Illinois Child Support Calculator
General information, not legal advice.
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How Illinois sets child support
Illinois sets child support by the income shares method under 750 ILCS 5/505(a). The rule has been in force since March 20, 2026.
- Coverage
- Calculated by the support engine
- Method
- income shares
- Source
- 750 ILCS 5/505(a) (Illinois Marriage and Dissolution of Marriage Act); HFS annual Income Shares Schedule of Basic Child Support Obligations and Gross to Net Income Conversion Table (standardized tax amounts) promulgated under 505(a)(1) and (a)(3)(C)(II); 2026 Addendum (J. Venohr, Mar. 13, 2026)
- In force from
- March 20, 2026
- Rule version
- 2026-03-20
- Inputs it needs
- Children
- Optional inputs
- Parent A gross monthly, Parent A net monthly, Parent B gross monthly, Parent B net monthly, Majority time parent, Overnights A, Obligor at or below 75pct poverty
Rule details as of 2026-10-25. The calculator above reads the current rule. Where the rule gives no formula, no figure is shown.
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