Child support · IL
Illinois child support calculator
750 ILCS 5/505 and the Department of Healthcare and Family Services tables, from gross pay to the monthly order.
Rules read on official Illinois pages on · Checked by Radif Partners · How we calculate
- Model
- Income shares
- Income counted
- Net income
- Shared parenting
- From 146 overnights
- 1 child, $5,000 / $3,000
- $903
- a month, rules of March 20, 2026
An Illinois parent who nets $4,000 a month, next to a co-parent netting $2,000, owes $1,205 a month for two children under 750 ILCS 5/505, before child care and the children's health premium. The figure comes from the Department of Healthcare and Family Services schedule that took effect on March 20, 2026: $1,808 for two children in the $5,975 to $6,024.99 bracket, split two thirds to one third. Illinois works on net income, and HFS publishes a standardized gross-to-net conversion table every year so that both parents' taxes are figured the same way. Time with the children changes nothing until each parent has 146 overnights; then the basic amount is multiplied by 1.5 and cross-credited, which brings this order to $723. A very low earner owes a minimum of $40 per child instead.
Guideline child support in Illinois, per month
$903
$10,830 a year
| Combined monthly net income | $8,000 |
| Basic obligation in the HFS income shares schedule, 1 child | $1,444 |
| Paying parent’s share of net income | 62.5% |
Estimate under the Illinois guideline as published, from the incomes you enter. Deviations, imputed income, other children and the judge's findings can change the order. How this is calculated.
Brackets that change every spring
Since 2024 HFS revises both of its tables every year, and the current pair took effect on March 20, 2026. The schedule is printed as $50 brackets of combined net income, from $25 up to $27,374.99 a month, so there is no rounding question: the amount of the bracket that contains the income applies. The 2026 update pushed the ceiling up and redrew the first tier around 75% of the federal poverty guideline for one person.
Gross pay goes through a conversion table first
Section 505(a)(3) defines net income as gross income minus a standardized tax amount: federal and Illinois income tax for a single filer with the standard deduction, plus Social Security and Medicare, with the dependency claim given to the parent who has the majority of parenting time. HFS turns that into its Gross to Net Income Conversion Table, with different columns for the two parents. A parent with unusual taxes can ask the court for an individualized amount instead. The calculator on this page expects net figures, so read them from the HFS table or from the court's finding before you type. Maintenance ordered in the same case comes off the payer's net income and is added to the recipient's before support is figured.
When 146 nights each changes the order
Shared physical care under § 505(a)(3.8) requires 146 or more overnights a year with each parent. Below that, extra visits have no effect: at 145 nights our paying parent still owes $1,205. At 146, the basic obligation is multiplied by 1.5, each parent's part is weighted by the time the child spends with the other one, and the two figures are offset, giving $723. HFS publishes a separate worksheet for this case.
The floor and the ceiling
Section 505(a)(3.3a) presumes a minimum order of $40 per child each month, $120 at most, for a parent whose gross income is at or under 75% of the poverty guideline for one person. The 2026 HFS addendum puts that at $998 gross a month, about $884 net, and the calculator applies the minimum at or below that net figure. A parent netting $850 with three children owes $120. A parent with no income, only means-tested benefits, a proven disability or a prison term is presumed to owe nothing. At the other end, once combined net income passes $27,374.99, the judge sets support case by case but cannot go below the top bracket: with $30,000 and $5,000 and two children, the calculator keeps the $5,210 top amount and the higher earner's share of it, $4,466. Spousal maintenance has its own guideline in Illinois, covered on the Illinois maintenance page.
