Illinois Child Support Guidelines

Illinois operates under the Percentage of Income model, one of 6 U.S. states using this framework. For a parent supporting one child, the base guideline applies roughly 20% of income, scaling to 28% for two children and 32% for three. That places Illinois at rank #4 of 51 states by single-child base percentage. Unlike capped states, there is no statutory income ceiling — the formula applies to the full reported income before deductions. Median household income across Illinois is $72,205 annually, which shapes the real-world dollar obligations families face under these percentages.

On the enforcement side, the Illinois child support program manages 524,000 active cases and collected approximately $1,100 million in the most recent OCSE reporting year. The state's collection rate of 57.6% compares to a national average of 60.6% across reporting states — placing Illinois at rank #37 of 51 on collection efficiency, and rank #8 by caseload volume (national average: 285,686 cases per state). Paternity is established in 94.7% of Illinois cases, compared to 94.9% nationally — a critical step because child support orders cannot be enforced without legal parentage on record. Orders are in place for 73.1% of the caseload.

Context matters when interpreting these numbers. A higher percentage-of-income figure does not automatically mean higher dollar obligations — the underlying income brackets, deductions, parenting-time adjustments, and self-support reserves vary meaningfully between states. Illinois allows a parenting time adjustment, which can materially reduce the base obligation when the non-custodial parent exercises substantial overnight time. Our interactive Illinois calculator applies these guidelines to specific income and custody scenarios. Data sources: OCSE FY2022 Annual Report, Illinois Revised Statutes, and Census ACS 2022.