(1) This section reduces your * GST instalment shortfall, for a * GST instalment quarter of an * instalment tax period applying to you, if:
(a) you pay to the Commissioner a * GST instalment for a later GST instalment quarter of the instalment tax period; and
(b) that GST instalment exceeds 25% of your * annual GST liability for the instalment tax period.
The amount of that excess is called the top up .
(2) The * GST instalment shortfall is reduced by applying so much of the top up as does not exceed the GST instalment shortfall.
(3) However, if some of the top up has already been applied (under any other application or applications of this section) to reduce a * GST instalment shortfall for a different * GST instalment quarter of the * instalment tax period, the GST instalment shortfall is reduced by applying so much of the top up as has not already been applied, and does not exceed the GST instalment shortfall.
(4) The reduction under subsection (2) has effect for each day in the period that:
(a) started at the beginning of the day on which you paid the * GST instalment for the later * GST instalment quarter; and
(b) finishes at the end of the day before which you must, under section 162-110, pay to the Commissioner your * assessed net amount for the * instalment tax period.