(1) Your notified instalment amount for a * GST instalment quarter is the amount that is:
(a) worked out by the Commissioner; and
(b) notified by the Commissioner to you before the day on which the * GST instalment is due.
The amount must not be less than zero.
(2) However, the Commissioner is not to work out or notify a * notified instalment amount for a * GST instalment quarter if you had a * varied instalment amount for an earlier GST instalment quarter of the same * instalment tax period.