The New Illinois Child Support Guidelines

The law change

  • Effective July 1, 2017, Illinois will begin calculating child support in a new way. Illinois will join 40 other states in using an “Income Shares” method for calculating child support.

The current way

  • Illinois currently uses a “Percentage of Net Income” method for calculating child support. This is a pretty straightforward calculation.  The relevant statute contains a table of percentages.  The more children that are being supported, the higher the percentage of the supporting parent’s net income is paid as child support.
  • There are rules for what counts as net income. For example, prior court ordered child support obligations reduce net income.
  • The current table of support has percentages as follows: 1 child, 20%; 2 children, 28%; 3 children, 32%; 4 children, 40%; 5 children, 45%; and 6 or more children, 50%.
  • For example, if a father is obligated to pay support to the mother of his 2 children and he has a net income of $4000.00 per month, he needs to pay $1120.00 per month in child support. (4000 x 0.28 = 1120)
  • This is a basic child support amount. Under the current law, the court may order additional amounts for things like extra-curricular activities, child care and educational expenses.
  • Only the supporting parent’s income matters under this method.
  • Parenting time doesn’t affect the calculation. Even if the children spend 45% of the time with the father, the current guidelines still result in the same child support amount.

The new way


  • The new child support guidelines will follow the “Income Shares” method. This method is quite different from the current method.
  • Under the new method, both parents’ incomes are factored into the calculation.
  • The Illinois Department of Healthcare and Family Services (HFS) will be providing a table that sets forth the amount of income that would be used to support the children if the mother and father were living together. This amount will vary depending on the number of children and the parents’ total income.
  • Each parent’s share of the total income determines what that parent should pay for child support. The custodial parent is considered to pay his or her share just by having the children for the majority of the time. The other parent must pay his or her share of the child support to the parent that has the children most of the time.
  •  If the parents share or nearly share parenting time, a further calculation needs to be made to adjust the amount of child support.
  • Net income amount is calculated based on the individual’s gross income as adjusted by schedules the state will provide.
  • Like the current method, additional items such as child care expenses, extra-curricular activity costs and other items may be added to the base amount of support.

An Example

  • An example might clarify. Unfortunately, HFS has not provided the tables yet, so this is an example based on tables used in Iowa.  (Here is a link to the Iowa Child Support Table.) Obviously, this example will not be accurate for Illinois. We can’t do the actual Illinois calculations until HFS provides the Illinois tables.
  • There are essentially three steps to calculating child support under the new method:
    • Step 1: Figure out the total net income of the parties.
    • Step 2: Look up the amount of total child support from the table.
    • Step 3: Determine what each parent’s share of the total support is.
  • Let’s keep the numbers simple. Mother makes $100,000 net income per year and father makes $50,000 net income per year. They have two children together.
  • The first step is combining the parents’ net incomes. The combined net incomes here is just $100,000 + $50,000 = $150,000. The total net monthly income of the couple together is $150,000/12 which is $12,500.
  • The second step is figuring out how much total child support is needed to support two children in a household with a net monthly income of $12,500. This is where the HFS tables come in. According to the current Iowa table, the amount of support that two children are entitled to at that income level is $2395 per month. This is the total support amount.
  • The third step is calculating what percentage of the total support amount each party is responsible for. We need to figure what each party earns as a percentage of the total income.
  • In this case, the father earns $50,000/$150,000 = 0.33 or 33% of the total income. The mother earns $100,000/$150,000 = 0.67 or 67% of the total income.
  • The father is responsible for 0.33 x $2395 = $790.35 per month. The mother is responsible for 0.67 x $2395 = $1604.65 per month.
  • Who pays what? This depends on the allocation of parenting time.
    • If the children clearly spend the majority of their overnights with the mother, then the father would pay her the $790.35 per month.
    • If the children clearly spend the majority of their overnights with the father, then the mother would pay him the $1604.65 per month.
    • If the children spend close to an equal number of overnights with each parent, another calculation needs to be done. The amount going from one parent to the other will be reduced. I will leave this calculation to another post.


A change in the law such as this might be confusing for people that have current child support orders. Nothing should change about current child support unless there has been a substantial change in circumstances. If you have any questions about child support, feel free to contact us for a consultation.  Contact Us


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