Illinois calculates child support using an income shares model that combines both parents’ net incomes and divides the obligation based on each parent’s percentage of the total.
Key Takeaways:
- Illinois child support is based on both parents’ combined net income and is divided proportionally based on each parent’s earnings.
- Parenting time affects the calculation, with shared custody arrangements using a different formula than primary custody situations.
- Errors in income or parenting time calculations can significantly impact support orders, making experienced legal guidance essential.
When parents divorce or separate, one of the most pressing questions is how much child support will be owed. Illinois uses a specific formula to calculate support, but the final number depends on several factors that can make a significant difference in what you pay or receive.
Understanding how child support works in Illinois helps you plan for your financial future and ensures your children’s needs are met. Here’s what you need to know about how courts determine child support in the state.
Illinois Uses an Income Shares Model
Illinois follows the “income shares” model for calculating child support. This approach is based on the idea that children should receive the same proportion of parental income they would have received if their parents had stayed together.
Under this model, courts look at both parents’ net incomes and combine them to determine the total amount that would typically be spent on raising a child in a household with that income level. The support obligation is then divided between the parents based on each person’s share of the combined income.
For example, if one parent earns 60% of the combined income and the other earns 40%, the higher-earning parent would be responsible for 60% of the child support obligation.
What Counts as Income?
Illinois courts consider a broad range of income sources when calculating child support. This includes salary, wages, commissions, bonuses, and overtime pay. Self-employment income, investment income, dividends, and rental income also count. Courts factor in pension and retirement payments, Social Security benefits, unemployment compensation, and workers’ compensation benefits. Spousal maintenance received from a previous marriage is included as well.
Courts look at gross income first, then allow certain deductions to arrive at net income. Allowable deductions include federal and state income taxes, Social Security contributions, mandatory retirement contributions, union dues, and health insurance premiums for the parent (not the child).
The Role of Parenting Time
Parenting time plays a significant role in child support calculations. Illinois recognizes that the parent who has the children more often incurs more day-to-day expenses, while the parent with less time may owe more in support.
The calculation changes based on the number of overnights each parent has:
Sole or Primary Custody
When one parent has the children for the majority of the time (more than 216 overnights per year), the other parent typically pays child support based on the standard formula.
Shared Parenting (50/50 or Close to It)
When parents share parenting time more equally (each parent has at least 146 overnights per year), Illinois uses a different calculation that accounts for the shared expenses. The formula adjusts to reflect that both parents are directly covering costs during their parenting time.
Even with a 50/50 arrangement, child support may still be owed if there’s a significant income disparity between the parents. The goal is to ensure the children have a similar standard of living in both homes.
Using the Illinois Child Support Guidelines
Illinois provides standardized guidelines that courts use to determine the basic child support obligation. These guidelines are based on economic research about what families typically spend on children at various income levels.
The basic support obligation covers:
- Housing costs
- Food and clothing
- Transportation
- Basic entertainment and activities
- Education expenses (excluding college)
The guidelines produce a base number, but the final support order often includes additional amounts for specific expenses.
Additional Expenses Beyond the Basic Obligation
Child support in Illinois often goes beyond the basic guideline amount. Courts can order parents to share responsibility for additional child-related expenses, including:
Healthcare Costs
Parents typically share the cost of health insurance premiums for the children. They also divide unreimbursed medical expenses, such as copays, deductibles, prescriptions, dental work, vision care, and mental health services. The division usually follows the same income percentage used for basic support.
Childcare Expenses
Work-related childcare costs, such as daycare or after-school programs, are typically added to the basic support obligation and divided between the parents based on their income shares.
Education Expenses
Private school tuition, tutoring, and other educational expenses may be included in the support order if the court finds them appropriate. For divorced parents, Illinois law also allows courts to order contributions to college expenses, which is handled separately from child support.
Extracurricular Activities
Costs for sports, music lessons, summer camps, and other activities can be divided between parents. Courts consider what activities the children participated in during the marriage and what’s reasonable given the family’s financial situation.
When Courts Deviate from the Guidelines
While Illinois courts generally follow the child support guidelines, they have discretion to deviate from the calculated amount when circumstances warrant. Reasons for deviation include extraordinary medical or educational needs of the child, special talents requiring additional investment, the financial resources of both parents, the standard of living the child would have enjoyed if the parents had stayed together, and the physical, emotional, and educational needs of the child.
If you believe the guideline amount doesn’t reflect your situation, you can request a deviation, but you’ll need to provide evidence supporting your request. An attorney can help you determine whether deviation is appropriate for your situation and present the evidence courts need to see.
How Self-Employment Affects Child Support
Calculating child support becomes more complicated when one or both parents are self-employed. Unlike W-2 employees with consistent paychecks, self-employed individuals may have fluctuating income, business expenses, and tax strategies that affect how much income is available for support.
Courts look beyond tax returns to determine actual income. They may examine:
- Business bank statements
- Profit and loss statements
- Accounts receivable
- Personal expenses paid through the business
- Depreciation and other non-cash deductions
Self-employed parents sometimes underreport income or inflate business expenses to reduce their support obligation. If you suspect this is happening, an experienced attorney can help uncover the true financial picture.
How Long Does Child Support Last?
In Illinois, child support typically continues until the child turns 18. However, support extends until age 19 if the child is still completing high school.
Support may also continue or resume for children with disabilities who cannot support themselves. Additionally, as mentioned earlier, Illinois courts can order parents to contribute to college expenses, which is a separate obligation from regular child support.
Modifying Child Support
Child support orders aren’t permanent. Either parent can request a modification if circumstances change substantially. Common reasons for modification include:
- Significant increase or decrease in either parent’s income
- Job loss or involuntary unemployment
- Changes in parenting time arrangements
- Changes in the child’s needs
- Changes in healthcare costs or childcare expenses
To modify support, you’ll need to file a motion with the court and demonstrate that the change in circumstances is significant and ongoing. Because courts scrutinize modification requests carefully, having legal guidance strengthens your case and helps avoid delays.
Enforcing Child Support Orders
When a parent fails to pay child support, Illinois has several enforcement tools available:
- Income withholding (garnishing wages)
- Intercepting tax refunds
- Suspending driver’s licenses, professional licenses, or passports
- Placing liens on property
- Holding the non-paying parent in contempt of court
If your co-parent isn’t paying support as ordered, an attorney can help you pursue the right enforcement tools and collect what’s owed.
Why Accurate Calculations Matter
Child support affects your family’s financial stability for years. An incorrect calculation, whether too high or too low, creates problems for everyone. The paying parent may struggle to meet their own expenses, while the receiving parent may not have enough to cover the children’s needs.
Getting the calculation right from the start requires accurate income information, proper documentation, and a clear understanding of how Illinois law applies to your situation. Small errors in income reporting or parenting time calculations can result in support orders that are hundreds of dollars off each month.
KHK Family Law & Divorce Attorneys
Child support calculations in Illinois involve many variables, and the outcome significantly impacts your financial future and your children’s well-being. Whether you’re seeking support or expecting to pay it, having experienced guidance ensures the calculation reflects your true circumstances.
At KHK Family Law & Divorce Attorneys, we bring over 70 years of combined experience in family law, along with professional training in psychology and business. We take time to understand your financial situation and advocate for arrangements that work for your family.
Book a free consultation today to discuss your child support questions and learn how we can help.
