Illinois Child Support Calculator
Enter both parents' incomes, number of children, and parenting time to estimate the Illinois monthly child support obligation under the Income Shares model. Consult a family law attorney for a binding order.
- 20%
- 1-child base rate
- #4 of 51
- base-rate rank
- No cap
- income ceiling
- 85.1%
- cases with a support order
$1,203/mo
One-child base rate at Illinois's median income
20% of $72,205, the Census ACS 2022 median household income for Illinois, divided across twelve months, 26% above the median state. An index for comparing states, not a case estimate: guidelines apply to the obligor's income, or to combined parental income under the Income Shares model, and a court sets the actual order. How this is derived.
The verdict
Illinois carries one of the highest one-child base rates nationally.
According to Illinois Title IV-D guideline publication, last checked 2026.
- 20%
- published 1-child starting rate
- 85.1%
- of cases have a support order
Ranks describe published guideline starting rates across this portal's 51-jurisdiction table, not court outcomes or collection performance.
National context
Higher-band view: where Illinois's one-child start sits
Each bar counts jurisdictions with a published one-child base rate in that 3-point guideline band. Illinois is marked in its own band; counts are exact from the 51-jurisdiction dataset.
Illinois's 20% published one-child starting rate is higher than 42 of 51 recorded state rates. This comparison describes the published starting percentage, not a complete child-support estimate.
Source: Published state child-support guideline records in PlainChildSupport's 51-jurisdiction dataset
Income Shares peers by one-child starting rate
Source: State Title IV-D guideline publications compiled in PlainChildSupport states.base_pct_1child filtered by formula_type · 2026 Peer board lists up to 10 Income Shares states sorted by published one-child starting rate. Counts match SELECT COUNT on the live states table.
Higher one-child starting rate
Illinois calculator on a higher starting-rate schedule
Illinois's published 20% one-child base sits in the higher third (#4 of 51).
Illinois's 20% one-child start sits in the higher third of published schedules (#4 of 51). The Income Shares form below applies that schedule plus any recorded income ceiling or parenting-time credit — still an estimate, not an order.
Sources: Illinois Child Support Guidelines · HHS OCSE Annual Report to Congress (Form 157) · estimate only; a court order requires the official worksheet.
Enter the details above to estimate Illinois child support.
This calculator uses Illinois's Income Shares guidelines.
Illinois Guideline Summary
~20%
1 Child
~30%
2 Children
~36%
3 Children
None
Income Cap
Questions about this Illinois estimate
Why does Illinois's one-child start read high nationally?
Illinois's 20% published one-child starting rate is higher than 42 of 51 recorded state rates. This comparison describes the published starting percentage, not a complete child-support estimate.
Does Illinois publish an income ceiling for this estimate?
No income ceiling is recorded in this portal's 2026 Illinois guideline dataset. The official worksheet remains the authority for a binding calculation.
Calculators nearest Illinois's 20% start
Sorted by absolute gap in published one-child starting rate among states with a verified interactive calculator. Not a recommendation of which worksheet to file.
Read our methodology - how this data is sourced, computed, and verified.
Source: U.S. Office of Child Support Services (OCSS) - HHS Child support enforcement caseload and collections · 2025