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Calculating Child Support in Illinois

NOTE: A new Illinois law governing how child support is calculated went into effect in July 2017. Please visit our child support page for details

child support, Illinois child support law, child support lawyer, Illinois family lawyer, DuPage County family lawWhen parties going through a divorce have children, the issue of child support will inevitably arise. How child support is calculated is different in each state; some have complicated formulas which are difficult for parties to understand. The Illinois child support statutes are relatively straightforward, from a legal perspective. While there are some gray areas which allow room for argument regarding support, a skilled family law attorney can make the process of calculating child support relatively easy.

Illinois statute 750 ILCS 5/505 defines a child, with respect to child support, as one “under 18 or any child under 19 still in High School.” The statute further states that parents have a duty of support owed to a child which includes an obligation to provide for “reasonable and necessary educational, physical, mental, and emotional health needs of the child.” Although both parents technically owe a duty of support, the non-custodial parent (or non-residential parent) often ends up as the payor of support to the custodial/residential parent (the parent with whom a child or children primarily resides).

Calculating Support

Rather than create a long and complex formula as other states have done, Illinois takes a percentage share of the supporting parent's income. The percentage paid correlates to the amount of children resulting from the marriage as follows:

  • For one child, 20 percent of the supporting parent's net income must be paid;
  • For two children, 28 percent must be paid;
  • For three children, 32 percent must be paid;
  • For four children, 40 percent must be paid;
  • For five children, 45 percent must be paid; and
  • For six or more children, 50 percent must be paid.

These guidelines are used almost exclusively by the Courts; however, there is room for the court to deviate from these guidelines under certain circumstances. Some factors the court may consider in deviating from the percentage guidelines are the income and resources of each parent and of the child as well. In the event that deviations from the guidelines are necessary, the court (or the agreement of the parties) must state the support that would be due under the guidelines as well as the reasons for the deviation.

Additional Support Guidelines

In addition to the percentage of net income the supporting parent is required to pay, a court may also require parents to contribute and support the child in other expenses if such expenditures are found to be reasonable by the Court. Such additional expenses include:

  • Health care not covered by insurance;
  • Child/day-care;
  • Educational expenses; and
  • Extracurricular activities.

What is Net Income?

Under the statute, net income is defined as the total income from all sources minus:

  • Federal Income Tax;
  • State Income Tax;
  • FICA/Social Security Tax;
  • Mandatory retirement contribution required by law or as a condition of employment;
  • Union dues;
  • Health and hospital insurance premiums for dependents or individuals;
  • Premiums for life insurance ordered by the Court to reasonably secure payment of ordered child support;
  • Previous obligations of maintenance or support actually paid due to Court order;
  • Expenditures to help pay debts that represent reasonable and necessary expenses for the production of income, certain medical expenses, and certain expenditures for the child or other parent, which does not include gifts; and
  • Health insurance, where the supporting parent is required to pay under an employee benefits plan.

There is significant room for argument over what constitutes “income” as well as whether and to what extent any of the above deductions apply. Parents often think their net take-home pay is what support will be based on; while this is a rough approximation, it is not the same as the statutory calculation of net income. Additionally, expenditures for certain debts for the production of income, certain medical expenses, and other deductions under the statute are not necessarily easily calculated. In these circumstances, the assistance of an experienced family law attorney can prove invaluable.


Failure to pay child support as ordered can result in a court finding of contempt. If a parent is found guilty of contempt, that parent can be forced to pay back-owed support, with interest, as well as the attorney's fees of the parent who had to seek enforcement of the support order. In more serious cases, the court can order incarceration.

When to Call an Attorney

Inevitably, the issue of child support will come up in the larger divorce picture. A talented and dedicated family law attorney can help parents determine the appropriate amount of child support as part of an overall divorce settlement or as an individual issue. If you have any questions regarding child support and need assistance with this or any other divorce related issues, call the dedicated attorneys at Mirabella, Kincaid, Frederick & Mirabella, LLC today for a free consultation.

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From our law office in Wheaton, IL the family law and civil litigation law attorneys of Mirabella, Kincaid, Frederick and Mirabella, represent businesses and individual clients throughout the western suburbs of Chicago, Illinois including Wheaton, Naperville, Oak Brook, Glen Ellyn, Carol Stream, Lombard, Downers Grove, Burr Ridge, Lisle, Elmhurst, Oakbrook Terrace, Winfield, Woodridge, Warrenville and throughout DuPage, Kane and Kendall Counties.

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In honor of the passing of our founder, Joseph F. Mirabella, Jr., our offices are closed Friday, January 31, 2020.I Agree