How is Illinois Child Support Calculated in 2020?

Illinois Child Support 2020 | Recent Changes to Illinois Child Support Law

Video by Attorney Kevin O'Flaherty
Article written by Illinois & Iowa Attorney Kevin O'Flaherty
Updated on
October 28, 2019

Illinois Child Support 2020 | Recent Changes to Illinois Support Law

In this article, we explain Illinois child support law in 2020, as well as recent changes to Illinois child support law.  We will discuss the following topics:

  • How is Illinois child support calculated in 2020?;
  • How is Illinois child support calculated differently in ‘shared parenting situations’ in 2020?;
  • How to calculate my child support in Illinois;
  • When can Illinois deviate from the child support guidelines in 2020?;
  • When can child support orders be modified in Illinois?;
  • How is child support calculated for careers with varying income over time?;
  • How do maintenance payments affect child support obligations in Illinois in 2020?;
  • How is child support calculated in Illinois for multiple families in 2020?;
  • How is child support determined for college expenses in Illinois?; and
  • How to enforce a child support order in Illinois.

How is Illinois Child Support Calculated in 2020?

There are no major changes to the laws governing child support calculations for 2020.  The most significant change to Illinois Child Support Law occurred in 2017, when Illinois adopted the “income shares” model.  This formula is now used to calculate child support in 40 states.  Under the “income shares” model, economic tables are used to calculate an appropriate amount for child support.  The combined income of the parents, cost of living, and number of children involved are taken into consideration when determining a number for support.

Once an appropriate amount for child support is set by the court, each parent’s portion of the obligation must be designated.  Typically, this is determined by the parents’ relative incomes.  The larger the difference in income between the obligor and obligee, the more the obligor is likely to pay in child support.  The change from a “fixed-rate” model to an “income shares” model affects each case differently.  Spouses with similar incomes will likely receive less in child support under the new law.  The court will also consider if one or both of the parties have an additional child support obligation to children of a different marriage, or whether or not the parents equally share parenting time, when allocating support responsibilities.

How is Illinois Child Support Calculated Differently in “Shared Parenting Situations” in 2020?

The state of Illinois defines a “shared parenting situation” as at least 146 overnight stays with the children per year.  The formula to calculate child support changes slightly in “shared parenting situations,” as the obligation of the payor spouse is increased to 50%.  In a “shared parenting situation,” the amount of time the child spends with each parent is factored into the calculation of each parent’s obligation of support.  The more time the payor parent spends with the kids, the less he or she will pay in support.  However, until the minimum requirement of 146 overnight stays is met, the amount of time spent with each parent is not considered in child support calculation.  For more information, check out our article entitled Illinois Child Support in Shared Parenting Situations | Joint Custody and Child Support.

How to Calculate My Child Support in Illinois

The Illinois Department of Healthcare and Family Services provides several links, forms and tools to help you figure out the amount of child support you will owe or be entitled to.  You will need financial information for both parties to get a precise calculation, but an approximation will help you get an idea of what to expect when the judge makes a ruling.  Some of the information you can get from the IDHFS website includes:

  • A child support “income shares” calculator;
  • An Illinois child support estimator;
  • An overview of the “income shares” model and how it works;
  • A table to assist in converting “gross income” to “net income;”
  • A worksheet to determine child support based on net income; and
  • A worksheet to determine child support if you qualify for a “shared parenting” calculation

For a more in-depth look at the resources from the IDHFS website and how to use them, see our article entitled Illinois Child Support Guidelines | Child Support Calculator Explained.

When Can Illinois Courts Deviate from the Child Support Guidelines in 2020?

The court is required to follow the specific guidelines put forth from the Illinois Department of Healthcare and Family Services unless it is determined that deviating from the statutory guidelines would be in the “best interest of the child.”  State law defines the “best interest of the child” by considering the following factors:

  • The financial needs and resources of the child;
  • The financial needs and resources of the custodial parent;
  • The standard of living the child would have enjoyed had the parents remained together;
  • The physical and emotional condition of the child;
  • The child’s educational needs; and
  • The financial resources and needs of the non-custodial parent

When Can Child Support Orders Be Modified in Illinois?

Child support orders in Illinois can only be modified if one of the following conditions exist:

  • Modification is necessary to provide healthcare for the needs of the child;
  • A “substantial change in circumstances” has occurred since the entry of the order; or
  • The child support order deviates from Illinois guidelines by more than 20%.

If a child support order was entered prior to 2017, the changing of the law is not enough grounds on its own to warrant a modification to the order.  However, if a substantial change in circumstances does occur, the new laws for calculating child support will apply, even if your order was originally entered under the previous law.  To learn more about what qualifies as a “substantial change in circumstances” and how to file a petition for modification of child support, follow the link to our article Illinois Child Support Modification Explained.

How is Child Support Calculated for Careers with Varying Income Over Time?

During the divorce process, each party will be asked to provide a financial affidavit, revealing income from all sources over the course of time, among other things.  The financial affidavit, along with other required information, such as tax returns, bank account information, pay stubs and more, will help to reveal an accurate accounting of income.  The court can also average income over a certain number of months, set a base rate for child support and order the obligor to supplement as they acquire income, and/or order financial information to be exchanged at periodic intervals to square up inaccurate support amounts.  For more detailed information, see our article entitled How Is Child Support Calculated for Overtime, Bonuses, and Varying Income?.

How Do Maintenance Payments Affect Child Support Obligations in Illinois in 2020?

The federal tax reform in 2019 caused some significant changes to be made to Illinois maintenance laws.  Per the changes to Illinois maintenance law in 2019, the combination of maintenance and child support payments cannot exceed 50% of the payee’s net income.  For more information about spousal maintenance and the impact it has on child support, see our article entitled How Do Spousal Maintenance Payments Impact Child Support Obligations in Illinois?.

For a larger overview of spousal maintenance, see our article Illinois Spousal Maintenance 2020 | Changes to Illinois Spousal Maintenance Law for 2020..

How is Child Support Calculated in Illinois for Multiple Families in 2020?

If the obligor spouse has more than one obligation of child support, the order in which those obligations began is very important.  Earlier support orders will receive larger payments than the later orders, as the obligor spouse’s net income will decrease as funds are chronologically taken from the obligor.

For example, if Person A has a net income of $100,000 and is ordered to give 20% of his net income to Person B for child support, then Person B will receive $20,000 that year.  Next year, Person A is ordered to give 20% of his net income to Person C for child support, making this his second obligation of child support.  Person A still has a net income of $100,000.  In this case, Person B will receive $20,000 for child support, and Person C will receive $16,000 for child support.  The money that goes to Person B for support is not included in Person A’s net income; therefore the net income of Person A is $80,000 when providing support to Person C, making 20% of that net income $16,000.  You can find more information in our article, How is Child Support Calculated for Multiple Families in Illinois?.

How is Child Support Determined for College Expenses in Illinois?

Typically, child support is owed until the child turns 18 or graduates high school.  The state of Illinois does not require child support for college expenses.  If there is going to be an obligation for either or both parents to help pay for college, the person seeking support must prove that support is appropriate.  From there, the court will either deny the request or award support to the seeking party, along with a designated dollar amount and duration for further support.  See our article entitled Illinois Child Support and College Expenses for more information.

How to Enforce a Child Support Order in Illinois

The Illinois Department of Child Support Services can help to enforce a child support order, as well as a contempt proceeding in court, or both. For more detailed information, see our article about How to Enforce Child Support in Illinois.


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