5.—(1) The assessable income of an absent parent shall be calculated by applying the formula—
A = N - E
where—
A is the amount of that parent’s assessable income;
N is the amount of that parent’s net income, calculated or estimated in accordance with regulations made by the Department for the purposes of this sub-paragraph; and
E is the amount of that parent’s exempt income, calculated or estimated in accordance with regulations made by the Department for those purposes.
(2) The assessable income of a parent who is a person with care of the qualifying child or children shall be calculated by applying the formula—
C = M - F
where—
C is the amount of that parent’s assessable income;
M is the amount of that parent’s net income, calculated or estimated in accordance with regulations made by the Department for the purposes of this sub-paragraph; and
F is the amount of that parent’s exempt income, calculated or estimated in accordance with regulations made by the Department for those purposes.
(3) Where the preceding provisions of this paragraph would otherwise result in a person’s assessable income being taken to be a negative amount his assessable income shall be taken to be nil.
(4) Where income support or any other benefit of a prescribed kind is paid to or in respect of a parent who is an absent parent or a person with care that parent shall, for the purposes of this Schedule, be taken to have no assessable income.