Illinois Child Support Calculator
Calculate child support in Illinois using the state's official Income Shares Model. Includes custody adjustments, health insurance credits, and childcare deductions.
Illinois divorces typically cost 28% less than the national average of $12,900.
Child Support in Illinois
- Formula
- Income Shares Model
- Income cap
- None specified
- Equal parenting presumption
- No
- Property system
- Equitable distribution
Child Support Calculator in Illinois: What You Should Know
Illinois uses the Income Shares Model applied to net income, defined as each parent's gross income minus federal and state income taxes, Social Security, Medicare, and mandatory union dues. The net income approach means Illinois calculations are lower than in states using gross income at the same earnings level. Illinois child support guidelines include detailed tables for different income levels and numbers of children. The state also has a significant parenting time adjustment: when the paying parent has the children for more than 146 nights per year, a shared parenting formula applies that substantially reduces the basic support obligation.
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Locked to Illinois on this page.
Use your gross (before-tax) monthly income. If you are paid annually, divide by 12.
Use their gross (before-tax) monthly income. If they are paid annually, divide by 12.
This estimate is for planning purposes only and does not constitute legal or financial advice. Consult a licensed family law attorney in your state for guidance specific to your situation.
Child Support in Illinois - Frequently Asked Questions
How is child support calculated in Illinois?
Illinois uses the Income Shares Model to calculate child support. Both parents' gross incomes are combined, and each parent's share of the total obligation is proportional to their share of the combined income.
Can child support be modified in Illinois?
Yes. Either parent can request a child support modification if there has been a substantial change in circumstances, such as a significant change in income, change in custody arrangements, or changes in the child's needs. Courts in Illinois typically require a change of at least 15-20% in the support amount to justify modification.
Does custody arrangement affect child support in Illinois?
Yes. Parenting time is a significant factor in child support calculations. When a parent has the children for a substantial portion of time (typically 40% or more overnights per year), child support is adjusted to reflect the additional direct costs that parent bears.
Is there an income cap for child support in Illinois?
Illinois does not set a specific income cap in its child support formula. However, courts have discretion to deviate from the guideline amount in cases with very high incomes.
How long does child support last in Illinois?
Child support in Illinois typically continues until the child turns 18 or graduates from high school, whichever is later. Support may continue longer if the child has a disability or if the parents agree to extend support for college expenses.
This estimate is for planning purposes only and does not constitute legal or financial advice. Consult a licensed family law attorney in your state for guidance specific to your situation.