Key takeaways:
- Illinois has used an “income shares” model since July 1, 2017: support is based on both parents’ combined net income, not a flat percentage of one parent’s income.
- If each parent has the child 146 or more overnights a year, a shared-care formula applies (the basic obligation is multiplied by 1.5, then split and offset).
- From January 1, 2027, Public Act 104-733 extends shared-care rules down to 110 overnights and raises the income limit for the $40 minimum order. Existing orders do not change automatically.
- Support usually runs to age 18, or until high school graduation or age 19 (whichever comes first) if the child is still in high school.
- Rockford cases are filed at the Winnebago County Courthouse, 400 West State Street.
Last reviewed: October 22, 2026. This article is general information about Illinois law, not legal advice. Child support depends on detailed income calculations, so talk to a licensed Illinois attorney or use the official state tools for your own case.
If you are a parent in Rockford or anywhere in Winnebago County trying to figure out child support, the first thing to know is that many websites still describe Illinois’s old system, where the paying parent owed a fixed percentage of income. That system ended in 2017. Here is how support is calculated today, what changes in 2027, and where to get help locally.
Contents
- How Illinois calculates child support
- Child support calculator
- Shared parenting time
- What changes on January 1, 2027
- Costs on top of basic support
- Changing or enforcing an order
- Getting help in Rockford
- FAQ
How Illinois calculates child support
Under 750 ILCS 5/505, Illinois uses the income shares model. In plain terms:
- Find each parent’s net income. Courts usually use the “standardized” net income from the Illinois Department of Healthcare and Family Services (HFS) conversion table, which converts gross income to net using standard tax assumptions. In some cases an individualized net income calculation is used instead.
- Add them together. The combined net income and the number of children give a basic support amount from the HFS income shares schedule.
- Split it by income share. Each parent is responsible for their percentage of the combined income. If one parent earns 60% of the total, they owe 60% of the basic amount.
- The parent with fewer overnights pays their share to the other parent, who is presumed to spend their own share directly on the child.
Try the official estimator: HFS publishes a free online child support estimator and the current schedules. Its result is an estimate only; the judge sets the actual amount and can deviate from the guidelines if applying them would be inappropriate.
Low-income parents are treated differently. Under current law, a parent whose income is at or below 75% of the federal poverty guideline for one person is presumed to owe a minimum of $40 per month per child. A $0 order is presumed appropriate (but can be challenged) for a parent with no income other than means-tested public benefits, or who cannot work because of a medically proven disability, incarceration or institutionalization.
Illinois Child Support Calculator (2026 Schedule)
This calculator applies the Illinois income shares guideline (750 ILCS 5/505) using the HFS Schedule of Basic Obligations in effect since March 20, 2026. Enter each parent’s monthly net income. If you only know gross pay, convert it first with the HFS 2026 gross-to-net income conversion table, or use the official HFS Child Support Estimator.
Coming January 1, 2027: Public Act 104-733 lowers the shared physical care threshold from 146 to 110 overnights, with a graduated increase for the parent with 110 to 145 overnights (10% at 110-114 down to 2% at 140-145), and raises the low-income minimum-order threshold from 75% to 100% of the federal poverty guideline. This calculator still applies the 2026 rules.
Estimate only, not legal advice. Courts can deviate from the guidelines and add health insurance, child care and other expenses. Talk to an Illinois family law attorney about your case.
Shared parenting time
Under current law, if each parent has the child for 146 or more overnights a year, the “shared physical care” formula applies:
- The basic support amount is multiplied by 1.5, to reflect the cost of running two homes.
- Each parent’s share of that amount is multiplied by the percentage of time the child spends with the other parent.
- The two results are offset, and the parent with the higher amount pays the difference.
Overnights therefore matter a great deal. Your parenting schedule and your support calculation are closely linked.
What changes on January 1, 2027
Public Act 104-733 (Senate Bill 3524) amends Sections 505 and 510 and takes effect January 1, 2027. The main changes:
| Topic | Until Dec 31, 2026 | From Jan 1, 2027 |
|---|---|---|
| Shared physical care threshold | 146+ overnights each | 110+ overnights each |
| 110 to 145 overnights | Standard formula | Shared formula with a graduated adjustment (10% at 110–114 overnights down to 2% at 140–145), never more than the standard guideline amount |
| $40 minimum order applies at | Income up to 75% of the federal poverty guideline | Income up to 100% of the federal poverty guideline |
| Incarceration | Parent must seek a modification | New notice procedure that can set support to $0 for incarceration over 180 days |
Existing orders do not update themselves. If you think the new rules would change your support, you still need to ask the court for a modification.
Costs on top of basic support
The court can also divide, usually in proportion to income:
- Health insurance premiums for the child and uncovered medical, dental and vision costs
- Reasonable child care costs related to work or education
- Extracurricular and school expenses
College expenses are handled separately, under 750 ILCS 5/513.
Changing or enforcing an order
Either parent can ask the court to modify support after a substantial change in circumstances, such as a major change in income or parenting time. Support generally lasts until the child turns 18, or until the earlier of high school graduation or age 19 if the child is still in high school.
If support is not being paid, the HFS Division of Child Support Services can help with income withholding and enforcement, or you can file a petition with the court. Support is usually paid through the State Disbursement Unit so that payments are recorded.
Getting help in Rockford
We do not recommend or rank specific law firms. For local help:
- Winnebago County Courthouse (17th Judicial Circuit): 400 West State Street, Rockford, IL 61101. The court lists a temporary entrance at 403 Elm Street, one block south, so check before you go. The Circuit Clerk’s office is in Room 108.
- Self-Help Center: Room 304 (in the law library), 815-319-4526. Navigators help with forms and procedures but cannot give legal advice.
- Fee waivers: if you cannot afford filing fees, the 17th Judicial Circuit explains how to apply for one.
- Illinois Legal Aid Online: free guides, forms and a directory of legal aid organizations.
- Choosing a lawyer: confirm that any attorney is licensed and in good standing with the Illinois Attorney Registration and Disciplinary Commission (ARDC).
Related guides
FAQ
Is Illinois child support still 20% of income for one child?
No. The percentage guidelines were replaced on July 1, 2017 by the income shares model, which uses both parents’ net incomes.
How long does child support last in Illinois?
Usually until the child turns 18, or until the earlier of high school graduation or age 19 if the child is still in high school. College expenses are handled separately.
Does 50/50 parenting time mean no child support?
Not necessarily. With shared physical care, the formula offsets each parent’s obligation, so the higher earner may still pay the difference.
Will the 2027 law change my current order?
Generally not. Existing orders stay in place until a court modifies them, so you would need to file a petition. One exception: the new incarceration procedure can reduce support to $0 without a court hearing if a notice is filed and no one objects within 45 days.
Sources: 750 ILCS 5/505; Public Act 104-733 (SB3524); Illinois HFS Child Support Services; Winnebago County Circuit Court (17th Judicial Circuit).
