Illinois Child Support Calculator

Illinois uses the income shares model. Illinois uses the Income Shares Model (effective July 1, 2017, per Public Act 99-0764). Both parents' net incomes are combined to determine the total child support obligation based on a statutory schedule. Each parent's share is proportional to their percentage of the combined income. The non-custodial parent's share is typically paid as child support. Illinois updates the Gross-to-Net Income Conversion Table and Schedule of Basic Obligations annually (most recently revised March 5, 2025) (750 ILCS 5/505).

Gross income from all sources is typically used, including wages, salary, bonuses, commissions, self-employment income, rental income, investment income, Social Security benefits, unemployment benefits, and disability benefits. Courts may also impute income if a parent is voluntarily unemployed or underemployed.

Child support in Illinois generally continues until the child turns 18, or through high school graduation if the child is still in school. Some orders extend to age 19 or 21 depending on the state and circumstances (college support, special needs).

Yes, child support orders in Illinois can be modified when there is a substantial change in circumstances. Common reasons include significant income changes (job loss, promotion), changes in custody arrangement, changes in the child's needs, or changes in healthcare costs.

Illinois has enforcement mechanisms including wage garnishment, tax refund interception, license suspension (driver's and professional), bank account levies, contempt of court charges, and reporting to credit bureaus. Failure to pay can result in fines and jail time.