Illinois Just Rewrote the Child Support Math
Updated: 2 hours ago
For years, Illinois child support has had a hard cliff built into it: the shared-parenting formula only kicked in at 146 overnights a year. One overnight on the wrong side of that line and a parent could be treated as if they had no significant parenting time at all. It led to a lot of fights over a single night that had nothing to do with what was actually best for the kids.
That cliff is gone.
On July 31, 2026, Governor Pritzker signed SB 3524 (Public Act 104-0733), which changes how Illinois calculates child support when parents share parenting time. It takes effect January 1, 2027.
What's changing
The threshold for shared-parenting calculations drops from 146 overnights to 110. And instead of an all-or-nothing cutoff, parents in the 110–145 range get a graduated adjustment based on exactly how many overnights they have:
110–114 overnights: +10%
115–119 overnights: +9%
120–124 overnights: +8%
125–129 overnights: +7%
130–134 overnights: +6%
135–139 overnights: +4%
140–145 overnights: +2%
At 146 or more, the full shared-care formula still applies: the basic support obligation is multiplied by 1.5, then split between the parents based on their share of combined income.
Want to see what the formula produces for your numbers? The calculator below runs today’s rules, so if your overnights land between 110 and 145 it will tell you that the 2027 adjustments are coming, but it will not apply them yet.
Daytime parenting finally counts.
The new law also lets courts count substantial daytime care as “overnight equivalents.” A parent who handles school pickups, dinners, and bedtime routines — but not the overnight itself — can now have that time reflected in the support calculation.
A few other changes worth knowing about
The bill touches some other pieces of the support statute, too:
The low-income cutoff expands. The income threshold for the minimum child support presumption rises from 75% to 100% of the federal poverty guidelines for a one-person family, so more low-income parents will fall under the minimum-support rules. The presumption remains rebuttable, and the minimum obligation itself stays at $40 a month per child, capped at $120 total.
Incarcerated parents get a new presumption. A parent incarcerated for more than 180 consecutive days is now presumed unable to pay child support. Like the low-income presumption, it can be rebutted with evidence — for example, that the parent has assets or income available during incarceration.
Annual income disclosure becomes mandatory. Child support orders must now require parents to exchange written documentation verifying their net income every year, and to report a new job or job loss within 10 days. That's a meaningful shift: instead of finding out about a raise years later through discovery, both parents will see the numbers annually.
What this means for you and your child support
If you pay or receive child support and you share parenting time, the math may look different starting in 2027 — especially if your overnights fall anywhere near the old 146-night line or the new 110-night line.
Nothing changes automatically. Existing orders stay exactly as written until someone goes back to court and asks for a modification. If your schedule is close to one of these thresholds, or your current order was shaped around hitting or avoiding the old 146-night cutoff, it's worth talking through whether a modification makes sense once the law takes effect.
And if you're not sure how many overnights you actually have, this is a good reason to count. Your parenting plan says one thing; what actually happens during the school year is sometimes another. Under the new graduated table, the difference between 114 and 115 overnights changes the number.
LaRocque Law | (331) 306-0084 | larocque-law.com | Schedule Online
Nothing here is legal advice, and your situation is not the one I'm describing. If it sounds close, schedule a consultation and we'll talk about yours specifically.
