When you and your partner have children together, you both have an obligation to support them financially, regardless of whether you were ever married. Therefore, if you separate or divorce, you’re likely going to wonder, “How much is child support in Illinois?”
It’s a simple enough question, but the answer isn’t as straightforward. In this guide, we’ll explain how monthly child support payments are calculated in Illinois and answer frequently asked questions about child support guidelines, order modification, how payments affect your taxes, and the penalties for nonpayment. If you have additional questions, we invite you to schedule a consultation with a Chicago child support attorney at STG Divorce Law.
A note from Raif: Child support is one of the most contentious issues in divorce, but it’s also one of the most formulaic. Illinois changed to the income shares model in 2017, which is fairer but more complex. Here’s what I tell every parent walking into our office: the formula will be the formula, but how we present income, parenting time, and add-on expenses can move the number significantly in either direction.
What Is Child Support Used For?
Child support is intended to help pay for a child’s daily needs. This includes food, clothing, housing, transportation, and basic school-related expenses. It may also contribute to the general household costs that allow the child to live in a safe and stable environment.
In Illinois, both parents are usually required to share certain additional expenses. These costs include work-related daycare, health insurance premiums, and out-of-pocket medical costs. The court divides these expenses based on each parent’s share of the combined net income.
Although child support must be used to meet the child’s needs, the court doesn’t require the receiving parent to track or report how the money is spent. Unless there’s clear evidence of misuse, the court assumes the funds benefit the child. This applies even if the money is used for shared household expenses rather than specific items for the child.
How is the Amount of Child Support Determined?
In Illinois, child support is based on the combined parental income. Before July 1, 2017, Illinois used a percentage-based model where the non-custodial parent paid a set percentage of their net income. For child support orders entered after that date, the state applies an income shares model (a system used by most other states), which considers both parents’ incomes and allocates support based on their combined financial responsibility.
When doing a support calculation, the court uses guidelines set out in the Illinois Marriage and Dissolution of Marriage Act, which include an Income Shares Schedule. These child support guidelines, which estimate typical child-rearing expenses for families at similar income levels, don’t automatically account for discretionary costs like private school, extracurricular activities, or vacations unless the court orders them separately.
The Benefits of the Income Shares Model
Under the income shares model for calculating child support obligations, both parents are responsible for contributing to the child’s needs. The goal is to estimate the amount of support the child would have received if the parents had remained in the same household, using their combined net income as a basis.
This method helps Illinois courts divide child support obligations in a way that reflects each parent’s ability to contribute financially. The goal is always to establish a child support order that’s fair to both parents while keeping the best interests of the child or children at the forefront.
Determining Net Income
The first step in calculating support under the income shares model is for the court to determine the monthly net income of both parents. To help standardize calculations, courts often rely on a gross-to-net income conversion chart provided by the state. While this chart is commonly used, courts may also perform individualized net income calculations when needed, especially for self-employed parents or those with complex financial situations.
Published by the Illinois Department of Healthcare and Family Services, the table shows gross monthly income ranges alongside net income figures. It uses standardized tax amounts (a fixed deduction reflecting federal, state, Social Security, and Medicare taxes) rather than requiring each parent to provide individualized tax calculations.
If you’re trying to prepare, you can use the Illinois Child Support Calculator to get a general idea of what your basic child support obligation might be. Here’s how it works:
- Start with gross income before taxes. For example, Parent A earns $5,000 per month and Parent B earns $3,000 per month.
- Use Illinois’s gross-to-net chart to find standardized net income. In this example, Parent A’s net is $4,000 and Parent B’s net is $2,400.
- Add net incomes together. Combined net income is $6,400 in our sample family.
- Refer to the income shares schedule based on $6,400 combined net and one child. Suppose the table shows $1,200 as the total monthly obligation.
- Allocate support between parents. Each parent’s share is based on their share of combined net income. Parent A pays 62.5 percent ($750) and Parent B pays 37.5 percent ($450).
Note: The 2025 table is available in PDF format (titled “2025 Gross to Net Income Conversion Table Using Standardized Tax Amounts”). It’s updated annually to reflect current tax standards.
Can You Modify an Existing Child Support Amount?
Child support orders can be updated when you can demonstrate a substantial change in circumstances. For example, the court may allow a new order based on adjustments in income, parenting time, or the child’s ongoing needs. In some cases, the child support obligation may also be reviewed after three years, even without a major event.
Here are some common reasons why child support may be modified in Illinois:
- A Change in Income: If either parent’s income goes up or down, the court may adjust the support amount. This includes job loss, promotions, new employment, or changes in bonuses or commission. A temporary dip in income may not be enough on its own, but a lasting change often justifies a review.
- A Change in Parenting Time: If the number of overnight stays with each parent has changed, the support amount may no longer reflect the time each parent is caring for the child. For example, if a child starts living with the other parent most of the time, that could shift who pays and how much. Even smaller changes in parenting time may affect the court’s calculations.
- A Change in the Child’s Needs: Children grow, and their expenses change. Medical expenses, school costs, therapy, or other ongoing needs may increase or decrease. If the current support doesn’t reflect what the child needs now, it may be time for a change.
