Income tax is budgeted to raise $218 billion in 2018-19, and $954 billion over the forward estimates. It is by far our largest and most important tax.
Income tax represents 46% of all Commonwealth revenue in 2018-19, and 11.5% of GDP.
The model allows you to make changes to the basic parameters that drive income tax collections:
The finer details of some of these rates and thresholds (such as the differences in the Low Income Tax Offset between family types, and the Seniors and Pensioners Tax Offset) are not modelled. In these cases a representative average has been used for modeling purposes.
Currently income tax thresholds are not indexed (i.e. adjusted for inflation) which gives rise to the phenomenon known as ‘bracket creep’. Higher income over time results in more people moving into higher marginal tax brackets. The model allows you to:
The Medicare related thresholds are routinely adjusted by the consumer price index. As with the income tax thresholds you can choose whether and how to index these thresholds.
The default position – as with all other aspects of the model – is the currently legislated arrangements.
The model shows the first order direct effects of the changes to current income tax provisions. It does not examine or assume any second round effects, such as the impact of changes to company tax (and therefore franking credits) beyond those already proposed by the Government in its 2018-19 Budget, or the impact of changes to the definition of ‘income’ or ‘taxable income’. These may be examined in future releases.