Illinois Child Support Statute: Calculation and Enforcement

Illinois child support law requires both parents to contribute financially to raising their children, using an income shares formula that combines both parents’ net incomes and splits the child’s estimated costs in proportion to what each earns. The main statute is 750 ILCS 5/505, part of the Illinois Marriage and Dissolution of Marriage Act, and it applies whether the parents were married, divorced, or never together.

How the Amount Is Calculated

Illinois switched to the income shares model on July 1, 2017, replacing an older approach that looked only at the non-custodial parent’s income.¹ The idea behind the change is simple. Estimate what the parents would have spent on the child had they stayed under one roof, then divide that number by each parent’s share of their combined net income.

The state publishes economic tables setting basic child-rearing costs at different combined income levels. The court finds the “basic child support obligation” on those tables, then assigns each parent a proportional share. A parent who earns 60% of the combined income owes 60% of the obligation.²

Parenting time changes the math. When the non-custodial parent has 146 or more overnights per year, the basic obligation is multiplied by 1.5, and each parent’s share is recalculated to reflect direct spending in both households.² This shared-care adjustment keeps the child’s standard of living roughly consistent between homes.

A judge can deviate from the guideline amount when strict application would be unfair — extraordinary medical costs, unusual educational needs, or a wide gap in the parents’ financial situations. Any deviation must be explained in writing, and the order must state what the guideline amount would have been.²

What Counts as Income

Gross income is defined broadly. It includes wages, bonuses, self-employment earnings, rental income, dividends, pensions, Social Security benefits, and workers’ compensation. Spousal maintenance received under a court order also counts as the recipient’s income.²

Means-tested public assistance is not counted. TANF, SSI, and SNAP benefits stay out of the calculation, as do benefits a parent receives for other children in the household, such as foster care payments or survivor benefits.²

Self-employed parents face extra scrutiny; only legitimate business expenses reduce reported income. If a parent is voluntarily unemployed or underemployed to shrink support, the court can impute income based on that parent’s education, work history, and realistic earning capacity. Irregular income like bonuses or commissions is typically averaged over a reasonable period so the support amount stays stable.

Social Security Disability

SSDI benefits count as part of the recipient parent’s gross income. If the child also receives dependent benefits from the disabled parent’s earnings record, the paying parent gets a dollar-for-dollar credit against the support obligation. A parent owing $500 whose child receives $300 in SSDI dependent benefits pays the remaining $200.²

Low-Income Minimums

For a parent whose gross income is at or below 75% of the federal poverty guidelines for a single person, the presumptive minimum order is $40 per month per child, capped at $120 per month across all children. Because the $40 floor is only a rebuttable presumption, a judge can set it aside — issuing a zero-dollar order — for a parent with no income at all, one who receives only means-tested assistance, or one who cannot work because of a documented disability, incarceration, or institutionalization.²

Health Insurance and Other Add-Ons

Child support orders routinely require one parent to carry health insurance for the child if employer- or union-sponsored coverage is available, with premiums withheld from that parent’s paycheck. The insurance cost cannot exceed 5% of the providing parent’s gross income. A parent whose net income falls below 133% of the federal poverty guidelines, or whose child already has Medicaid, generally cannot be ordered to pay for private coverage unless it is available at no cost.²

Courts can also allocate childcare, educational expenses, and extracurricular fees between the parents. Those additions sit on top of the guideline amount.

Starting a Case

A parent files a petition in the circuit court where the child lives. Either parent can file, and if the family receives public assistance the Department of Healthcare and Family Services (HFS) can open the case on the custodial parent’s behalf.³ Parentage must be established first, whether by voluntary acknowledgment, genetic testing, or a judicial finding.

Both parents disclose their finances. The court reviews pay stubs, tax returns, and business records, and can subpoena employment or financial records if a parent won’t cooperate. Payments flow through the Illinois State Disbursement Unit (SDU), which processes checks, direct deposits, and debit card payments to the receiving parent and creates the official payment record that becomes critical in any later enforcement dispute.⁴

Enforcement When a Parent Doesn’t Pay

Illinois has stacked enforcement tools that escalate with the size and age of the delinquency.

Income Withholding

Every support order in Illinois includes an income withholding provision. Employers deduct support from the parent’s paycheck and send it to the SDU, applying withheld funds first to current support, then to health insurance premiums, then to past-due balances.⁵ Employers that ignore a withholding notice face penalties.

Liens and Intercepts

Overdue support automatically creates a lien against the parent’s real estate and personal property, so a parent in arrears cannot sell a home or refinance without addressing the debt.² The state can also intercept federal and state tax refunds, lottery winnings, and other government payments.⁶

License Suspension

Under the Non-Support Punishment Act, a court can suspend a delinquent parent’s driver’s license once support has been unpaid for 90 days or more, though a restricted permit for work and medical appointments is possible.⁷ HFS can also administratively pursue revocation or denial of professional, occupational, and recreational licenses, which for parents in licensed trades or professions is often the tool that produces payment fastest.

