Posted on September 1, 2017

How Do I Calculate Child Support In Chicago, Illinois?

“Both parents have the financial responsibility to support a minor child.” In re Marriage of MacZko, 263 Ill. App. 3d 991, 994 (Ill. App. Ct. 1992)

Effective July 1, 2017, courts in the State of Illinois implemented changes to how child support is to be calculated. Going forward, child support obligations will be calculated using something called the “Income Shares Method”. The formula no longer uses a straight percentage to calculate income. Instead, it calculates child support incorporating both the non-custodial and the custodial parent’s income.

  1. Standardized Net Income

To calculate child support under the new law, the courts now ask that both parents disclose their gross monthly incomes by completing a Financial Affidavit and supplying copies of recent paystubs. After these initial disclosures are made, the gross income amounts are converted into “Standardized Net Income” amounts, determined by a standardized chart published by the Illinois Department of Health and Family Services. You can view a copy of this chart online at , or by performing an internet search for “Standardized Net Income Chart Illinois”.

  1. Combined Net Income

These standardized net amounts for both parents are added together to calculate what the courts refer to as the parents’ “Combined Net Income”. This figure represents both parents’ total combined income.

  1. Income Shares Table

The next step is to refer to another document published by the Illinois Department of Health and Family Services titled “Income Shares Schedule”. We take the Combined Net Income calculated in step two above, and correspond it accordingly with the appropriate figure on the chart. This will later be used to determine the final amount the payor will owe. This dollar figure reflects the total child support amount that the parties will need to contribute together for the minor child. You can view this chart at, or by performing an internet search for “Combined Net Income Chart Illinois”.

  1. Percentage

Calculate the percentage of the total Combined Net Income each party earns. So, for example, if the Petitioner earns $75,000.00 a year and the Respondent earns $25,000.00 a year, than the Petitioner would earn 75% of the Combined Net Income, and the Respondent would earn 25% of the Combined Net Income.

  1. Calculating the Final Amount of Child Support Owed and Payable

The final step is to take the amount determined from the Income Shares Table in step three, and the Payor’s percentage of the Combined Net Income calculated in step four. The obligor shall pay the percentage of the total income from the Income Shares Table equal to his percentage contribution to the parties’ Combined Net Income. So, for example, the Petitioner from step four who earns 75% of the Combined Net would be expected to pay 75% of the total from the  Income Shares Table. This would be his child support amount. The Obligee shall not pay herself any child support (obviously).

CAVEAT: Please note this is a general calculation for cases where there is no shared parenting time and both parties are simply W-2 wage earners. Your specific situation may require additional calculations or different considerations. For example, if you have 50/50 custody, child support is calculated differently.

Most lawyers just use the online calculator to estimate the child support but your attorney should always take the formal steps to calculate child support as listed above.

The child support calculation is not the last step.  The child’s expenses and any possible child support arrearages must also be calculated but those are done in a less mathematical manner.

There are still many factors like what happens to a bonus or other surprise income (or losses of income).  Contact my Chicago, Illinois law office to learn more about how much child support you will be paying or receiving.

If you’d like to read this article in Spanish, click here.

Share Article on


Russell Knight

Russell D. Knight has been practicing family law as a Chicago divorce lawyer since 2006. Russell D. Knight amicably resolves tough cases while remaining a strong advocate for his client’s interests.

More about This Topic

Relevant Articles

Call Now Button