Illinois Child Support
Estimate for Illinois
Illinois uses the Income Shares model.
Official schedule: Illinois HFS, '2026 Addendum to the Illinois Schedule of Basic Obligations and Standardized Net Income Table' (submitted to IL Dept. of Healthcare and Family Services, Division of Child Support Services, Mar. 13, 2026). (2026)
View calculation breakdown
| Combined parental income | $9,000 |
|---|---|
| Total basic obligation (schedule) | $2,351 |
| Obligor income share | 55.6% |
| Obligor basic obligation | $1,306 |
| Estimated monthly support | $1,306 |
How the basic obligation splits between parents
Estimated monthly support by number of children
§ How Illinois calculates support
Illinois uses the Income Shares model under 750 ILCS 5/505 (effective July 2017, replacing the old percentage-of-obligor model). It starts from each parent's gross income, subtracts a standardized or individualized tax amount to reach net income, then applies the Schedule of Basic Child Support Obligations. The Division of Child Support Services (HFS) updates the schedule and gross-to-net conversion table annually. Health insurance and childcare add-ons are allocated; deviations require written findings stating the guideline amount.
Content verified against official sources on 2026-08-09.
✦ How to open or modify a case in Illinois
- Apply through the HFS Division of Child Support Services or file in court (dissolution, parentage, or support action).
- Establish parentage if unmarried (voluntary acknowledgment or court testing).
- Both parents provide income data; use the free Illinois Child Support Estimator / Income Shares worksheet (HFS).
- The court enters an order based on the guideline; deviations beyond the worksheet require written findings.
- Support is paid via income withholding; HFS enforces.
- To modify, file a motion showing a substantial change in circumstances; the worksheet is recalculated.
◈ Illustrative examples
Scenario: Parent A net $1,000/mo; Parent B net $500/mo; combined net $1,500/mo; one child.
Walk-through: From the Illinois schedule, the basic obligation for $1,500 combined net and one child ≈ $325 (illustrative schedule figure from HFS documentation). Parent A = 67% → 0.67 × $325 ≈ $217/mo, plus their share of add-ons (health insurance, childcare).
Takeaway: Illinois allocates the basic obligation by each parent's percentage of combined net income.
Scenario: Parent with higher gross income but several dependents.
Walk-through: Illinois converts gross to net using either the HFS standardized tax table or the parent's actual individualized tax amount; the chosen net figure drives the schedule lookup.
Takeaway: Because Illinois uses net income, the gross-to-net conversion (standardized table or actual taxes) materially affects the result.
? Frequently asked questions
↗ Official policy & agency links
Sources verified: https://hfs.illinois.gov/childsupport · https://ilga.gov · 750 ILCS 5/505 (Illinois Marriage and Dissolution of Marriage Act)