The Illinois guideline this calculator applies
| Rule | Illinois |
|---|---|
| Model | Income shares, combined monthly net income schedule (HFS Schedule of Basic Obligations) |
| Income counted | Net income: after income taxes and mandatory deductions, as the state defines it. |
| Official schedule | $25 to $27,375 of combined income a month, 547 rows |
| Shared parenting | Cross-credit formula from 146 overnights a year, basic amount × 1.5 |
| In force since | March 20, 2026 |
Monthly support for one paying parent, the other parent without income
| Paying parent’s monthly income | 1 child | 2 children | 3 children | 4 children |
|---|---|---|---|---|
| $2,000 | $461 | $702 | $848 | $948 |
| $3,000 | $691 | $1,053 | $1,272 | $1,421 |
| $4,000 | $921 | $1,378 | $1,656 | $1,849 |
| $5,000 | $1,110 | $1,674 | $2,006 | $2,241 |
| $6,000 | $1,211 | $1,808 | $2,142 | $2,393 |
| $8,000 | $1,444 | $2,137 | $2,507 | $2,801 |
| $10,000 | $1,686 | $2,499 | $2,938 | $3,282 |
| $12,500 | $1,949 | $2,850 | $3,303 | $3,689 |
| $15,000 | $2,269 | $3,302 | $3,806 | $4,251 |
| $20,000 | $2,784 | $4,119 | $4,836 | $5,402 |
How the amount is set. The HFS schedule is published as $50 income brackets (e.g. 5,975.00 - 6,024.99); 750 ILCS 5/505(a)(1.5)(C) says to select the corresponding amount for the parties' combined monthly net income, so the amount of the bracket containing the income applies. source
Income. Gross income is all income from all sources except means-tested benefits (TANF, SSI, SNAP) and benefits or income received for other children in the household; social security disability/retirement benefits paid for the subject child count in the disabled or retired parent's income (750 ILCS 5/505(a)(3)(A)). Net income is gross income minus the standardized tax amount (federal and state income tax for a single person with standard deduction, plus Social Security and Medicare; the parent with the majority of parenting time is deemed to claim the child), read from the HFS Gross to Net Income Conversion Table, or minus an individualized tax amount by stipulation or court determination (505(a)(3)(B)-(E)). Net income is then reduced by multi-family adjustments and spousal maintenance (505(a)(3)(F)).
Above the table. 750 ILCS 5/505(a)(3.5): if combined adjusted net income exceeds the highest level of the schedule, the court may use its discretion, but the basic obligation may not be less than the amount at the highest level of the schedule (bracket 27,325.00-27,374.99 in the 2026 schedule).
Parenting time. 750 ILCS 5/505(a)(3.8): if each parent exercises 146 or more overnights per year, the basic obligation is multiplied by 1.5; each parent's share (by percentage of combined net income) is multiplied by the percentage of time the child spends with the other parent, and the two amounts are offset, the parent owing more paying the difference. HFS publishes a Shared Physical Care Support Obligation Worksheet.
Child care and health care. court may order; prorated by share of combined net income and may be added to the basic obligation premium attributable to the child added to the basic obligation and allocated by net income 750 ILCS 5/505(a)(3.7): reasonable child care for work, education or job search is prorated by each parent's share of combined net income, minus the federal child care tax credit if allowed. (a)(4)(D)-(E): the health insurance premium attributable to the child (or premium divided by persons covered, times children covered) is added and allocated by net income; if the obligor pays it, the obligee's share is deducted from the obligor's support, if the obligee pays it, the obligor's share is added. (a)(3.6): extracurricular and school expenses may be ordered in addition.
Low incomes. Low-income adjustment is built into the schedule: the 2026 Addendum says the first tier aligns with after-tax income at 75% of the 2026 FPG for one person. Below that threshold the $40-per-child minimum order applies (505(a)(3.3a)).
When support ends. For 750 ILCS 5/505, 'child' includes any child under 18 and any child aged 19 or younger who is still attending high school. source
The state also runs its own official child support calculator; use it, or the court's worksheet, for a filing.
Worth knowing in Illinois
- Illinois switched from a percentage-of-obligor-net-income guideline to income shares effective July 1, 2017 (Public Act 99-0764). source
- Since 2024 HFS updates both the Gross to Net Income Conversion Table and the Schedule of Basic Obligations every year; the current versions took effect March 20, 2026. source
- The 2026 schedule was extended to combined net income up to $27,374.99 per month (previously $26,724.99). source
- If a parent has insufficient work history, potential income is presumed to be 75% of the HHS poverty guideline for a family of one (505(a)(3.2a)); incarceration is not voluntary unemployment. source
- In split physical care, two worksheets are computed as if each parent's child were the only child, and the smaller obligation is subtracted from the larger (505(a)(3.9)). source