The amount of levy that a person is liable to pay under section 154 - 16, in respect of an * income year, is an amount equal to the difference between:
(a) the amount that the person would have been liable to pay under section 154 - 1 if:
(i) the person had a * repayment income for the income year of an amount equal to the person's * assessed worldwide income for the income year; and
(ii) subsection 154 - 1(2) did not apply to the person; and
(b) the amount (if any) the person is liable to pay under section 154 - 1, in respect of the income year.