What Factors Affect the Amount of Child Support Ordered in Illinois?

 Posted on February 28, 2026 in Child Support

If you are going through a divorce or separation and have children, child support is likely one of your biggest concerns. You may wonder how the court will decide how much to order and whether the amount will be fair. Our Arlington Heights family law attorney can help you understand how Illinois calculates child support and what factors could affect the final number in your case.

How Does Illinois Calculate Child Support?

Illinois used to use a model that looked at only one income per household. Eventually, Illinois lawmakers realized that this was an outdated model and tended to penalize the higher earner in the relationship. In 2026, Illinois uses a method called the Income Shares model to calculate child support. This approach is based on the idea that a child should receive the same amount of financial support that they would have received if the family had stayed together.

Under 750 ILCS 5/505, the court calculates child support by following these steps:

• Determining each parent's monthly net income
• Adding both parents' net incomes together to get a combined monthly net income
• Using the state's Schedule of Basic Child Support Obligations to find the total support amount (based on combined income and the number of children)
• Dividing that total between the parents based on each parent's percentage share of the combined income

Remember that net income is not the same as gross income. It is your total income from all sources – wages, self-employment, rental income, bonuses, and more – minus deductions like federal and state income taxes, Social Security, and Medicare.

Illinois updates its income shares schedule periodically. The figures used in your case will reflect current guidelines.

What Specific Factors Can Affect the Child Support Amount in Illinois?

While the income shares formula is the starting point, several factors can raise or lower the final number.

Each Parent's Income

The most important factor is how much each parent earns. The higher the combined income, the higher the base support obligation. If one parent earns significantly more than the other, they will usually be responsible for a larger share of the total.

If a parent is purposefully unemployed or working less than they could, the court can assign them a "potential income" based on their work history, education, and the local job market.

Parenting Time

How much time each parent spends with the child also affects child support. If both parents have the child for at least 146 overnights per year, Illinois applies a "shared parenting" calculation. The result is usually a lower payment than in cases where one parent has the majority of parenting time.

Equal parenting time does not automatically cut out child support payments for either parent. If there is a large income gap between the parents, the higher-earning parent will usually still owe some support.

Health Insurance Costs

The cost of a child's health insurance is considered in the support obligation. Under 750 ILCS 5/505(a)(4), the actual premium for the child is divided between the parents in proportion to their incomes. Whoever pays the premium will have their child support adjusted to reflect that contribution.

Child Care and Other Add-On Expenses

Work-related child care costs can also be factored into the total support obligation. The court may also order parents to share the cost of a child's extracurricular activities and school expenses.

Special Needs or Unusual Circumstances

If a child has a disability or special medical or educational needs, the court may order more support to make sure those needs are covered.

When Do Illinois Courts Deviate From the Basic Child Support Calculation?

The court may decide to adjust the results of the basic calculation or use a different method of determining child support if it finds that doing so is in the best interests of the children. In making this decision, the court will consider factors like the financial needs of the children and the parents, the children’s expected standard of living in a two-parent household, and the physical, emotional, and educational needs of the children.

The court may also order child support beyond the basic calculation for some of the child’s needs. These could include things like care for a child with special needs, expenses related to education and extracurricular activities, and the cost of child care for a parent who needs it in order to work or pursue an education.

Call an Arlington Heights Child Support Attorney Today

Child support calculations can be complicated, but if you have good legal counsel, it doesn’t have to be a stressful unknown. A Rolling Meadows child support lawyer at the Law Offices of Donald J. Cosley is ready to help.

Attorney Cosley personally handles all aspects of his cases – when you call with questions, you will speak directly with him, not a paralegal or assistant. Call 847-253-3100 today for your free consultation.