Child Support in Illinois

Find out how child support is calculated in Illinois, whether parents can agree to support that doesn't follow the guidelines, and how to change the amount of support or get help collecting support.

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All parents have a legal obligation to support their children. When the parents are living together, they provide that support directly. But when the parents are separated, divorced, or never married, state courts may order them to pay child support.

Like all states in the U.S., Illinois has child support guidelines for calculating how much parents must pay. Parents can agree on an amount of child support, but those agreements will almost always need to meet the guidelines. That's because the right to receive support belongs to the child—not the parents.

How Is Child Support Calculated in Illinois?

Before 2017, Illinois courts used a "percentage based" formula for child support. So you would see tables showing support amounts as a straight percentage of the paying parent's income, depending on the number of children. That's not how it works now. The Illinois child support guidelines use what's known as the "income shares" model, which considers both parents' incomes when calculating the amount of support.

Basic Steps to Compute Illinois Child Support Amounts

You may use the Illinois Child Support Estimator to calculate an estimated amount of support that would apply in your case. However, as the name indicates, this is not an actual "calculator." Instead, it's meant to give you a general idea of the support amount based on the numbers you enter.

For a more precise calculation of child support, you can use the worksheet and tables provided on the Illinois Child Support Guidelines-Income Shares webpage. Or, if you qualify to file for divorce online, some of the reputable services will do the calculations for you, based on your answers to a questionnaire.

Here are the basic steps to calculate child support in Illinois:

  • Calculate each parent's net income. After calculating gross income from all sources, you'll either use the conversion table for standardized net income (which is updated annually, based on standard tax deductions) or calculate individualized net income based on your deductions (but this will require an agreement with the other parent or a court order).
  • Adjustments to the parents' net incomes. The formula allows for an adjustment when one or both parents are also supporting children from other relationships. There might also be an adjustment for spousal maintenance (alimony) payments.
  • Child support obligation. Based on the parents' combined adjusted net income, the Income Shares Schedule shows the total basic amount of child support. Each parent's contribution toward that total amount is then based on their share (as a percentage) of the combined net income.

(750 Ill. Comp. Stat. § 5/505 (2023).)

Additions to Basic Child Support in Illinois

The judge may also require—or the parents may agree to—additions to child support for the cost of things like:

  • health insurance coverage
  • unreimbursed health care expenses
  • child care
  • extraordinary medical or educational expenses
  • extraordinary extracurricular activities, and
  • life insurance to ensure that there will be money for the child if one of the parents dies.

(750 Ill. Comp. Stat. § 5/505 (2023).)

Which Parent Pays Child Support?

The calculation of child support under the Illinois guidelines results in an amount that each parent is obligated to provide for the child or children. The state assumes that the parent with primary physical custody of the children (the "custodial parent") will spend that amount of money directly on the child. The other parent (the "noncustodial parent") will pay support to the custodial parent. (750 Ill. Comp. Stat. § 5/505 (2023).)

How Does Shared Custody Affect the Calculation of Child Support in Illinois?

The Illinois child support guidelines account for the fact that shared physical custody—when each parent has the kids for a significant amount of time—can result in increased costs. Among other things, both parents need to provide bedrooms (or at least sleeping areas) and other basics for the children.

Illinois provides a separate worksheet for calculating child support when each parent has the child for at least 146 nights during the year. In these situations, the total basic support obligation is multiplied by 1.5 (or 150%). Each parent's share of the total obligation is based on their percentage of the combined incomes, as well as the percentage of time the child spends with the other parent.

Illinois also provides a way of calculating support when the parents split physical custody of more than one child. (750 Ill. Comp. Stat. §5/505 (2023).)

How Does the Number of Children Affect the Amount of Child Support?

Under the Illinois child support guidelines, the basic support obligation for one child isn't simply multiplied by the number of children. Instead, the schedule shows a step-by-step increase for each additional child.

When Child Support May Be Different Than the Guideline Amount

A judge may order an amount of child support that's different that what it would be under the Illinois child support guidelines, but only if the judge explains why applying the guidelines would be unfair or inappropriate. The judge must consider the child's best interests and the circumstances, including:

  • the standard of living that the child would have had if the parents had stayed married
  • the child's special needs, and
  • the parents' financial resources and needs, including extraordinary medical expenses.

These requirements also apply when the parents agree to an amount of support that departs from the guidelines. The judge may approve their agreement only if they've provided adequate, acceptable reasons why the guideline amount would be inappropriate. (750 Ill. Comp. Stat. § 5/505(a)(2) (2023.)

Imputing Income for Child Support

Even if you have no income, you could potentially end up owing child support.

When judges believe that parents are voluntarily unemployed or underemployed (working at lower-paying jobs than they're qualified for, or working fewer hours than they could), the judges will look carefully at the reasons for the reduced income. Parents need to have a good reason why they aren't earning as much as the judge believes they could, such as a medical condition, disability. And if they simply haven't been able to find a better-paying job, they'll need to provide evidence that they've been seriously trying. Otherwise, the judge may calculate child support based on "imputed" (potential) income.

