Supreme Court of Missouri
en banc

 (12) With respect to the adjustment for a portion of amounts expended by the parent paying support during periods of overnight visitation or custody:

The basic child support amount can be divided into three categories of expenditures:

Variable expenditures are child-related expenditures that vary directly with the amount of time a child spends with each parent, such as food.  It has been assumed that variable expenditures represent 38% of the basic child support amount.
Duplicated fixed expenditures are child-related expenditures that do not vary with the amount of time a child spends with each parent but are incurred by both parents, such as housing.  It has been assumed that duplicated fixed expenditures represent 30% of the basic child support amount.

Non-duplicated fixed expenditures are child-related expenditures that do not vary with the amount of time a child spends with each parent and are usually incurred by the parent in whose household a child resides the greater amount of the time, such as clothing.  It has been assumed that non-duplicated fixed expenditures represent 32% of the basic child support amount.
The amount of any adjustment to which the parent obligated to pay support is entitled for a portion of the amounts expended on the children who are the subject of this proceeding during periods of overnight visitation or custody assumes that the parent obligated to pay support will incur:

(1) no significant expenditures for the children if that parent exercises visitation or custody for less than 36 periods per year;

(2) variable expenditures for the children if that parent exercises visitation or custody for 36 or more periods per year;

(3) duplicated fixed expenditures for the children if that parent exercises visitation or custody for 110 or more overnight periods per year; and

(4) no significant non-duplicated fixed expenditures for the children.