This is how shared physical care is calculated under the Illinois Income Shares model:
(1) this calculation only applies if both parties have at least 146 overnights with the minor children. Anything less than 146 will not change the basic calculation of an obligor’s child support obligation.
(2) the Basic Child Support Obligation which is determined from the income share schedule is multiplied by 1.5 to calculate the Shared Care Child Support Obligation.
(3) each parent’s share of the combined net income is determined.
(4) A parent’s share of the Shared Care Child Support Obligation is then computed for each parent by multiplying the Shared Care Child Support Obligation with the Percentage Share of Combined Net Income for that parent.
(5) The Percentage of Overnights is calculated for each party by dividing the total number of overnights a parent has with the child(ren) by the total number of overnights in a year (365 or 366).
(6) That each parent’s portion of the Shared Care Child Support Obligation is then multiplied with the Percentage of Overnights of the other parent.
(7) The respective child support obligations are offset with the parent owing more child support paying the difference between the two amounts.
The major difference between a basic income shares calculation and a shared physical care calculation is that the respective obligations of the parties are offset. As a result, in circumstances where the parties’ income are similar, a shared physical care calculation would result in a nominal child support obligation.