If:
(a) the Secretary or a person's employer (the payer ) becomes required to pay an instalment to the person in relation to a child of the person after the start of the person's continuous flexible period for the child; and
(b) neither the Secretary nor the employer is otherwise required to pay an earlier instalment to the person; and
(c) one or more instalments would have been payable to the person on the paydays for the instalments if the payer had been required to pay instalments from the start of the person's continuous flexible period for the child;
then the instalments referred to in paragraph (c) are taken to have become payable on the respective paydays for the instalments.