(1) The determination, or a variation of the determination, has effect, or is taken to have had effect, on and from:
(a) the day specified in the notice as the day on which the determination or variation takes effect, or took effect; or
(b) if a day is not specified--the day on which the notice is given.
(2) The determination ceases to have effect at the end of the earliest day on which one or more of these occurs:
(a) one or more conditions to which the determination is subject are not met;
(b) the Commissioner revokes the determination;
(c) the period for which the determination has effect comes to an end.