Passport Denial

Federal law makes a parent who owes $2,500 or more in child support arrears ineligible for a U.S. passport. State child support agencies certify delinquent cases to the federal Office of Child Support Services, which reports them to the State Department.⁸ The passport block stays in place until the arrears are resolved.⁹

Credit Reporting and Contempt

Delinquent accounts get reported to consumer credit agencies and can stay on a credit report for up to seven years, affecting borrowing, housing applications, and sometimes employment. A parent who disobeys a support order can also be held in civil contempt, with penalties including probation and periodic imprisonment of up to six months, though the court can allow work release during the day.² Because contempt is meant to compel compliance rather than punish, a parent who resumes paying can often get the jail time lifted.

Criminal Charges

Willful non-payment can also be prosecuted under the Non-Support Punishment Act. A first offense is a Class A misdemeanor when the obligation has gone unpaid more than six months or arrears exceed $5,000. It becomes a Class 4 felony when the parent leaves the state to dodge support and arrears exceed $10,000, when non-payment continues more than a year, when arrears exceed $20,000, or when there is a prior non-support conviction. A Class A misdemeanor carries up to one year in county jail; a Class 4 felony carries one to three years in state prison.¹⁰ Conviction requires proof that the parent had the ability to pay and chose not to.

Changing an Order

Support orders can be modified when circumstances change. A parent files a petition and shows a “substantial change in circumstances” since the last order — a major income shift, job loss, disability, or a significant change in the child’s needs.¹¹

For cases handled through HFS, there’s a second path. Every 36 months HFS can review an order without requiring proof of a substantial change, and modify it if the current amount differs from the guideline by at least 20% and at least $10 per month.¹¹

One rule catches many parents off guard. Modifications only affect future payments. A court cannot retroactively reduce support that was already due before the modification petition was filed. A parent who waits months to file after losing a job still owes the full original amount for every month of that delay, so filing promptly matters.

When Support Ends

Child support continues until the child turns 18, or until high school graduation, whichever comes later. If the child is still in high school at 18, payments continue until graduation or the child’s 19th birthday, whichever comes first.²

Termination is not automatic. The paying parent has to file a motion to formally end the obligation, and any unpaid balance survives. Arrears continue to be collectable through every enforcement tool listed above. Support can end early if the child marries, joins the military, or is otherwise legally emancipated.

College and Disabled Adult Children

Illinois is one of the states that can require parents to contribute to a child’s college costs after 18. Under 750 ILCS 5/513, courts weigh both parents’ resources, the child’s academic performance, and the school’s cost. Expenses must generally be incurred before the student turns 23, with an extension to 25 possible for good cause, and the obligation ends if the child fails to maintain a C average, earns a bachelor’s degree, or marries.¹²

For an adult child whose disability prevents self-sufficiency, support can be extended beyond the usual age limits under 750 ILCS 5/513.5, and the right to petition survives the parent’s death, allowing a claim against the estate.¹³

Two Boundaries Worth Knowing

If one parent moves out of state, the Illinois order is still enforceable. Illinois has adopted the Uniform Interstate Family Support Act at 750 ILCS 22, which follows a “one order at a time” rule: only one state holds continuing, exclusive jurisdiction, so conflicting orders can’t stack up.¹⁴ The custodial parent can register the Illinois order in the other state for enforcement using that state’s collection tools.

Bankruptcy does not erase child support. Federal law classifies it as a “domestic support obligation,” which is excepted from discharge in both Chapter 7 and Chapter 13.¹⁵ The automatic stay that pauses most creditor collection during bankruptcy does not apply to child support enforcement, so wage withholding and other collection efforts continue while the case is pending.

1
Illinois Department of Healthcare and Family Services. Income Shares
2
Illinois General Assembly. Illinois Code 750 ILCS 5/505 – Child Support; Contempt; Penalties
3
Illinois Department of Healthcare and Family Services. Child Support Frequently Asked Questions – Parents
4
Illinois State Disbursement Unit. Illinois State Disbursement Unit
5
Justia Law. Illinois Code 750 ILCS 28 – Income Withholding for Support Act
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Illinois General Assembly. Illinois Code 305 ILCS 5/10-17.6
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Illinois General Assembly. Illinois Code 750 ILCS 16 – Non-Support Punishment Act
8
U.S. Department of State. Pay Child Support Before Applying for a Passport
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Administration for Children and Families. Overview of the Passport Denial Program
10
Illinois General Assembly. Illinois Code 750 ILCS 16/15 – Failure to Support
11
Illinois General Assembly. Illinois Code 750 ILCS 5/510
12
Illinois General Assembly. Illinois Code 750 ILCS 5/513 – Educational Expenses for a Non-Minor Child
13
Illinois General Assembly. Illinois Code 750 ILCS 5/513.5
14
Illinois General Assembly. Illinois Code 750 ILCS 22 – Uniform Interstate Family Support Act
15
Office of the Law Revision Counsel. 11 USC 523 – Exceptions to Discharge