New Changes to Illinois Child Support Laws in 2017


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New Changes to Illinois Child Support Laws in 2017

New changes have come to Illinois child support laws, effective July 1st, 2017.   Child support will be calculated by an entirely different method than what had been used for the past 30 years.


Update: A new Child Support Calculator has been released by the Illinois Department of Healthcare and Family Services.  Click here for links to the estimator.  Please note that this child support calculator only provides estimates of what the child support payments may be.  The resulting calculations may differ from what is actually established by the court in a child support case.


Old Law

Illinois child support law has traditionally been calculated by taking the payor’s net income (gross income, minus taxes and other deductions), and applying a certain percentage based on the number of minor children, for example:

One minor child:  20% of net income

Two minor children: 28% of net income

Three children: 32% of net income


New Law

Under the new Illinois child support law in 2017, both parents incomes will be considered when calculating support.   That is, child support will be calculated based on the combined net incomes of both parents.  The old method of using flat percentages based on the number of children will no longer be used.  Instead, child support will be calculated as follows:

  1. Determine each parent’s “net income” by running their gross incomes through a gross to net conversion chart.
  2. Combine both parents’ net incomes to determine the combined net income.
  3. Determine what percentages of the combined net income is represented by each parent’s net incomes.
  4. The combined net income from step 2 will be plugged into an income shares chart to determine the basic child support obligation. 
  5. Multiply the resulting number from step 4 with the percentages from step 3, for each parent.
  6. The resulting numbers are each parent’s child support obligations.  The number for the non-paying parent, typically the parent with the majority of parenting time, will be presumed to already be applied to the child.  The number for the paying parent will be that parent’s child support obligation, and must be paid to the non-paying parent.


Here is a basic example of how the new process can work.  In this example, the parties have one child, Mother has the majority of parenting time, and Father is paying the child support obligation:

  1. Father’s gross income is $3,000 monthly, which applied through the gross to net conversion chart results in a net income of $2,384.  Mother’s gross monthly income is $7,000, which when applied to the same chart results in a net income of $5,122.
  2. Calculate the combined net income of both parents: $2,384 + $5,122 = $7,506.
  3. Father’s percentage of the combined net income is 32%, Mother’s percentage of combined net income is 68%
  4. The combined net income amount from step 2 ($7,506) is then plugged into the income shares chart, resulting in a basic child support obligation of $1,201, for one child.
  5. The resulting number from the chart, $1,201, is then multiplied by 32% for Father, and by 68% for mother.  This results in $384.32 for Father, and $816.68 for Mother.
  6. In this example, Father will pay $384.32 per month to Mother.  The resulting number above for Mother, $816.68, is assumed to be used by her in every day expenditures for the child.

*Please note that this is a basic example for illustration purposes only.  The income levels used here will not necessarily result in the child support amount shown above.  Other factors can be taken into consideration.

As you can see, calculation under the new law will be a bit more complex than the previous child support model. 


More Changes

  • If a parent is currently paying court-ordered child support in a separate and unrelated case, the amount of child support being paid in that other case will be deducted from that parent’s gross income, for determining net income.
  • If one parent is paying maintenance (“alimony”) to the other, the maintenance payment is subtracted from the paying parent’s gross income, and added to the receiving parent’s gross income, before calculating each parent’s net income and percentages.
  • Health insurance premiums for the child will be added onto the child support calculation, and divided between the parents based on their respective percentages of the combined income.
  • Under the new law, the “custodial” parent, or parent with the majority of parenting time, will be entitled to claim the tax dependency exemption for the parties’ minor child, unless the parties otherwise agree, or unless a judge previously ruled otherwise.
  • If a parent is voluntarily unemployed or underemployed, child support will be calculated based on potential income. The court will consider the parent’s work history, available job opportunities, and earning levels in the community.  If there is no work history to determine potential income, there will be a rebuttable presumption that the parent can earn 75% of the U.S. poverty guidelines,  and the court can order a minimum child support amount of $40 per month per child, with a maximum total of $120 per month to be divided among all of that parent’s children.
  • Under the new child support law in 2017, when parents have close to equal amounts of parenting time, the actual number of overnights that each parent has with the children will be taken into consideration when calculating child support.


Why the Changes?

The old “percentage model” has been the method of calculating child support in Illinois for over 30 years.  However, this model usually only considered the paying parent’s income, and did not fully consider both parents’ income.  The new child support law in 2017 attempts to provide for child support similar to what a child would have received if both parents had stayed together.  As of early 2017, Illinois was in the small minority of states which were still using the percentage model of child support calculations.  The new “income shares” model of calculation has become the national trend, and is used in the majority of states.


Can I Change My Child Support Amount Based on the New 2017 Law in Illinois?

Under the new statute, a previous child support order can be modified if there is a substantial change in circumstances.  The 2017 change in Illinois child support law, in and of itself, will not be considered a substantial change in circumstances.  If there was already a child support order entered before July 2017, one cannot file to modify the support amount based solely on the change in law.


(815) 207-9570

Call to schedule an initial consultation

If you or someone you know is seeking professional legal representation in a child support case in Will County, Dupage County, or Kendall County, call (815) 207-9570 to schedule an initial consultation with an experienced family law attorney.



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The information on this site is not legal advice and does not create an attorney-client relationship.  Retain an attorney licensed in the state which has jurisdiction over your matter before taking any action which affects your legal issues, legal marital status or custody arrangements, and follow the advice of your retained lawyer.