If you think the current support order no longer makes sense, you can file a petition to have it reviewed. You’ll need to show the court what’s changed and why the support amount should be updated. The court will then decide if a support modification is appropriate.
Is Child Support Tax Deductible in Illinois?
One of the most common questions parents have during or after a divorce is whether child support affects their taxes. In Illinois, the answer is straightforward: child support is not tax deductible for the parent who pays it, and it is not considered taxable income for the parent who receives it. This rule applies across the United States and is based on federal tax law, not state-specific tax codes.
The IRS treats child support obligations differently from other forms of financial support, such as spousal maintenance. The reasoning is that child support is a legal obligation to support one’s child, not a transfer of income between adults. Since the money is intended to cover the child’s living expenses, such as food, clothing, and housing, it carries no tax benefits or burdens for either parent.
Parents should also be aware that mixing child support with spousal support can create confusion. Only spousal support orders entered before January 1, 2019, are tax-deductible for the payor and taxable for the recipient. Child support has never been deductible or reportable, regardless of when the divorce occurred. For that reason, it’s important to keep each type of support obligation clearly separated in a court order or settlement agreement.
Do You Pay Child Support If Parenting Time is Equal?
Even when parenting time is shared equally, child support may still be ordered. This is because the court still compares the parents’ earnings. If one parent earns more, they may be required to pay support to balance the financial responsibility. This helps ensure the child maintains a similar standard of living in both homes.
The court may also consider other financial factors, like health insurance coverage, child care (daycare), and prior support obligations. If both parents earn nearly the same amount and share time equally, support could be waived or reduced. But that outcome isn’t guaranteed: each case is reviewed based on current circumstances
Parents who want to avoid formal support can sometimes agree to cover child-related expenses in other ways, such as direct payments for educational expenses or activity fees. However, these agreements need court approval to be enforceable. Without a formal order, informal arrangements may lead to disputes later on.
If you’re sharing time and think support should be adjusted, it’s best to get a review through the court. The judge will calculate support based on current income and parenting time, not past orders or private agreements.
When Does Child Support End in Illinois?
In Illinois, child support usually ends when the child turns 18. If the child is still in high school at that time, support continues until they graduate or turn 19, whichever happens first. This rule gives older teens the financial support they need to finish high school without disruption.
In some cases, support may extend beyond high school. The court can order either or both parents to contribute to college expenses, including tuition, housing, books, and other related costs. These contributions don’t follow the same rules as regular child support and are decided separately, usually before the child turns 18.
Support may also last longer if the child has a disability. If the child is physically or mentally disabled and unable to become financially independent, the court may order continued support after age 18. This type of support depends on the child’s needs and the ability of each parent to help.
It’s important to note that child support doesn’t end automatically. A parent who believes the obligation should stop must ask the court to terminate or modify the existing order. Until the court approves a change, the obligation remains in effect, even if the child has turned 18 or finished school.
Are There Penalties for Not Paying Child Support?
Yes. Illinois courts take child support enforcement seriously, and failing to meet your obligation can lead to consequences. The penalties vary depending on the amount owed, the length of time payments have been missed, and the parents’ actions during that period.
When a parent falls behind on child support payments, the court may impose interest on the unpaid amount. In Illinois, child support arrears accrue interest at a rate of 9% per year unless otherwise ordered. This interest continues to build until the full balance is paid, even if the child is no longer a minor.
One of the most common enforcement tools is wage garnishment. The Illinois Department of Healthcare and Family Services can work with employers to withhold child support directly from a non-custodial parent’s paycheck. Income withholding may be done without a court hearing and remains in place until the overdue balance is resolved.
In addition to garnishing wages, the state may:
- Intercept tax refunds;
- Freeze bank accounts, or;
- Place liens on personal property.
These actions are intended to recover past-due support and can happen without warning once a case enters enforcement. If the arrears grow large enough, the parents’ credit rating may also be affected.
License suspension is another powerful tool the state uses to compel payment. A delinquent parent’s driver’s license, professional license, or even passport can be suspended if the balance remains unpaid. In more severe cases, the judge may find the parent in contempt of court. This happens when the parent has the ability to pay but chooses not to. Contempt findings can lead to fines, court costs, and even jail time until the parent complies with the order or makes a good faith payment.
The most serious child support violations may lead to criminal charges. If a parent owes more than $5,000 or is more than six months behind, they may be charged with a Class A misdemeanor. If the arrears exceed $10,000 and the parent has left the state to avoid payment, they could face a Class 4 felony charge with possible prison time and fines.
If you’re struggling to keep up with your support obligation, the best thing you can do is request a review of your order and file for a formal modification. Letting the debt grow unchecked will make it harder to manage later and may lead to consequences that affect your job, housing, or freedom. Illinois courts expect parents to meet their support obligations, and enforcement is consistent and long-reaching.
Contact STG Divorce Law for Help With Child Support in Illinois
Child support doesn’t last forever, but the exact end date can depend on school status, disability, or court-approved extensions. It’s important to understand how the law applies in your situation so you’re not caught off guard. If you’re unsure about your current order, it may be time to ask the court for clarification or an update.
At STG Divorce Law, we help parents stay on track with child support obligations and make sure orders reflect current circumstances. To speak with an attorney about ending or modifying support, call our law firm at (630) 216-7544 to schedule a consultation.