Illinois Child Support Calculator

Child support calculator

Simple Child Support Calculator

For a simple and easy calculation of child support in Illinois, we recommend using the official Illinois Child Support Estimator.

The official Illinois Child Support Estimator is quite simple and easy to use. You can also expect it to be accurate and kept up to date in 2024.

For the state of Illinois, we advise against using a different calculator as the results may be innacurate or misleading.

Overnights Calculator for Illinois

According to Illinois child support guidelines, payment amounts depend on how many overnight stays a child has with each parent annually.

Use this overnights calculator to work out how many nights of care you provide.

Calculate annual overnight stays

Regular nights
Vacation nights each year*
183 overnight stays per year.
50.0% of parenting time.

* Vacation nights are all nights when the regular schedule does not apply.

How Child Support is Calculated in Illinois


Child support payments in Illinois are calculated using the income shares method. Payments depend on the combined incomes of the parents as well as the number of children. A larger combined income or more children usually means greater payments.

The amount paid or received by an individual parent also depends on income and parenting time percentages.

  • If your income percentage (your share of combined income) is higher than your care percentage (share of parenting time), you are probably the payer.
  • The receiver is normally the parent with a care percentage above their income percentage.

Illinoisans paying the most child support have high incomes and rarely look after their children. On the flipside, the biggest receivers are parents who (a) work little (b) have their kids nearly all the time and (c) have a high earner as the other parent.

The way that child support is calculated in Illinois is complex and changes every year. Payments are, for example, affected by tax rules, any spousal maintenance payments, social security benefits, child care expenses, and extraordinary expenses.

The State of Illinois has determined that had the parties stayed married, a portion of their joint income would be used for their children and the same principle should apply when they are divorced. The State of Illinois has employed economists that developed this calculation based on this philosophy. It is a complicated formula with several components.

Faye Lyon

Illinoisan child support guidelines apply to the whole state, including the cities of Chicago, Aurora, Naperville, Joliet, Rockford and Springfield. Variations in support payments may be made by the agreement of parents or at the discretion of a judge presiding over your case.

Payment Calculators by State

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