Illinois Child Support Calculator
Estimate monthly child support under Illinois's official guideline model. Updated for 2026.
Last reviewed July 2026 · Free · Nothing you enter is stored
Income Shares state
Before taxes. Include wages, self-employment, bonuses.
Every-other-weekend ≈ 80. Equal custody ≈ 182.
$0
estimated monthly child support ·
Guideline estimate, not a court order or legal advice. Courts may deviate based on your circumstances.
Compare with Illinois's official calculator ↗
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How Illinois calculates child support
Illinois uses the income shares model: both parents' incomes are combined, a basic support obligation is determined from the state's guideline schedule, and each parent is responsible for their proportional share. The parent without primary custody typically pays their share to the other household.
Governing law: 750 ILCS 5/505 — Converted from percentage-of-obligor to income shares July 1, 2017; uses standardized net-income conversion tables and a 146-overnight shared-parenting formula.
Illinois publishes an official calculator that applies the full guideline schedule: official Illinois child support calculator. Use ours for a quick, private estimate and theirs when you need the exact worksheet figure.
Frequently asked questions
How is child support calculated in Illinois?
Illinois uses the income shares model: both parents' incomes are combined, a basic support obligation is determined from the state's guideline schedule, and each parent is responsible for their proportional share. The parent without primary custody typically pays their share to the other household. The guideline is set by 750 ILCS 5/505.
Is this the exact amount a Illinois court will order?
No — this is a guideline estimate. Courts start from the guideline amount but can deviate for factors like extraordinary medical costs, special needs, other support obligations, or agreements between parents. For an official figure, use the state’s own calculator linked on this page or consult a family law attorney.
Does parenting time affect child support in Illinois?
In most states, including under most guideline models, substantial parenting time (often above roughly 20–30% of overnights) reduces the paying parent's obligation. Our calculator applies a simplified parenting-time adjustment; Illinois's courts apply their own specific rules, so treat shared-custody results as rough estimates.
What income counts for child support in Illinois?
Generally all income: wages, self-employment, bonuses, commissions, and often investment income. Illinois's guideline applies to net (after-tax) income — our calculator approximates net income from the gross figures you enter. Courts may also impute income to a parent who is voluntarily unemployed or underemployed.
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