Illinois child support is calculated using the Income Shares model under 750 ILCS 5/505, which combines both parents' net incomes and allocates support based on each parent's proportional share. The basic child support obligation for one child in Illinois starts at approximately $1,215 per month, though actual amounts range from $40 per month for low-income parents to over $3,000 monthly for high-earning families. Courts determine how much is child support in Illinois by referencing the Schedule of Basic Child Support Obligations, updated annually, with the most recent revision effective March 5, 2025.
Key Facts: Illinois Child Support
| Factor | Illinois Requirement |
|---|---|
| Calculation Model | Income Shares (both parents' income) |
| Governing Statute | 750 ILCS 5/505 |
| Base Amount (1 child) | $1,215/month starting point |
| Minimum Payment | $40/month per child (low income) |
| Shared Parenting Threshold | 146 overnights (40%) per year |
| Modification Standard | 20% change in income or $50/month |
| Termination Age | 18 years (or 19 if still in high school) |
| College Support | Available through age 23 (25 max) |
| Annual Schedule Update | March 2025 (next review 2026) |
How Illinois Calculates Child Support Amounts
Illinois courts determine child support by combining both parents' monthly net incomes and applying the Schedule of Basic Child Support Obligations to find the total support amount based on the number of children. Each parent then pays their proportional share of that obligation based on their percentage of combined income. For example, if parents have a combined monthly net income of $7,200 with one child, the basic support obligation is $1,324 per month, and if one parent earns 60% of the combined income, that parent pays $794 monthly.
The Income Shares model replaced Illinois' previous percentage-based system on July 1, 2017, following Public Act 99-0764. This approach reflects the economic principle that children should receive the same proportion of parental income they would have received if their parents lived together. The Illinois Department of Healthcare and Family Services maintains the official Child Support Estimator at hfs.illinois.gov, which uses the current schedule updated March 5, 2025.
Net Income Calculation
Net income for child support purposes equals gross income minus specific deductions permitted under Illinois law. Gross income includes wages, salaries, bonuses, commissions, self-employment income, investment returns, rental income, Social Security benefits, workers' compensation, unemployment benefits, pensions, annuities, and most other income sources. Permitted deductions include federal and state income taxes, Social Security taxes (FICA), mandatory retirement contributions, union dues, and health insurance premiums paid for dependents.
The Schedule of Basic Child Support Obligations provides specific monthly support amounts for combined net incomes ranging from under $1,200 to over $30,000 monthly. For combined net incomes between $7,175 and $7,224 with one child, the basic obligation is $1,324 per month. For combined net incomes between $7,175 and $7,224 with two children, the basic obligation is $1,969 per month. These amounts increase with higher combined incomes and additional children.
Illinois Child Support Amount Examples
Understanding how much child support costs in Illinois requires examining real calculation scenarios based on the 2025 Schedule of Basic Obligations. The following examples demonstrate how courts apply the Income Shares formula to determine actual payment amounts.
Example 1: Standard Calculation
Parent A earns $5,000 net monthly income (62.5% of combined). Parent B earns $3,000 net monthly income (37.5% of combined). Combined net income totals $8,000 monthly. For one child, the Schedule shows a basic obligation of approximately $1,400 per month. Parent A pays 62.5% of $1,400, which equals $875 monthly. Parent B pays 37.5% of $1,400, which equals $525 monthly, but if Parent B is the custodial parent, no cash payment changes hands for that share.
Example 2: Low-Income Parent
When a parent's income falls below 75% of the Federal Poverty Guidelines, Illinois law establishes minimum payment floors to protect extremely low-income obligors while still ensuring children receive some support. The minimum child support payment is $40 per month per child, with a maximum of $120 per month regardless of the number of children. For combined incomes under $1,200 monthly, courts may set nominal support amounts between $10 and $50 per month.
Example 3: High-Income Calculation
For parents with combined monthly net incomes of $10,000 and two children, the basic support obligation is approximately $2,068 per month under the 2025 Schedule. If Parent A earns $7,000 (70%) and Parent B earns $3,000 (30%), Parent A's share would be $1,448 monthly. Parent B's share would be $620 monthly, credited against their obligation through providing primary care.
| Combined Monthly Net Income | 1 Child | 2 Children | 3 Children |
|---|---|---|---|
| $4,000 | $820 | $1,220 | $1,440 |
| $6,000 | $1,135 | $1,690 | $1,995 |
| $8,000 | $1,400 | $2,085 | $2,460 |
| $10,000 | $1,600 | $2,380 | $2,810 |
| $15,000 | $2,100 | $3,125 | $3,690 |
Shared Parenting and the 146-Overnight Threshold
Illinois applies a different calculation formula when each parent exercises at least 146 overnights per year with the child, representing 40% of annual parenting time. This shared parenting calculation multiplies the basic support obligation by 1.5 to account for duplicate household expenses such as housing, utilities, food, and transportation that both parents incur when maintaining full residences for the child.
