Illinois Child Support Guide 2026: How the Guidelines Calculate Your Amount

Parents facing a support case in Illinois usually want one number: how much will the court order? A statewide guideline formula turns both parents’ incomes and the number of children into a presumptive monthly amount. This guide explains how it works. Run your own figures in the free Illinois child support calculator.

How is child support calculated in Illinois?

Illinois adds both parents’ monthly net incomes together, looks up the basic support obligation for that combined income and number of children on the official HFS schedule, then charges the paying parent their percentage share of the total. Child care and health insurance costs are added and split by the same percentages.

The steps come from Section 505(a)(1.5) of the Illinois Marriage and Dissolution of Marriage Act (750 ILCS 5/505). Since July 1, 2017 Illinois has used this “income shares” model, which estimates what parents in one household would spend on their children, then divides that cost when they live apart — replacing the old flat percentage-of-the-payer’s-income system.

What is the Illinois child support schedule for 2026?

The Schedule of Basic Child Support Obligations, published by the Illinois Department of Healthcare and Family Services and revised effective March 20, 2026, lists a monthly basic obligation for combined net incomes and one to six children — for example, $1,674 for two children at $5,000 of combined monthly net income.

The full schedule runs to more than 520 rows in $50 income bands, and the dollar tables are updated annually — older calculators using the 2025 schedule will be slightly off. Above the top of the schedule, the obligation cannot be set lower than the highest schedule amount, but the court may order more.

Does Illinois use gross or net income for child support?

Illinois uses monthly net income. Each parent starts with gross income from all sources, then Illinois law subtracts a standardized tax amount — federal and state income tax plus Social Security and Medicare — using conversion tables published by the state. An individualized tax calculation can be used instead in some cases.

So two parents on the same salary can owe different amounts — their tax situations differ, and the children’s dependency exemptions sit with the parent who has the majority of parenting time. Bonuses and overtime count as income too, and if a parent is voluntarily unemployed or underemployed, a court can base support on potential income instead.

How much is child support in Illinois for two children?

Take parents earning $5,000 and $3,000 gross per month with two children, $600 of work-related child care and a $250 children’s health premium. Their estimated net incomes are about $4,199 and $2,592 — a combined $6,791. The schedule obligation is about $1,939, and the higher earner pays roughly $1,725 a month.

Your number moves with each input — higher child care raises it; shared care with both parents over 146 overnights changes the formula entirely, as the next section explains. Courts use actual net income figures from the state’s conversion table, not estimates, so treat any online figure as a close preview rather than the exact order.

Does shared custody reduce child support in Illinois?

Once each parent has the children for at least 146 overnights a year, a different formula applies: the basic obligation is multiplied by 1.5, each parent’s share is multiplied by the other parent’s share of parenting time, and the two amounts are offset. The difference owed is usually far smaller.

Below 146 overnights for either parent, the 2026 guidelines make no parenting-time adjustment at all — the paying parent’s time only matters once that threshold is crossed. A graduated adjustment covering 110 to 145 overnights is scheduled to take effect on January 1, 2027, but it is not part of the 2026 calculation.

Are child care and health insurance added to Illinois child support?

Yes. Reasonable child care costs that allow a parent to work or attend training, and the children’s portion of a health insurance premium, are allocated between the parents in proportion to their net incomes and added on top of the basic obligation, so they can add hundreds of dollars a month in higher-cost cases.

Two details catch parents out: child care totals are reduced by the federal child care tax credit before they are split, and health coverage only counts as reasonably priced up to 5% of the providing parent’s gross income. Which parent actually pays the premium also matters — the other parent’s share is added to, or deducted from, the support amount accordingly.

What happens at very low or very high incomes in Illinois?

At the low end, a paying parent whose gross income is at or below 75% of the federal poverty guidelines is presumed to owe a minimum of $40 per child monthly, capped at $120 total. Above the schedule, courts may set higher amounts but never below the schedule’s top figure.

At the very bottom, the presumption flips the other way: a parent with no gross income, who receives only means-tested public assistance, or who cannot work because of a medically proven disability, incarceration, or institutionalization is presumed to owe $0. Both the minimum and the $0 presumption can be challenged on the facts of the case.

Can an Illinois court order more or less than the guideline amount?

Yes. The guideline amount is presumed correct, but a court that finds it inappropriate in a particular case may set a different amount — for example because of a child’s special medical or educational needs, a parent’s other support obligations, or the parents’ own written agreement — and must explain its reasons.

Deviations are the exception — most orders land on the guideline figure, so a careful estimate is a realistic preview of the outcome.

How can you estimate your own Illinois child support?

Start with both parents’ gross monthly incomes, the number of children, the paying parent’s overnights per year, your monthly child care cost and the children’s health premium, and enter them in the Illinois child support calculator. It estimates net incomes, applies the 2026 schedule and income shares, and handles the shared-care offset.

See also our Illinois income tax calculator (the flat 4.95% state tax forms part of a court’s net-income conversion) and the paycheck calculator.

Frequently Asked Questions

When does child support end in Illinois?

Generally at age 18. If the child is still attending high school, support usually continues until graduation or the child’s 19th birthday, whichever comes first. It can continue for a child with disabilities, or longer by written agreement.

Can Illinois child support be modified?

Yes. Either parent can ask the court to modify an order after a substantial change in circumstances — a job loss, a raise, a change in parenting time, or an update to the guideline schedule itself.

Is child support taxable in Illinois?

No. It is not taxable income for the parent who receives it, and the parent who pays it cannot deduct it.

Who pays child support if both parents earn the same?

With primary custody and equal incomes, the non-custodial parent still pays their 50% share — the custodial parent’s share counts as spent directly on the children. With true shared care (146 or more overnights each) and equal incomes, the offset brings the basic payment close to zero, though child care and health premium shares still apply.

Disclaimer: This guide is general information and an estimate only — not legal advice. Support orders are set by the court under 750 ILCS 5/505 and may differ from any estimate here. For advice about your case, consult an Illinois family law attorney.