If the Secretary makes a determination under section 78 (rate increase determination) as a result of a review required by section 126A (review of determination of youth allowance rate in relation to maintenance income), the determination takes effect:
(a) unless paragraph (b) applies--on the date that would give full effect to the decision on review; or
(b) if the date referred to in paragraph (a) is earlier than the first day of the income year before the income year in which the review decision was made--that first day.