Under the shared parenting formula, each parent's adjusted obligation is calculated by multiplying their share of the basic obligation by the other parent's percentage of parenting time. The parent with the higher resulting obligation pays the difference to the other parent. For example, if the multiplied basic obligation totals $2,100, Parent A has 55% parenting time and earns 60% of combined income, while Parent B has 45% parenting time and earns 40% of combined income, the offset calculation determines who pays whom and how much.
Pending legislation (SB 3524) proposes reducing the shared parenting threshold from 146 overnights to 110 overnights per year, which would significantly affect support calculations for parents with substantial but not equal parenting time. This bill also introduces the concept of overnight equivalents for parents who have significant daytime parenting periods on separate days.
Additional Child Support Expenses Beyond Basic Obligation
Illinois law under 750 ILCS 5/505(a)(2.5) authorizes courts to allocate additional expenses beyond the basic child support obligation. These expenses are typically divided between parents in proportion to their income shares, adding to the total monthly support amount.
Healthcare Expenses
Illinois child support orders must address health insurance coverage for children. Courts typically require the parent with access to employer-provided coverage at reasonable cost to maintain insurance for the children. Unreimbursed medical expenses, including copays, deductibles, prescription costs, dental work, orthodontia, vision care, and therapy, are divided between parents based on their income percentages. The average monthly cost for adding a child to employer health insurance ranges from $150 to $400 per month.
Childcare Expenses
Work-related childcare costs necessary for a parent to maintain employment or attend school are added to the basic support obligation. These expenses include daycare, before-school and after-school programs, summer camps when school is not in session, and registration fees for childcare programs. Illinois childcare costs average $1,200 to $1,800 per month for full-time care in metropolitan areas like Chicago, with lower costs in rural counties. These costs are divided proportionally based on each parent's share of combined income.
Extracurricular Activities
Courts may allocate costs for extracurricular activities, including sports registration fees, equipment, uniforms, music lessons, tutoring, and educational enrichment programs. While not automatically included in every support order, judges consider the children's established interests and the parents' ability to pay when allocating these expenses.
Modifying Illinois Child Support Orders
Illinois permits modification of existing child support orders when circumstances change substantially, defined by statute as at least a 20% variance between the current order and the guideline amount or $50 per month, whichever is less. Either parent may petition for modification at any time, though orders can be formally reviewed every three years through the Illinois Department of Healthcare and Family Services.
Under 750 ILCS 5/510, courts require proof that recalculating support under current circumstances would result in at least a 20% difference from the existing order amount. Involuntary job loss, significant income reduction, disability, remarriage affecting household expenses, changes in parenting time, or changes in the child's needs may constitute grounds for modification. Courts will not reduce support based on voluntary unemployment or underemployment, as judges consider earning capacity rather than actual income when a parent voluntarily reduces their earnings.
The modification takes effect only after a court enters a new order. Parents cannot unilaterally reduce payments based on changed circumstances. Child support arrears continue to accrue at the original order amount until the court formally modifies the obligation, and Illinois charges 9% annual interest on unpaid support balances.
Illinois Child Support Enforcement and Penalties
Illinois employs aggressive enforcement mechanisms to collect unpaid child support, with consequences escalating from administrative actions to criminal prosecution. Every Illinois support order since 1997 includes automatic income withholding, requiring employers to deduct support directly from paychecks before the obligor receives wages.
Income Withholding
Employers must withhold child support within 14 days of receiving a withholding order, facing potential penalties of $100 per day for noncompliance. Illinois law permits garnishment of up to 50% of disposable income for child support when the obligor supports other dependents, or up to 60% when they do not. For obligors with arrears exceeding 12 weeks, an additional 5% may be withheld.
License Suspensions
When arrears reach $500 and payments are 90 days overdue, Illinois can suspend the obligor's driver's license, professional licenses (including medical, legal, and real estate licenses), and recreational licenses. Suspension continues until the court determines the obligor has resumed compliance with the support order.
Tax Intercepts and Liens
The Illinois Department of Healthcare and Family Services intercepts federal and state tax refunds, stimulus payments, Social Security benefits, and unemployment compensation to satisfy child support arrears. Each missed payment automatically becomes a judgment against the obligor, creating liens against real property that can be enforced through foreclosure-style proceedings.
Contempt of Court and Criminal Penalties
Courts may hold non-paying parents in civil contempt, imposing fines and jail time until compliance. Criminal non-support becomes a Class 4 felony when arrears exceed $10,000, carrying penalties of up to 6 months in jail and fines up to $25,000. Fleeing the state to avoid child support obligations triggers federal prosecution under the Deadbeat Parents Punishment Act.
