By Andrew Mackinnon
As far as I can tell, the number of Australian citizens who submit a tax return in Australia is currently about 13 million and the average taxable income declared on these tax returns is about $65,000.
If there was only income tax in Australia at a flat rate of a maximum of 20% on all income earned, then the maximum taxation revenue the Australian federal government would raise in one year is 13 million x $65,000 x 0.20, which equals $169,000 million or $169 billion.