The ATO has estimated that the net “tax gap” for individuals not in business in 2014–2015 is approximately 6.4%, or $8.8 billion. The gap is an estimate of the difference between the tax the ATO collects and the amount that would have been collected if every one of these taxpayers was fully compliant with the law.
In other words, the ATO estimates that individuals not in business paid over 93% of the total theoretical tax payable in 2014–2015.