Illinois Child Support Calculator

Free instant estimate based on Illinois's Income Shares model (750 ILCS 5/505)

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Select a state and enter your monthly gross income to see an estimated child support payment based on net income.

How Illinois Calculates Child Support

Illinois calculates child support using the Income Shares model as established under 750 ILCS 5/505 of the Illinois Marriage and Dissolution of Marriage Act. This model is based on the principle that children should receive the same proportion of parental income that they would have received if the family had remained intact. Both parents' net incomes are combined and applied to the Illinois child support guidelines table to determine the total support obligation for the children.

In 2017, Illinois transitioned from a percentage-of-income model to the current Income Shares approach. The updated model accounts for the actual parenting time each parent has with the child. The number of overnights directly affects the support calculation, as each parent is assumed to incur direct costs for the child during their parenting time. This shared parenting adjustment provides a more equitable calculation that reflects the real-world expenses of both parents.

The total support obligation is divided between the parents in proportion to their respective shares of the combined net income. Additional expenses such as health insurance premiums, childcare costs, and extraordinary medical expenses are allocated separately and added to the basic support amount. The court may also deviate from the guidelines when warranted by special circumstances, such as a child with special needs or significant educational expenses.

Frequently Asked Questions

How does Illinois calculate child support under 750 ILCS 5/505?
Illinois uses an Income Shares model under 750 ILCS 5/505. Both parents' net incomes are combined and applied to the Illinois child support guidelines table to determine the total support obligation. Each parent is responsible for their proportional share of that obligation based on their percentage of the combined income.
What is considered net income for Illinois child support?
Net income in Illinois is gross income minus federal and state income taxes, Social Security and Medicare taxes, mandatory retirement contributions, union dues, health insurance premiums, prior child support or maintenance obligations, and certain other deductions allowed by statute. Gross income includes wages, commissions, bonuses, self-employment income, investment income, and other sources.
Does parenting time affect Illinois child support?
Yes. Since 2017, Illinois uses a shared parenting income model that accounts for the number of overnights each parent has with the child. The more overnights the paying parent has, the lower the support obligation. The adjustment is built into the guidelines and reflects the direct costs each parent incurs during their parenting time.
What additional expenses are included in Illinois child support?
Beyond the basic support obligation, Illinois courts may allocate additional expenses including health insurance premiums, extraordinary medical expenses, childcare costs, extracurricular activities, and educational expenses. These are typically divided between parents in proportion to their respective incomes.
Can Illinois child support be modified?
Yes. Illinois allows modification of child support orders when there has been a substantial change in circumstances. This includes significant changes in either parent's income, changes in custody or parenting time, changes in the child's needs, or the passage of time since the original order. A modification must be filed with the court that issued the original order.

Important Legal Disclaimer

The information provided on SupportCalc is for general informational and educational purposes only. Nothing on this website should be taken as legal advice. Child support calculations are estimates based on publicly available state guidelines and may not reflect the exact amount ordered by a court. Every case is unique, and many factors can affect the final support order. Please consult with a qualified family law attorney in your jurisdiction for advice specific to your situation.