When Does Child Support End in Illinois?

The general rule: 18, or 19 while still in high school

Two sections of the Illinois Marriage and Dissolution of Marriage Act set the end date. Section 505(a) defines a "child" for support purposes as anyone under 18, plus an 18-year-old who is still attending high school and has not turned 19. Section 505(g) says every support order must include a termination date. That date can be no earlier than the child's 18th birthday. If the child will graduate from high school after turning 18, the date can be no earlier than graduation or the 19th birthday, whichever comes first.

Section 510(d) states the rule from the other direction. Unless the Act provides otherwise, or the parents agreed in writing, or the judgment says otherwise, support ends when the child is emancipated, or, for an 18-year-old still in high school, on graduation or at 19, whichever is earlier. Section 510(d) also says a paying parent's death does not end the obligation. The support may be enforced, modified, revoked or converted to a lump sum, as fairness requires.

The same rules apply to orders entered in parentage cases. Section 801(d) of the Illinois Parentage Act of 2015 repeats the termination date requirement.

Sections you are most likely to see

Emancipation and other early end dates

Section 505(g) says nothing in the termination date rule stops the court from modifying or ending an order if the child is "otherwise emancipated." These sections do not list what counts as emancipation, so a parent who believes a child is emancipated before 18 should ask the court for an order rather than decide alone.

A written agreement or the judgment itself can also change the default rule. Section 510(d) begins with "unless otherwise provided," so read your marital settlement agreement and judgment closely. Some orders set a different end date or a step-down for each child.

When there is more than one child, check whether the order lists separate amounts or end dates. If it sets one combined amount, the order may not adjust on its own when the oldest child ages out, and a parent may need to file a motion to modify support for the younger children under section 510. Our guide on how to modify child support in Illinois covers that motion.

The 2027 shared-care change does not move the end date

Public Act 104-0733 takes effect January 1, 2027. It lowers the shared physical care threshold in section 505(a)(3.8) from 146 overnights a year with each parent to 110 overnights, or overnight equivalents found by a court or agreed by the parents. Through December 31, 2026, the 146-overnight rule applies. The new law changes how support is calculated, not when it ends.

After January 1, 2027, section 510 also says that the passage of a new Public Act is not, by itself, a substantial change in circumstances unless that Act expressly says so. Read our post on the 2026 and 2027 Illinois child support rules for details.

College expenses are a separate claim

Section 513 lets the court order either or both parents to contribute to a child's college, vocational or other post-high school education, and to high school costs for a student who is still in high school after 19. This is not child support, and it has its own rules:

• Unless the parents agree otherwise, expenses must be incurred by the student's 23rd birthday, or by the 25th birthday for good cause.
• Covered expenses can include tuition and fees, housing, medical and dental costs, reasonable living expenses, and books and supplies. Unless there is good cause, tuition and fees are capped at in-state tuition and fees at the University of Illinois at Urbana-Champaign, and housing is capped at the cost of a double room with a standard meal plan in a residence hall there.
• The court can require the parents and child to complete the FAFSA and can order payment for up to 5 college applications, 2 entrance exams and one exam prep course.
• The court's authority ends if the student fails to keep a cumulative "C" average (except for illness or other good cause), turns 23, earns a bachelor's degree or marries.
• Under section 513(k), a new obligation is retroactive only to the date a petition is filed.

That last rule matters. Waiting until after tuition is paid can limit what the court can order. See our post on college expenses for divorced parents in Illinois.

Support for a non-minor child with a disability

Section 513.5 lets the court order support for an adult child who is mentally or physically disabled and not otherwise emancipated. The request can be made before or after the child turns 18. Unless the request is paired with a section 513 education claim, the disability must have arisen while the child was still eligible for support under section 505 or 513.

The statute defines a disability as a physical or mental impairment that substantially limits a major life activity. The court weighs both parents' resources, including retirement savings, the standard of living the child would have had, the child's own resources, and benefits such as Supplemental Security Income. Payments may go to a parent, to a trust the parents create for the child, or to a trust for a beneficiary with a disability that meets the federal and state rules the statute lists. Ask how an award may interact with any benefits the child receives.

Arrears do not end when support ends

Unpaid support survives the end date. Section 505(g) requires every order to state that the termination date does not apply to arrears. Under section 505(g-5), if at least one month's support is unpaid when current support ends, the same periodic payment continues, now applied to the arrears, and it can be collected by income withholding.

Section 505(d) treats each missed installment as a judgment with the full force of any Illinois judgment, and a lien arises against the paying parent's property. Section 505(i) says the court keeps its contempt and other enforcement powers after the child is emancipated. Our guide to enforcing a child support order explains the options.

Steps in Cook County

1. Find the termination date in your support order or judgment. Check for agreed terms about college or later support.
2. If the date is missing, unclear or disputed, or a child is emancipated early, file a motion in the court where the order was entered or last modified, as section 511 provides. For a Cook County order, that is usually the Domestic Relations Division of the Circuit Court of Cook County.
3. Give the other parent notice. Under section 510(a), changes apply only to payments that come due after notice of the motion.
4. If support is paid by income withholding, ask for an order the employer and the State Disbursement Unit can follow.
5. File any college expense or disability support petition before the costs are incurred.

Bring the order, the payment history, the child's expected graduation date, school records, and any college cost or disability documentation.

Common mistakes

• Stopping payments early without checking the order.
• Assuming support ends when the paying parent dies.
• Waiting to file a college expense petition until after the bills are paid.
• Assuming the 2027 law changes an existing order automatically.
• Ignoring arrears because current support has ended.

The other parent can argue the child is still in high school, rely on a written agreement extending support, oppose a college request on the section 513(j) factors, or seek enforcement of arrears.

How Chicago Family Attorneys can help

• Read your order and judgment and explain when support ends.
• Prepare motions to terminate, modify or clarify support.
• File or respond to college expense and adult disabled child support petitions.
• Seek or defend against enforcement of arrears in Cook, DuPage, Will and Lake Counties.
• Offer limited scope help: document drafting from $500 or one hearing appearance from $1,200.

Full representation starts with an initial payment of $1,500 to $2,500, then $500 to $650 per month beginning 30 days after the initial payment while representation remains active. See the child support cost page, our Chicago child support services page and whether you need a lawyer for child support.

This article is general information about Illinois law, not legal advice for your situation, and it does not predict the outcome of any case.