Child support in Illinois is calculated under an Income Shares model, which means that child support is based on both parent’s incomes.  Additionally, if a parent has the minor child or children for at least 146 overnights in a calendar year, there is a further modification to the amount due to the presumption that the parent already contributes a significant amount of support for the child’s needs.  Child support is paid until a minor child turns 18 or graduates from high school, but in no event does child support extend beyond a child’s 19th birthday.  Child support is intended to provide for the “reasonable and necessary physical, mental and emotional health needs of the child.”

To calculate child support, the State of Illinois has provided worksheet guidelines to assist parties in calculating the correct amount.  Such worksheets are not often used by private attorneys, however, as they do not take into account several factors such as unique tax implications, variable incomes, and extraordinary circumstances warranting a deviation from the guidelines. The worksheet is accessible on the Illinois Department of Healthcare and Family Services website. Click here for the most recent version as of December 31, 2018:

Online Child Support Calculator


What is considered income? Statutory child support is based on gross income from all sources. This includes, but is not limited to: employment income, rental income, and other sources of income such as disability income.  There are exceptions, however, such as any public aid assistance or child support received for the benefit of another child. These types of income are not used in calculating one’s child support obligation.

How can I adjust my child support? For example, what if my income changes due to employment changes? Child support is always modifiable provided that the petitioning party can show that there has been a substantial change in circumstances. Courts have interpreted a “substantial change” to typically be an income change of at least 10%.  There are other non-financial factors that may warrant a modification of child support, including the child spending more overnights with the other parent or a change in designation of the child’s custodian or arrangements for payment  of other expenses not previously considered.

Does child support cover everything like private school tuition, uniforms, or extracurricular expenses? In its discretion, the court may order parents to contribute to these expenses in addition to the basic child support obligation.  Said expenses must be intended to enhance the “educational, athletic, social, or cultural development of the child.”

Are daycare or after school care costs included in child support? Parents are responsible for making these payments on top of any child support obligation. Any parent paying for daycare or childcare expenses will receive a credit for these payments, however, which would be reflected in the final child support calculation.

Are there any other instances, aside from the child’s age, when child support would terminate? Yes, child support can be terminated in other situations. Child support may be terminated if a child becomes emancipated by getting married, joining the military, or obtaining employment that provides adequate financial resources for the child, or alternatively, moves out of the home to support his or her self.

What if my child support order was entered under the old law? The that child support laws changed in 2017 is not alone a valid basis to warrant a modification of child support. When the new law was enacted, the Illinois Legislature anticipated that this language was necessary, so as to avoid clogging the courts with reviews of potentially every child support order. If a petitioning party can still prove there has been a substantial change in circumstances, however, the adjusted amount will be calculated under the income shares guidelines.

It is important to speak with an experienced child support attorney to determine what child support issues you may have.  Like most areas of the law, there are individual situations that may warrant a detailed assessment. Procedures to modify child support, terminate it, or adjust arrearages, for example, are not easy to navigate without the help of an experienced child support lawyer in Chicago and the surrounding areas.