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Free Illinois Child Support Calculator

Home > Illinois Child Support Calculator

Calculate your Illinois Child Support Payment and learn much more. Don't be satisfied with Child Support Calculators that only tell you the support amount.

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This is an example calculation. To see the same details for your case, go to our Illinois Child Support Calculator.


This is a sample Child Support calculation.

Click here to use our Illinois Child Support Calculator.

By using this calculator you expressly acknowledge that:
  1. No content is considered legal advice. Always consult an attorney.
  2. All content is based on Support Studies' views and interpretations of Illinois child support laws and the Illinois Child Support Guideline as of February 2013.
  3. The greatest care has been taken for accuracy relative to the Florida Child Support Formula. However, your results as calculated by the state of Florida may be different than the results presented here.

The Payment

The bottom line monthly child support payment is $560.00

This includes:
1) A base support payment of $560.00.

Other possible adjustments are not included here. Some are discussed later.
Where does that number come from?

His financial contribution to base child rearing.

Illinois sets his financial contribution to your child rearing expenses at $560.00 before medical insurance. This is 20.00% of his net income.

Neither your time nor his time with the children are a part of the calculation. However, in your case the payment averages to $36.72 each of your 183 days with the child.

Your financial contribution to base child rearing.

Illinois makes no mention of custodial spending on the children and neither custodial income nor non-custodial parenting time are inputs to the formula.

What, then, is your responsibility to the financial costs of child rearing?

For the purpose of this analysis, we will apply the same rules to you as the Illinois Legal Code applies to him. With net income of $2,800.00 applying the same rules to you results in a financial responsibility of $560.00, or 20.00% of your net income.

Using the Illinois Child Support formula as a benchmark for your financial contribution to child rearing results in the following:

He contributes $560.00 to your basic child rearing expenditures.
You directly contribute $560.00 to basic child rearing expenditures.
Your total direct spending on base child rearing comes to $1,120.00.

What about his child rearing expenditures?

The default Illinois formula does not adjust for any childrearing expenditures he makes during his 182 days with the child.

By default, his monthly support payment before insurance would still be $560.00 whether the child spends 0 days or 182 with him.

Note that the State of Illinois does allow for deviations due to shared parenting time, however these are at the discretion of the court.

How about food?

By comparison, the 2012 USDA estimated liberal food menu for 1 child is $9.93. In other words, each day the child is with him, you save approximately $9.93 and he spends $9.93 on food for the child.

And after food?

Considering that the default Illinois formula does not adjust payments based on his time with the child, after USDA estimated liberal food expenditures he has-$9.93 remaining of his $0 credit.

After food that's -$9.93 per child each of 182 days.

Annually, food alone leaves him with -$1,807.26 for childrearing expenditures relative to the $0 by which the state adjusts him payments for his time with the child.

Medical Premiums

You entered a total of $0 for medical insurance premiums. If there is no medical insurance the court may order it.

Note that if he pays for child-related health insurance directly, the expense is treated as a reduction in income. With 1 child, algebraically this implies that you contribute 20.00% of his direct spending on child-related health insurnace premiums through a reduction in child support received. On the other hand, our interpretation of the default Illinois guideline with respect to health insurance is that if you pay for child-related health insurance directly then by default he contributes 50.00% of your direct spending on child-related health insurnace premiums through an increase in child support paid.

Beyond our understanding of the 50% default payment, in addition, the Illinois Legal Code specifically states that "The court may order the obligor to reimburse the obligee for 100% of the premium for placing the child on his or her health insurance policy.

Anything Else?


Illinois law lists additional factors that may increase payments. "The court, in its discretion, in addition to setting child support pursuant to the guidelines and factors, may order either or both parents owing a duty of support to a child of the marriage to contribute to the following expenses, if determined by the court to be reasonable:

  • health needs not covered by insurance
  • child care
  • education
  • extracurricular activities."

This calculator and analysis focuses on the Illinois Child Support Guidelines default results. There is no default formula to handle these additional factors and they are not treated here.

Isn't that part of the base obligation?

Not necessarily.

Before any consideration for education, child care or extracurricular activities, Illinois already estimates 20.00% of your combined net income goes to base childrearing and health insurance.

Unless both parents have a savings rate of zero, that is a larger percent when looked at as a percent of expenditures. A deviation ordering increased payments for uninsured medical, child care, education or extracurricular activities would increase that percent further.

What about non-minor children?

Illinois may require child support payments even after your children become adults.

This may be "When the child is mentally or physically disabled and not otherwise emancipated.

It may also include education expenses after the child has become an adult.

We are aware of no other situation where the State of Illinois can require a parent to pay for the education expenses of adult children.

From a practical perspective, in the opinion of Support Studies in a case where college or other education expenses for an adult child has been ordered by the court, Illinois is effectively implying that the 20.00% of combined net income attributed by default to your household's child-rearing expenses did not include college savings.

According to Illinois law: "The educational expenses may include, but shall not be limited to, room, board, dues, tuition, transportation, books, fees, registration and application costs, medical expenses including medical insurance, dental expenses, and living expenses during the school year and periods of recess, which sums may be ordered payable to the child, to either parent, or to the educational institution, directly or through a special account or trust created for that purpose, as the court sees fit...The authority under this Section to make provision for educational expenses, except where the child is mentally or physically disabled and not otherwise emancipated, terminates when the child receives a baccalaureate degree."

And the bottom line after food?

Taking Illinois' basic payment of $560.00 as given, attributing 20.00% of your income to child rearing as well, and using the USDA liberal daily child rearing food budget as a benchmark, then:

Your monthly direct basic support spending: $1,120.00
Less your savings on food alone during the child's time with him of $150.61
Less your child support receipts of $560.00
Equals a total financial contribution of: $409.40

His monthly direct base support spending as credited by Illinois: $0.00
Plus his spending on food alone during the child's time with him: $150.61
Plus his child support payments of $560.00
Equals a total financial contribution adjusted for USDA food expenditures of: $710.61

Total child rearing expenditures adjusted for only the transferred expenses of food: $1,270.61, 22.69% of combined net income.

This excludes any additional direct spending costs and savings associated with his parenting time, as well as potential adjustments for child care, education, and more at the discretion of the court.

What are the financial stakes? Under Illinois's default guidelines, whether the split in parenting time is 0 and 365 days or 180 - 185, from a purely budgetary perspective the default formula means a net difference of $1,120.00 base childrearing expenses is at stake.

If your spending is less than $1,120.00?*

It doesn't matter.

You are not accountable for your childrearing expenditures. He is still responsible for a base payment of $560.00 plus other contributions health insurance.

*$1,120.00 is the net difference in base support between what he pays and what you would pay him in basic spending were he the custodial parent.

What if his payments fall behind?

Unlike your spending, he is accountable for his payments. If he falls behind too far, he may lose his drivers license, go to jail or more.

He might go to jail even if you spend less than $1,120.00.

He might go to jail if you spend less on the child even then his monthly payment to you.

Arrears: Past-due Child Support

Illinois charges him interest on arrears, or past-due child support payments.

In Illinois, interest is calculated at an annual rate of 9%. As a benchmark, 10-year US treasuries are running around 2% as of early 2013, and mortgage interest is running under 4%.

Tell me more.


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Support Studies comments on the math, financial and economic aspects of child support formulas and does not give legal advice. Divorced parents are encouraged to contact us through their lawyer.
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