For 2017/18, a rule for calculating the tax on eligible taxable income where the minor is a resident is as follows (Income Tax Rates Act 1986 (ITRA), s 13; Sch 11):

"(2)If the eligible taxable income exceeds $416 but does not exceed $ 1307, the tax on the eligible taxable income is the greater of:(a)66% of the excess over $416, and(b)the difference between tax on the whole of the taxable income and tax on the taxable income that does not qualify as eligible taxable income."

Critically discuss what is intended by employing the word "tax" in rule 2 (b) here above? Your answer should attempt to define the concept of "tax" for the purpose of calculatingthe tax on the eligible taxable income.