David, I have yet to find a definitive statement from the ATO saying that you cannot be both. Many people have stated on HC and other forums that on contacting the ATO, they have been told that so long as there is clear separation of trading activities from investing activities (ie. 2 different accounts) then you will be OK.
When I first started trading I was told by my accountant that you cannot be both so he suggested setting up a company for trading, which I did. But in the meantime I have seen statements (none as I say definitive) that you can be both so long as you can show the ATO there is a separation. I still use the company for trading, as it has other advantages.
