How to collect unpaid child support in Illinois
Arrears, interest and enforcement, with a letter to the agency.
Checked against official sources: Oct 25, 2026.
Short answer
Arrears means child support that is past due. By law, support more than 30 days past due carries interest at 9% a year. Since January 1, 2021, CSS no longer calculates or enforces interest unless a court has ordered it, but you may still owe court-ordered interest.
- Interest on unpaid support
- 9% a year
- Passport denial
- Over $2,500 past due (federal law)
How support is collected in Illinois
Arrears means support that is past due. The child support agency can use these tools to collect it:
- Income withholding (including unemployment benefits)
- Federal and state tax refund intercept
- Comptroller offset
- Passport denial or revocation
- Driver's license suspension
- Professional and hunting/fishing license suspension
- Credit bureau reporting
- Liens on bank accounts, real estate, personal property and lawsuit settlements
- Offset of lottery and casino winnings
Law: 750 ILCS 5/505
Ask the agency in writing to collect what is owed: Ask the agency to collect unpaid support
Interest on arrears in Illinois
By law, support more than 30 days past due carries interest at 9% a year. Since January 1, 2021, CSS no longer calculates or enforces interest unless a court has ordered it, but you may still owe court-ordered interest. At the end of a case, you can ask HFS in writing to have interest adjudicated.
Law: 0.75% a month; 89 Ill. Adm. Code 160.89
Source: HFS FAQ
Federal collection tools
- Tax refunds. The federal government can take a federal tax refund to pay past-due child support. Law: 42 U.S.C. 664
- Passports. A parent who owes more than $2,500 in past-due support can be refused a passport. Law: 42 U.S.C. 652(k)
- Pay withholding limit. For support, up to 50% of take-home pay can be withheld if the parent supports another spouse or child, or 60% if not. It is 55% or 65% when support is more than 12 weeks behind. Law: 15 U.S.C. 1673(b)
- Past-due support. Each unpaid payment becomes a judgment on the day it is due. It can't be lowered later, except back to the date the other parent got notice of a request to change the order. Law: 42 U.S.C. 666(a)(9)
Court action in Illinois
CSS does not jail parents for not paying, but a judge can order jail after finding a parent in contempt for not following a support order.
Source: HFS FAQ
In nearby states
Your next steps in Illinois
Keep a payment record
Keep a log of every payment and every missed payment.
Ask the agency to enforce
Contact Illinois Department of Healthcare and Family Services (HFS), Child Support Services (CSS) (1-800-447-4278) · Apply online
Give the agency leads
Tell the agency where the other parent works or lives.
Ask about interest
Ask the agency for the total owed, with any interest.
Talk to legal aid
Ask for free help: Illinois Legal Aid Online and Illinois State Bar Association Illinois Lawyer Finder.
Where to get free help in Illinois
Questions about unpaid support in Illinois
How is unpaid child support collected in Illinois?
Arrears means support that is past due. The child support agency can use these tools to collect it: Income withholding (including unemployment benefits); Federal and state tax refund intercept; Comptroller offset; Passport denial or revocation; Driver's license suspension; Professional and hunting/fishing license suspension; Credit bureau reporting; Liens on bank accounts, real estate, personal property and lawsuit settlements; Offset of lottery and casino winnings.
Can a parent be held in contempt for not paying in Illinois?
CSS does not jail parents for not paying, but a judge can order jail after finding a parent in contempt for not following a support order.
Is there interest on unpaid child support in Illinois?
By law, support more than 30 days past due carries interest at 9% a year. Since January 1, 2021, CSS no longer calculates or enforces interest unless a court has ordered it, but you may still owe court-ordered interest. At the end of a case, you can ask HFS in writing to have interest adjudicated.