Illinois has established child support guidelines to ensure that minor children receive financial support from both parents. To calculate a fair amount of child support, the law accounts for the family’s shared custody arrangement and the combined net income of both parents. 

Before facing a child support hearing, parents should learn more about the factors that contribute to the payment determination. 

Support with joint physical custody 

Illinois uses this formula when the child spends at least 146 annual overnights with each parent: 

  • Find the combined gross income of both parents, which includes salary and wages, court-ordered spousal support, and overtime pay. It does not include court-ordered support for a child from another relationship or benefits from public assistance programs. 
  • Use the state income conversion chart to find the net income for each parent and express it as a percentage of total income.  
  • Calculate the percentage of each parent’s contribution to support. For example, if one parent has net income of $6,000 and the other $4,000, they respectively pay 60% and 40% of the cost of raising the child. 
  • Look at the income shares schedule to find the basic child support obligation. In the example above, it would be $1,445 for one child. 
  • Adjust the support percentage by the exact number of overnights each parent will spend with the child. 

Support with sole physical custody 

When one parent has visitation of fewer than 146 overnights a year, he or she pays child support to the parent with primary custody. Unlike the calculation for joint physical custody, the court will not adjust the support amount based on parenting time. 

Other factors 

The judge can deviate from the child support guideline amount if he or she provides reason for the deviation in writing. For example, a child who has a chronic illness will require additional support to cover medical expenses. 

Parents who do not work because of disability or incarceration will not have a legal child support obligation. Individuals who earn at or below 75% of the federal poverty threshold will pay no more than $40 per child per month to a maximum of $120.