Changes Coming to Illinois Child Support Calculations in 2027

 Posted on October 08, 2026 in Family Law

For many divorced or unmarried parents, child support plays a major role in a child’s stable upbringing. Whether you are currently paying or receiving child support, you should know about the upcoming changes to support amounts that may affect your family. The most significant changes have to do with how the number of overnights affects the support calculation.

At Goostree Law Group, we have a comprehensive understanding of Illinois’ child support laws. We can address any questions you may have about a current or future court order, drawing on decades of legal experience. Our Kane County, IL family law attorneys are also prepared to represent you in court for issues of enforcement or modification.

What Is the Income Shares Model of Child Support?

The income shares model is the method Illinois uses to set child support. The model rests on the idea that a child should receive the same share of income from both parents that the child would have received if the family still lived together.

Under the income shares model, the court adds both parents' net incomes together. Net income is the money left after taxes and certain other deductions. The court then checks a state chart that shows what parents with that combined income would usually spend on a child. That amount is called the basic child support obligation.

Next, the court splits the obligation between the parents. Each parent is responsible for a share that matches his or her part of the combined income. A parent who earns most of the household income covers most of the cost. The parent who has the child less often usually pays his or her share to the other parent. These rules appear in the Illinois Marriage and Dissolution of Marriage Act.

How Does "Shared Physical Care" Affect Child Support in Illinois?

Shared physical care is the term Illinois uses when both parents spend a large amount of time caring for the child. In these families, each parent pays for food, housing, and other daily costs while the child is in his or her home. The standard formula assumes one parent covers most of those costs. That assumption does not fit when the child splits time more evenly.

To account for this, Illinois uses a different formula once each parent reaches a set number of overnights per year. Under current law, that threshold is 146 overnights, or about 40 percent of the year. When both parents meet it, the court raises the basic obligation to reflect the higher cost of running two homes. It then divides support based on both income and parenting time. Each parent's amount is offset against the other's, and only the difference changes hands. The paying parent usually owes less, though support rarely disappears entirely.

The current system has a sharp cutoff. A parent with 145 overnights gets no shared-care credit, while a parent with 146 gets the full benefit. A single night can change the support amount by a large sum.

How Will the 2027 Changes to Child Support Affect Shared Physical Care? 

The 2027 changes to Illinois child support law take aim at the 146-overnight cliff. The new law lowers the starting point for shared physical care to 110 overnights per year.

Parents with 146 or more overnights will still use the full shared-care formula. Parents with 110 to 145 overnights will fall into a new middle group. For this group, the law uses a table to apply graduated adjustments. A parent near 110 overnights will see a smaller reduction. As overnights climb toward 145, the adjustment increases. Support will change in steps rather than jumping all at once.

Existing orders will not change on their own when the law takes effect. A parent must ask the court to review the order. Parents whose schedules fall between 110 and 145 overnights may want to look at their current support amounts before 2027 begins.

What Counts as an "Overnight" in Shared Physical Care?

An overnight in Illinois child support cases has usually meant a night the child sleeps at a parent's home. That narrow meaning left out many parents who play a large role in their children's daily lives. A parent might pick a child up from school, help with homework, cook dinner, and handle bedtime without the child staying the night.

Under the 2027 changes, Illinois law expands this idea to include "overnight equivalents." A court may count significant blocks of parenting time when the child is in a parent's physical care and under that parent's direct supervision, even without an overnight stay. Long weekday afternoons and evenings could count toward the 110-overnight threshold in the right case.

Overnight equivalents are not automatic. A judge decides whether the time counts, or the parents can agree to it. Calendars, school pickup logs, text messages, and activity schedules can show how much time a parent truly spends with the child.

Does Modifying Parenting Time Affect Child Support in Illinois?

Modifying parenting time in Illinois can affect child support, but changing one order does not automatically change the other. A parent who gains more overnights must still ask the court to recalculate support.

To modify support, a parent generally must show a substantial change in circumstances. A major shift in the parenting schedule can meet that standard. Once the new law takes effect, parents who reach 110 or more overnights may also have a reason to ask the court for another look.

Informal changes can cause trouble. Parents sometimes agree to a new schedule on their own and never update the court order. If a dispute comes up later, the judge will look at the written order, not the private deal. Putting any change in writing and getting court approval protects both parents and the child.

Contact Our St. Charles, IL Child Support Lawyers

The 2027 child support changes could shift what many Kane County families pay or receive. At Goostree Law Group, we review parenting schedules, income records, and current orders to see how the new rules may apply to your family.

We can help you seek a modification, respond to one, or set up a fair order from the start. Contact our Kane County, IL family law attorneys or call 630-584-4800 to set up a free consultation.