Illinois Child Support Changes Are Coming in 2027: Here's What Parents Need to Know

The Illinois legislature is once again adjusting how child support is calculated in the state. Beginning on January 1, 2027, Senate Bill 3524 will modify how Illinois courts apply the Income Shares model to calculate child support, particularly in cases involving co-parents who both exercise significant parenting time. S.B. 3524, 104th Gen. Assemb., Reg. Sess. (Ill. 2026); 750 ILCS 5/505; 750 ILCS 5/510.

For many families, these changes are not just theoretical. They will directly affect how much financial support they pay or receive, how parenting time is counted, and how courts recognize the evolving realities of modern parenting arrangements.

Changes to Shared Parenting Time: Not Just 146 Overnights Anymore

Conceptually, shared parenting time is the idea that when both parents have their kids at their homes a significant portion of time, they typically spend more money to maintain the basic framework of the kids' daily lives. For example, both parents may need to have things for the kids at both homes, such as sports equipment, computers, musical instruments, etc. Parents with shared parenting time also spend more on essentials like clothing, food, and medical supplies. Because that financial burden is spread more evenly between homes and does not fall disproportionately on one parent, the Illinois legislature reasons that child support can be decreased, and they adjust the support calculations accordingly.

Under the current laws, parents who spend 146 overnights per year or more with their kids fall within the "shared parenting" model for the purposes of calculating child support. 750 ILCS 5/505(a)(3.8). That threshold gives those parents a clear and financially meaningful distinction: if they hit the 146-overnight mark, the child support they pay or receive significantly decreases.

Starting in 2027, however, all that changes.

The new law lowers the shared parenting threshold to 110 overnights. S.B. 3524, 104th Gen. Assemb., Reg. Sess. (Ill. 2026) (amending 750 ILCS 5/505(a)(3.8)(3)). It also provides a new method for calculating shared support when a parent has between 110 and 146 overnights. S.B. 3524, 104th Gen. Assemb., Reg. Sess. (Ill. 2026) (amending 750 ILCS 5/505(a)(3.8)(1)). This means that many more parents will now qualify for the shared parenting formula and the resulting decrease in child support.

What This Means for You

• The financial advantage historically tied to crossing 146 overnights will be diluted.
• Courts will apply shared parenting calculations in a wider range of cases, potentially reducing support obligations even when parenting time is uneven.
• You may see less dramatic differences in child support between a 50/50 schedule and a 60/40 schedule.

It will matter less now whether a parent has 146 overnights or more, as the legal significance of that specific number is decreasing. Strategy will shift from "crossing a threshold" to demonstrating a parent's actual day-to-day caretaking responsibilities.

For parents with fewer than 146 overnights, this change in legislation will have a significant impact. By lowering the threshold to 110 overnights, Illinois is recognizing that parenting is more than where a child sleeps.

The new law also contains a new adjustment framework for parents who exercise between 110 and 145 overnights, addressing the gray area that previously led to inequitable results. S.B. 3524, 104th Gen. Assemb., Reg. Sess. (Ill. 2026) (amending 750 ILCS 5/505(a)(3.8)(3)). This means there is now a precise way of calculating child support for a parent who has 112 overnights, 121 overnights, or 132 overnights. This greater precision will hopefully result in more equitable support awards that reflect a parent's involvement in their children's lives.

What This Means for You

• You may qualify for shared parenting support calculations even if you have fewer than 146 overnights.
• You may be obligated to pay or receive less child support than you would have previously.

Overnight Equivalents

Historically, many parents were heavily involved in their kids' daily lives, caring for them on multiple weeknights, taking them to activities, providing transportation, and helping with homework, but still fell short of the 146-overnight threshold. As a result, they were treated as if they had little meaningful parenting time for the purpose of calculating child support, and their resulting support obligations were higher. The new law corrects that gap by taking into consideration time spent parenting during the day.

So what exactly will the courts consider an "overnight equivalent"? The new statute explains:

"Overnight equivalents are calculated by using a method other than overnights if the parent has significant parenting time periods on separate days in which the child is in the parent's physical care and under the direct care of that parent but does not stay overnight." S.B. 3524, 104th Gen. Assemb., Reg. Sess. (Ill. 2026) (amending 750 ILCS 5/505(a)(3.8)(1)).

It will take some time to determine how the courts interpret this new concept, but the door is now open to look beyond the old overnight paradigm.

If you are actively parenting but historically felt "invisible" in the math, this change is designed for you. However, documentation of your involvement in such things as school pickups, medical appointments, and extracurriculars will become even more important.

A Step Toward Fairer Treatment for LGBTQ Parents in Non-Traditional Families

For LGBTQ families, these updates to the Illinois child support laws are particularly meaningful. Many LGBTQ parenting arrangements do not fit neatly into traditional frameworks. There may be:

• Non-biological or non-adoptive parents with substantial caregiving roles
• Flexible or non-traditional parenting schedules
• Intentional co-parenting structures formed outside marriage

Because Illinois child support laws historically relied heavily on overnight counts and rigid categories, non-traditional families were often disadvantaged. Under the new law, however, that should change:

• Lowering the shared parenting threshold makes it easier for both parents to be recognized as active caregivers.
• Expanding shared-care eligibility aligns better with fluid, modern parenting arrangements.
• The shift away from rigid overnight benchmarks helps courts consider the substance of parenting time over the form.

Important Limitations to the New Child Support Laws

While these changes coming to the Illinois child support laws in 2027 improve how child support is calculated, they do not automatically resolve legal parentage issues. LGBTQ parents must still ensure their parental rights are legally established.

If you are an LGBTQ parent, this change in the law is a positive step toward fairness in financial allocations of support. But your protection as a parent still requires clear legal parentage and allocation judgments.

The Bigger Picture: Illinois Is Catching Up to Reality

Illinois is not abandoning the Income Shares model of calculating child support; it is merely refining how it applies. What we are seeing is a shift away from rigid thresholds and toward a more nuanced, fact-sensitive analysis of parenting time that is long overdue.

As with any change in the law, implementation is about to get complicated. For the foreseeable future, as the courts grapple with how to interpret the changes through real-life cases, legal outcomes may become less predictable. Small differences in parenting schedules may carry big financial consequences for your family. One thing is certain: strategic legal planning with a skilled family law attorney throughout your case will make a big difference to your bottom line.

Reach Out to a Chicago Family Law Attorney for Help

These changes in the Illinois child support laws are not one-size-fits-all. They will benefit some parents, disadvantage others, and create new questions for many.

If you are a parent just below the old 146-overnight threshold, a parent currently receiving or paying support under a shared schedule, or part of an LGBTQ family navigating the legal process, now is the time to revisit your arrangement. Talk to a family law attorney who knows the new law before you make any decisions.