One parent is absent and the other is treated as absent
21.—(1) Where the circumstances of a case are that one parent is an absent parent and the other parent is treated as an absent parent by regulation 20(2), that case shall be treated as a special case for the purposes of the Act.
(2) For the purpose of assessing the child support maintenance payable by an absent parent where this case applies, each reference in Schedule 1 to the Act to a parent who is a person with care shall be treated as a reference to a person who is treated as an absent parent by regulation 20(2).