Illinois Child Support

How Child Support is Calculated in Illinois

In July, 2017, Illinois became an “income shares” state.  This means that both parents’ incomes are used to calculate child support. Economists have developed a series of tables that determine how much two parents spend on a child or children depending on their combined net income. From that figure, the partiers’ respective percentages of the total net income are applied to the total amount. The result is the amount of support paid. There is an additional provision that if a parent has at least 146 overnights a year, support can be reduced. These are still guidelines and thus a Judge has the right to deviate from these numbers.

There are two ways to reach net income. The first is to use a simplified tax amount and is based on a standard formula. This is simpler than the second method but does not always reflect the actual net income of the parents.

The method by which net income is reached is to use the actual individual tax amount paid by each parent. This is a fairer representation of the net income available to each parent. Fortunately, we are able to use software programs specifically developed for this purpose, making the calculations far more simple than they would have been were it being done “by hand.”


Maintenance is always calculated first.  Then it is applied in the support calculation. Thus, if you are the spouse receiving maintenance, that amount of money will be added into your net income. That amount will be subtracted from the other spouse’s net income. Then child support is calculated.

In addition, child support being paid on behalf of another family is also deducted from gross income to reach net income. The amount to be deducted depends on whether the support is paid as a result of a court order or on a voluntary basis. This deduction is applied after taxes are deducted.

Child Care Expenses

Child care expenses are determined separately from child support. One or both parents may be required to contribute to school and extracurricular expenses. A court can also enter orders regarding medical expenses and health insurance.

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