How Much Child Support Will I Pay in Illinois?

A change in the law could make a significant difference in support payments

By Doug Mentes, Esq. | Reviewed by Canaan Suitt, J.D. | Last updated on March 28, 2023

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As of July 2017, a new child support law took effect in the State of Illinois. Termed the “income shares” approach, it’s an approach entirely different from the method used in Illinois over the previous 30 years.

The former method was built on the presumption that one spouse worked and earned all the income while the other spouse provided all the childcare and earned little or no income. Because of the changing dynamics of divorced families over the years, Illinois child support law needed to respond to those changes. Many will see the new approach as fairer for the parent who pays support.

As the name suggests, one major difference between the old and new methods is that the income shares approach will consider and combine the income of the parents.

The goal of the law is to calculate the amount of child support based on the amount the child would have been allocated for support had the child remained in an intact household.

The new law eliminates applying percentages to the child support payor’s net income based on the number of children. For example, previously a child support payor would have paid the parent receiving support:

  • 20 percent of payor’s net income for one child
  • 28 percent of payor’s net income for two children
  • 32 percent of payor’s net income for three children

How Is Child Support Calculated?

Child support is computed by applying the ratio of the parents’ adjusted net income to the stated child support obligation for their income level. Specifically, the steps taken to calculate child support now are:

  1. Determine each parent’s net income
  2. Combine both parents’ net incomes
  3. Determine the basic child support obligation for the combined net income amount
  4. Determine each parent’s ratio of individual income to the combined total net income
  5. Multiply the ratio of combined income by the basic support obligation to arrive at each parent’s share of the basic support obligation

By way of example, if the combined monthly net incomes of the parents are approximately $5,450, reviewing the income shares schedule based on net income for one child shows a monthly child support obligation of $1,001. If the paying spouse earns 60 percent of the shared income amount of $5,450, the paying spouse will pay $600 per month in basic Illinois child support.

Child care expenses, health insurance and medical expenses for the child will be added on top of the basic child support amount. The same ratio percentage will apply to those costs as well. Using the previous example where the paying parent pays 60 percent of the basic support amount, that parent will also pay 60 percent of the health care and child care costs of the child.

The Illinois Department of Healthcare and Family Services has developed an online child support calculator to help parents determine what child support will be in their case.

Parenting Time Will Factor Into Calculation

If the paying spouse exercises parenting time of at least 146 overnights per year with the child (40 percent of annual overnights), a different calculation is used to apportion child support.

A parent with at least 146 overnights per year pays the other parent less than they would if they had a lower amount of time. Conceptually, the more time a parent spends with a child, the less money that parent is required to pay to the other, as the child is not living with the child support recipient as much.

Under the statute, a previous child support order can be modified if there is a substantial change in circumstances. However, 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, a parent cannot file to modify the support amount based solely on the change in law.

Getting Legal Help

Besides the change in method to calculate support, other less-significant changes have been made to the law.

Before a parent considers establishing or modifying child support, that parent should consult with a law firm and speak to an experienced Illinois family law attorney about how the new changes in the law will affect their child support payment.

For more information on this area, see our overviews of family law, divorce, and mediation and collaborative law.

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