Imputed income may be based on:

  • the parent's employment history, including earnings in previous jobs
  • local job opportunities for someone with that parent's qualifications, training and experience
  • prevailing wages in the local community, and
  • any substantial assets that the parent owns.

If an unemployed parent doesn't have enough of a work history to determine the potential for employment and earnings, the judge will usually impute income at 75% of the current federal poverty guidelines for a single-person household. The maximum child support obligation for that parent would be a total of $120 a month, to be divided equally among the parent's children. (750 Ill. Comp. Stat. §5/505 (2023).)

Modification of Child Support in Illinois

Either parent may ask the court to change the amount of child support—or end support payments entirely. Usually, however, a judge will only modify support if there's evidence of a "substantial" change in circumstances. Typically, that means a significant change in the child's needs, a parent's ability to pay, or both.

There are two exceptions to the changed-circumstances requirement for a support modification:

  • If a parent is receiving enforcement help from the Illinois Department of Healthcare and Family Services (more on that below), the judge may change the amount of support if there's a discrepancy of at least 20% (but no less than $10 a month) between the existing support amount and a new calculation under the child support guidelines. However, this exception won't apply if the existing amount was a deviation from the guidelines, and there hasn't been a substantial change in circumstances since then.
  • The judge might also increase support when there's evidence that it's necessary to provide for the child's health care needs.

Can a Parent's Remarriage Affect Child Support in Illinois?

As mentioned above, the child support guidelines in Illinois allow an adjustment when parents are also supporting children from other relationships. So if you or your ex have kids with a new spouse, that might justify a change in the amount of child support.

But what if the remarriage has significantly improved your ex's financial picture regardless of any additional children? Can you get a modification in your current child support order? Unfortunately, there isn't a clear answer in Illinois. Traditionally, the state's courts didn't consider the income of a parent's new spouse when calculating child support for the purpose of a modification request. That approach was based on the principle that stepparents have no legal obligation to support their stepchildren.

However, at least some appellate courts in Illinois have started to take a different approach. Under this new approach, courts have held that judges may consider all of the parents' financial resources that are available to pay support for the child. Those resources could include a new spouse's income or other assets that contribute to the parent's living expenses and thus free up money for paying child support or postsecondary educational expenses (more on that below). (Street v. Street, 756 N.E.2d 887 (Ill. Ct. App. 2001).)

Most of the courts that have weighed in on this issue have emphasized that judges shouldn't use a new spouse's income as the baseline for the parent's contribution to child support or college expenses, nor should they impute income to a parent based on the new spouse's income. (For example, see In re M.M., 29 N.E.3d 1197 (Ill. Ct. App. 2015).) However, at least one appellate court panel held that a judge had correctly used the combined income of the father and his new wife when calculating the modified amount of child support he owed. Still, the dissenting justice strongly disagreed with that approach. (In re Marriage of Rushing, 127 N.E.3d 769 (Ill. Ct. App. 2018).)

For now, at least, courts in Illinois might rule on this issue in different ways. So you should speak with an experienced Illinois family law attorney if you and your ex are fighting about a child support modification and the impact of a new spouse's income.

When Does Child Support End in Illinois?

Generally, child support in Illinois ends:

  • when the child turns 18 or is emancipated before then, or
  • if the child is still in high school, when the child graduates or turns 19 (whichever happens first).

However, the parents may agree—or the judge may order—that either of both parents will pay a child's educational expenses up to age 23 (or to age 25 if there's a good reason for extending payments the extra two years). These expenses include:

  • tuition and fees for college or other postsecondary education
  • the child's housing, medical and other living expenses while attending school, and
  • some costs related to college applications.

When judges are deciding whether to order a parent to pay these educational expenses, they must consider all reasonable and relevant factors, including:

  • both parents' current and future financial resources (including retirement savings) to meet their needs
  • the standard of living the child would have enjoyed if the parents' marriage had lasted, and
  • the child's financial resources and academic performance.

(750 Ill. Comp. Stat. § 5/513 (2023).)

Illinois judges may also order support for adult children who are mentally or physically disabled and aren't able to support themselves. (750 Ill. Comp. Stat. § 5/513.5 (2023).)

In both of these situations (postsecondary education and disability), judges may order that the support be paid from either or both parents' income, property, or estate.

How to Get Help With Child Support

The Illinois Department of Healthcare and Family Services (DHFS) is a state agency that provides a range of child support services for parents, including help with:

  • establishing parenthood for a child
  • getting a child support order
  • collecting current and overdue support payments, and
  • requesting a child support modification.

You can apply for services on the DHFS website. If you have questions, you can call at at 1-800-447-4278 (Monday–Friday, 8:00 a.m.–4:30 p.m.).

If you and your spouse are preparing for divorce and trying to work out a settlement agreement, you might be wondering how your custody arrangements will affect child support, and vice versa. Child support and custody may also be related to other decisions, such as whether one parent will stay in the family home with the kids—and, if so, how you'll deal with the mortgage payments and other house-related expenses. Speaking with a family lawyer could save you surprises and headaches down the road. Divorce mediation can also help you resolve these interconnected issues in a way that works out for both parents and the kids.

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