Income tax  in Australia is levied upon three sources of income for individual taxpayers:  personal income which includes salary and wage; business income and also capital gain.  

Income received by individuals is taxed at progressive rates from 0 to 45%, plus a medical levy of up to 2%, while income derived by companies is taxed at a flat rate of either 30% or 27.5% depending on annual turnover. Generally, capital gains are only subject to tax at the time the gain is realised. Capital gains are also reduced by 50% if the asset sold to create the capital gains tax event was held for more than 1 year. Income tax is collected by the Australian Taxation office. 

 the Australian financial year ends on the 30th of June. 

sources: https://www.taxback.com/blog/australia-key-tax-dates

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