+% of losing punters would then have a case to claim losses.

I also believe that I contribute my taxes with the TAB's Takeout and the turnover tax of the corporate bookmakers I place bets with. If I was ever pulled up I would say I was just having a lucky run, which i might be. But how long does a lucky run last for and how long can one not have a "real" job before the ATO become suspicious?