Capital Gains - Tax, page-24

Yes, I should have mentioned this. I would also add that it would be a lot easier to for a punter to effectively differentiate between their trading activities and their investing activities (talking about shares only, here) if the "investments" were held for longer than 12 months. I cannot imagine ATO recognizing a punter as a share "trader" for one set of completed share transactions on the one hand and then as a share "investor" for another set of completed share transactions on the other hand (i.e. in the same tax year) without some kind of compelling reason. Remember, a punter has to jump through a number of hoops to satisfy the ATO of their "share trader" status. Undoing that and reverting back to the default "share investor" status for a concurrent set of share transactions is no small feat without an accompanying compelling rationale. Having held the "investment" shares for longer than 12 months (i.e. purchased in a different tax year) and using a different broker would certainly go a long way to proving those bona fides. If those "investment" shares have been held for several years, all the better.

Coming back to bellenuit's specific personal situation, I think that simply adding CFDs to the mix, using the same broker (you implied you are using IB) wouldn't be a problem, as CFDs are a different instrument.