If you do not have a income from regular job, then you start...

If you do not have a income from regular job, then you start with tax bracket is "zero percent", what ever you earn now will start the counter.

1. If you have CGT from day trading or in general trading then whatever money you earn will determine your tax bracket and tax payable to government

2. If you have got dividends say FMG pays 100 percent franking dividends , that means FMG has already paid 30 percent on your behalf and you can claim this .

Scenario 1 - if your dividend income come under 30 percent tax bracket, then NO TAX
Scenario 2 - If your dividend income comes above 30 percent tax bracker, pay the rest (minus 30 percent)