(1) For any period when 2 individuals who are members of a couple would otherwise be eligible at the same time for family tax benefit in respect of one or more FTB children or regular care children, only one member is eligible.
(2) The member who is eligible is the one determined by the Secretary to be eligible, having regard to:
(a) whether one member of the couple is the primary carer for the child or children; and
(b) whether the members have made a written agreement nominating one of them as the member who can make a claim under Part 3 of the A New Tax System (Family Assistance) (Administration) Act 1999 for payment of family tax benefit in respect of the child or children.