Starting Jan. 1, 2027, Illinois parents who each have a child for at least 110 overnights a year will be treated under the state’s shared-care child support formula. The old cutoff was 146 overnights, so a lot of parenting schedules that used to be calculated the standard way will now be run through a different set of numbers.
The change comes from Senate Bill 3524, which the legislature passed this spring and which was signed into law in the summer. It leaves current orders alone, but it will matter to any family that heads into court or mediation after the new year.
What the 110-Overnight Threshold Changes
Under the current rules, the shared physical care formula only applies when each parent has the child for 146 or more overnights a year, which is a bit more than 40 percent of the calendar. According to Family Law Software’s summary of the law, the threshold drops to 110 overnights per year, and the multiplier of 1.5 used in shared-care math is kept. Parents whose schedules sit between an even split and a standard every-other-weekend arrangement are the ones likely to notice the shift. Money questions like these tend to sit beside others in the household budget, such as the Child Tax Credit’s $2,200 per child, and a roundup of gentle parenting basics covers the day-to-day side of sharing time.
Senator Michael Hastings, who backed the bill, said in a press release on the signing that parents who are actively involved in raising their children should have that involvement fairly recognized. The law also lets courts, in suitable cases, count “overnight equivalents,” meaning substantial daytime care that does not involve a sleepover. The text does not set a formula for that, so judges and parents have room to decide how it works. Hastings framed the change as families evolving faster than old rules, much like the debate over social norms that may be due for a rethink. Anyone raising children while also caring for older relatives may recognize the strain, as laid out in a look at the sandwich generation in their 40s and 50s.
A Sliding Scale Between 110 and 145 Overnights
A parent with fewer than 146 overnights does not get the full shared-care calculation. Instead, the law adds a graduated adjustment. Family Law Software lists the adjustment as 10 percent for 110 to 114 overnights, then 9 percent at 115 to 119, 8 percent at 120 to 124, 7 percent at 125 to 129, 6 percent at 130 to 134, 4 percent at 135 to 139, and 2 percent at 140 to 145. The result cannot exceed what the basic guidelines would produce. Households that have watched family milestones shift since 1975 will see why calendars look so different now, and common adult regrets often involve time not spent with family.
The point of the table is to smooth out what Family Law Software calls the child support cliff, where a handful of overnights could swing support by a large amount. At 146 or more overnights, the standard shared-parenting formula applies with no adjustment. Many parents already know how much a few nights on the calendar can matter, as a piece on work-life balance points out. A column on what parents should not expect from adult children shows how long these family decisions can echo.
Minimum Support and Incarceration Rules
The law also touches low-income parents. The presumptive minimum support stays at $40 a month per child, with a cap of $120 a month. What moves is who qualifies: the income level for that presumption rises from 75 percent of the federal poverty guidelines to 100 percent. According to Family Law Software, the 2026 poverty level for a single person in Illinois is $15,960 a year. Parents with no income, those living only on means-tested benefits, and those unable to work because of a documented disability, incarceration or institutionalization keep a zero-dollar presumption, according to the law firm SDF Law.
A parent who is incarcerated for more than 180 consecutive days is presumed unable to pay. If nobody objects within 45 days of a notice of incarceration, support is set to $0. Support resumes at the statutory minimum 90 days after release unless someone asks the court to modify it based on actual ability to pay. Parole and work-release programs that allow a job are excluded.
What Parents Should Do Before Jan. 1
The new law does not rewrite existing support orders on its own. SDF Law notes that parents generally still need a court order to change support, and a post from attorney Russell Knight on the Illinois State Bar Association site confirms the Jan. 1, 2027 start. The next steps are practical: count actual overnights on the current parenting calendar, note whether any regular daytime care could be argued as an overnight equivalent, and gather income documents, since the law also requires parties to exchange written income documentation each year.
Family Law Software notes that its calculator can be set to a 2027 start year, but the official 2027 tables usually arrive in March, so early estimates use the 2026 basic obligation and gross-to-net tables. Anyone with a case pending should talk to a family law attorney, because the hearing date and the specifics of each order will decide which rules apply. Hastings has described the goal as keeping families from spending thousands of dollars fighting over formulas, a point also made in the earlier Senate announcement.
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This article was produced with AI assistance and edited for accuracy against the sources linked above.
Image: PhilDaBirdMan – CC0/Wikimedia Commons
