I believe you will not be taxed on earnings in Australia since it is not yet your tax residence. However, should you need any assistance from Centrelink (unemployment assistance, etc..) your earnings for the financial year will take Qatar income into consideration.

Foreign income
Australian residents are taxed on their worldwide income so you must declare all foreign-source income in your tax return.

Also, any tax you are currently paying will be taken into consideration.

Have a look at this website to give you some info on whether you will be considered resident or not. It depends on visa you use when you come to Australia. You may ask those questions to ATO on line.