How Is Child Support Calculated in Illinois?

 Posted on November 25, 2025 in Child Support

Financial stability for children is a priority when parents split. Illinois courts use a specific formula to make sure both parents contribute to their child’s care. The calculation is based on parental income, parenting time, and the child’s everyday needs. With help from our Oswego, IL child support lawyer, you can better understand what to expect.

What Formula Does Illinois Use to Calculate Child Support?

Under 750 ILCS 5/505, Illinois courts use the income shares model to calculate child support. This formula estimates what both parents would spend on their child if they lived together. Then, it divides that cost between the parents based on how much each one earns.

The court starts by calculating each parent’s net income, then adds the two amounts together. A standard chart from the Illinois Department of Healthcare and Family Services shows how much of that combined income should be used for child support. Each parent is assigned a percentage of that total based on their income.

What Counts as Income for Child Support in Illinois?

Illinois defines income very broadly. It can include wages, salaries, tips, bonuses, commissions, overtime pay, rental income, and benefits such as unemployment or pension payments. It can also include money earned from investments or self-employment.

However, some payments do not count as income. For example, public assistance, Supplemental Security Income (SSI), and child support received for other children are not included. If a parent is not working or is working less by choice, the court can assign an "imputed income." This means the court estimates what that parent could earn based on work history, skills, and education.

How Does Parenting Time Affect Child Support Payments?

Parenting time has a significant impact on how much child support is paid. If one parent has most of the parenting time, the other parent usually pays child support based on their share of income. When both parents share equal or nearly equal time, the court uses a different calculation.

Illinois law defines shared parenting as when each parent has the child at least 146 overnights per year. In these situations, the total child support amount is reduced because both parents are paying for food, housing, and other daily needs while the child is in their care.

What Other Factors Can Affect Child Support Amounts?

The income shares formula is a guideline, but judges can make adjustments if special circumstances exist. The goal is always to meet the child’s best interests and create a fair arrangement. Factors that may influence the final amount include:

• Health insurance and medical costs

• Childcare or school tuition

• Extracurricular activities and lessons

• Support obligations for other children

• Special needs or unusual living expenses

If your financial situation changes, you can ask the court to review the support order. Under 750 ILCS 5/510, you may request a change to child support when there is a "substantial change in circumstances." This could mean a new job, a loss of income, or a major change in parenting time. Courts may also allow a review every three years to make sure the amount still fits the legal guidelines.

Contact Our Plainfield, IL Child Support Attorney for a Free 30-Minute Consult

Attorney Robert F. Kramer is an accomplished trial and appellate lawyer with more than 40 years of experience. He is known for being supportive, guiding clients through every step of their case with compassion. He will listen to your concerns, explain each part of the process, and help you make informed decisions.

Contact The Law Offices of Robert F. Kramer, Ltd. today at 630-785-2400 to schedule your free 30-minute consultation with an experienced Oswego, IL child support lawyer you can trust with something as sensitive as your financial future.