Many assumptions here.
What is your employer - employee contractual arrangement. If you are a typical employee and are subject to PAYG then forget it.
If you are some form of contractor who has use a coy and trust as a vehicle then it is possible.
However, if you are considering taking the risk for a measly $20k AUD then suggest not to consider.
There are far more legally grey ways of offsetting taxable income through a corporate entity. Be aware the avoidance provisions and personal services legislation in the Income Tax Assessment Act are severe so make it worth your while.
I have a friend who did the following:
* Created a discretionary trust
* Purchased a shelf company
* Spent his 2 years income and did not remit tax or GST to the ATO.
* Accrued a tax bill of $300k AUD.
* Purchased a clean company "Enron Inc" with existing debt in excess of his acrrued tax liability at 5 cents in the dollar
* Directed the income via the trust to "Enron inc" which with the losses offset the income.
He ended up with a tax refund.
Play by the rules and end up poor. I used to be in tax law in my younger years and this is nothing compared to what the Top 1000 richest in Australia.
Suggest you find a way to become self employed and use legal loopholes too reduce your tax liability and earning potential.