Calculate Child Support Payments in Illinois

Learn how to calculate child support in Illinois, when the amount of support may be different than what’s calculated under the state’s guidelines, and how to apply for, collect, and modify child support.

By , Legal Editor

How to Use the Illinois Child Support Calculator

To calculate the amount of child support that may apply in your case, you can use the state's online Child Support Estimator. You'll need to have some basic information on hand before doing the calculations, including both parents' income, what your physical custody (parenting time) arrangements will be, any spousal maintenance (alimony) that either parent is or will be paying, and certain expenses for your children (including for health insurance coverage and child care).

If you're still negotiating issues like custody and spousal maintenance, you might try multiple calculations under different scenarios.

Learn more about how child support works in Illinois, including how to calculate net income, allowed additions to basic support, and how shared custody affects the amount of child support.

Are Other Child Support Calculators Accurate?

Watch out for other (nongovernmental) websites with so-called child support calculators for Illinois. Unfortunately, there's no guarantee that these calculators are accurate and up-to-date. Illinois updates its child support guidelines regularly, and you usually can't tell whether any of these other websites have kept up with the latest changes.

It's best to stick with the official state calculator to get the most accurate estimate of the amount of child support you might pay or receive. But notice that word "estimate." The judge may order a different amount in your case (more on that below). Of course, the accuracy of the estimate will also depend on the accuracy of the information you provide.

When Child Support May Be Different Than the Guideline Calculation

The amount of child support calculated under the Illinois guidelines won't necessarily apply in every situation. The state presumes that's the right amount. But you may argue that a different amount would be better in your situation.

Whether you and the child's other parent have agreed on a support amount that departs from the guideline or a judge makes that decision for you, the judge will have to find that the guideline amount would be unjust or inappropriate. When making that finding, the judge will consider the child's best interests under the circumstances, including:

  • both the child's and the parents' financial resources and needs
  • the child's emotional and physical condition, including any educational and other special needs, and
  • the standard of living the child would have enjoyed if the parents had stayed together.

(750 Ill. Comp. Stat. § 5/505(a)(2) (2024).)

How to Apply for Child Support in Illinois

Most parents apply for child support as part of the process of filing for divorce in Illinois. But there are other situations when you might need to request child support—most obviously, when you were never married to the child's other parent. In that case, the Division of Child Support Services (DCSS) in the Illinois Department of Healthcare and Family Services can help you get a child support order. You can enroll for services with DCSS online. As part of its services, the DCSS can help with establishing the child's legal paternity (or parentage) and locating a missing parent, if that's necessary.

How to Collect Child Support in Illinois

If you're having trouble collecting support payments, the DCSS can also help enforce court-ordered child support in Illinois. Depending on how much the other parent owes, the agency has several enforcement tools, including:

  • withholding support from paychecks
  • reporting the debt to credit bureaus
  • intercepting income tax refunds or unemployment benefits
  • seizing money from bank accounts, placing liens on property (so the delinquent parent can't sell it or borrow money before paying off the debt), and
  • suspending the parent's driver's or other licenses.

How to Change the Amount of Child Support

Either parent may request a modification of child support in Illinois. However, the judge won't change the existing support order unless you can show one of the following:

  • there's been a substantial change in circumstances—such as a parent's reduced or increased income—since the existing support order was issued
  • there's a difference of at least 20% (but no less than $10 per month) between the existing order and the amount that would be calculated now under the Illinois child support guidelines (unless the existing order was based on an allowable deviation from the guidelines), or
  • the change is needed to provide for the child's health care needs.

(750 Ill. Comp. Stat. § 5/510(a) (2024).)

You may ask the Illinois DCSS to review your existing child support order to see if it warrants a modification. Because the review process can take a while, you may instead choose to file a modification request directly with the court. In that case, however, you should consider speaking with a family law attorney to get help with the legal process.

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