Illinois Child Support Calculator 2026
Illinois reads the basic child support amount from a state schedule, which this page does not reproduce. Enter both parents' incomes to see each parent's share of combined income and of insurance and childcare, then use the official Illinois source linked below for the schedule amount. Calculated privately in your browser.
Estimate only — the court or the child support agency sets the order. Official source: Illinois HFS child support estimator.
Illinois uses the income shares model for child support: a basic obligation is read from the state schedule using both parents' combined income and the number of children, then divided by each parent's share of that income. This page calculates the shares; the schedule amount comes from the official Illinois source.
How Illinois Child Support Is Calculated
The National Conference of State Legislatures lists Illinois among the income shares states. The calculation has four steps: add both parents' incomes; find the basic obligation for that combined income and number of children in the Illinois schedule; divide it between the parents in proportion to their incomes; then apply the worksheet's adjustments.
Illinois starts from each parent's net income as the state defines it, which is not the same as take-home pay on a payslip; the worksheet lists the deductions allowed.
| Step | On this page? |
|---|---|
| Each parent's share of combined income | Yes — exact arithmetic |
| Basic obligation from the Illinois schedule | No — read it from the official source |
| Health insurance and childcare split | Yes — divided by income share (750 ILCS 5/505(a)(3.7) and (4)) |
| Parenting-time adjustment | No — made on the worksheet or by the court |
| Low-income and high-income rules | No — set by the Illinois guidelines |
Worked Example: Illinois Income Shares
With the default figures, the paying parent has $5,000 a month and the other parent $3,000. Combined income is $8,000, so the paying parent's share is 62.5% and the other parent's is 37.5%. With a $150 health insurance premium and $200 of work-related childcare, an income-share split puts $93.75 and $125.00 on the paying parent. To finish the calculation you would look up $8,000 of combined income and 2 children in the Illinois schedule and apply those shares.
Insurance, Childcare and Parenting Time in Illinois
Illinois divides the children's health insurance premium and work-related childcare between the parents in proportion to their incomes (750 ILCS 5/505(a)(3.7) and (4)), so the paying parent's share of those costs is the same percentage as the income share above. Which costs count, and any limits, are set on the worksheet.
Any adjustment for parenting time (overnights) is made on the state worksheet or by the court and is not estimated here.
Estimate Only: Who Sets the Illinois Order
This page gives an estimate only — the court or the state child support agency sets the order, and either can depart from the guideline where the law allows. Before relying on any figure, run the same figures through the Illinois HFS child support estimator.
If your income, the parenting schedule or the children's needs change, ask the court or the agency to review the order, and keep paying the ordered amount until it is changed. Last updated: October 2026.
Frequently Asked Questions
How is child support calculated in Illinois?
Illinois uses the income shares model. A basic obligation is read from the Illinois schedule using both parents' combined income and the number of children, then divided between the parents in proportion to their incomes. Insurance, childcare and parenting time are handled on the state worksheet, and a court or the child support agency sets the final amount.
Does this calculator give the Illinois guideline amount?
No. It calculates each parent's share of combined income and of insurance and childcare costs. The basic obligation comes from the Illinois schedule, which this page does not reproduce. Use the official Illinois source linked on the page for the schedule amount.
What income does Illinois use for child support?
Illinois works from each parent's net income as the state defines it, which is not the same as take-home pay. The official worksheet lists the deductions allowed; enter that net monthly figure for both parents.
How are health insurance and childcare handled in Illinois?
Illinois divides the children's health insurance premium and work-related childcare between the parents in proportion to their incomes (750 ILCS 5/505(a)(3.7) and (4)), so the paying parent's share of those costs is the same percentage as the income share above. Which costs count, and any limits, are set on the worksheet.
Who decides the final child support amount in Illinois?
A court or the state child support agency sets the order. Guideline figures are a starting point, and the decision-maker can depart from them where the law allows. An online estimate, including this one, is not an order.