Child Support for College Education in Illinois
Illinois is one of the minority of states where courts can order parents to contribute to college education expenses without an agreement between the parties. Under 750 ILCS 5/513, courts may require contribution to post-secondary educational expenses through age 23, with extensions to age 25 in exceptional circumstances.
College expense orders typically cover tuition, books, room and board, student fees, living expenses, utilities, and transportation. Courts use the cost of attendance at the University of Illinois at Urbana-Champaign as a benchmark, approximately $35,000 to $40,000 annually for Illinois residents, unless the petitioner demonstrates good cause for higher expenses at a different institution.
Support for college expenses terminates upon the student's failure to maintain a C average, marriage, or graduation, whichever occurs first. The recent DuPage County case Yakich v. Auld challenged the constitutionality of mandatory college contribution orders, and the case is currently on appeal to the Illinois Supreme Court, potentially affecting future college support obligations.
Illinois Divorce Filing Fees and Court Costs
While child support orders can exist independently of divorce, parents frequently establish support during dissolution proceedings. Filing fees vary by county, with Cook County charging $388 for the initial divorce petition, the highest rate in Illinois. DuPage County charges $348, while smaller counties like Stephenson County charge approximately $306.
As of March 2026, verify all fees with your local circuit clerk before filing, as amounts change periodically.
Illinois offers fee waivers for parents unable to afford court costs. Under Illinois Supreme Court Rule 298, households with income at or below 125% of the federal poverty guidelines qualify for waivers. For a single person in 2026, this threshold is approximately $18,500 annually. Applicants submit an Application for Waiver of Court Fees demonstrating financial hardship.
Frequently Asked Questions
How much is child support for one child in Illinois?
Child support for one child in Illinois starts at a base amount of $1,215 per month, adjusted based on both parents' combined net income. At combined monthly incomes of $8,000, the basic obligation is approximately $1,400 monthly. Courts divide this amount proportionally based on each parent's percentage of combined income, with the non-custodial parent typically paying their share directly.
What is the average child support payment in Illinois?
The average child support payment in Illinois ranges from $800 to $1,500 monthly for one child, depending on parents' incomes and parenting time arrangements. For combined net incomes of $10,000 per month with two children, the basic obligation is approximately $2,380 monthly. Low-income parents pay minimums starting at $40 per child per month.
How do Illinois courts calculate child support amounts?
Illinois courts calculate child support using the Income Shares model under 750 ILCS 5/505. Both parents' monthly net incomes are combined, and the Schedule of Basic Child Support Obligations determines the total support amount. Each parent's share is calculated based on their percentage of combined income, with the non-custodial parent paying their portion to the custodial parent.
Can child support be modified if my income changes?
Child support can be modified when the recalculated amount differs by at least 20% from the existing order or $50 per month, whichever is less. Either parent can petition for modification based on involuntary job loss, significant income changes, disability, or changed custody arrangements. Voluntary income reduction does not qualify for reduced support obligations.
What happens if I don't pay child support in Illinois?
Non-payment of child support in Illinois triggers wage garnishment up to 50-60% of disposable income, driver's license suspension, professional license suspension, tax refund interception, property liens, and potential jail time for contempt. Arrears exceeding $10,000 constitute a Class 4 felony with penalties including 6 months imprisonment and $25,000 fines.
Does child support cover college expenses in Illinois?
Illinois courts can order parents to contribute to college expenses through age 23, with possible extensions to age 25. Orders typically cover tuition, books, room and board, and living expenses, benchmarked against University of Illinois costs (approximately $35,000-$40,000 annually). Support terminates if the student fails to maintain a C average or gets married.
How does shared parenting affect child support in Illinois?
When each parent has at least 146 overnights (40%) annually, Illinois applies a shared parenting formula that multiplies the basic obligation by 1.5 to account for duplicate household expenses. Each parent's adjusted share is offset against the other, with the higher-obligation parent paying the difference. This typically reduces the payment compared to standard custody arrangements.
What income counts toward child support in Illinois?
Illinois considers virtually all income for child support calculations, including wages, salaries, bonuses, commissions, self-employment income, investment returns, rental income, Social Security benefits, pensions, annuities, workers' compensation, and unemployment benefits. Net income equals gross income minus taxes, FICA, mandatory retirement contributions, union dues, and dependent health insurance premiums.
How long does child support last in Illinois?
Child support in Illinois continues until the child turns 18, or 19 if still attending high school. Support terminates at age 19 regardless of high school completion status. Courts may order contribution to college expenses through age 23, with extensions to 25 in exceptional circumstances. Marriage or emancipation also terminates support obligations.
Where can I estimate my Illinois child support payment?
The Illinois Department of Healthcare and Family Services provides an official Child Support Estimator at hfs.illinois.gov using the current Schedule of Basic Obligations (updated March 2025). The calculator offers both a question-and-answer format for parents and a direct-entry worksheet for legal professionals. Results provide estimates only; actual court orders may differ based on case-specific factors.