How the Illinois child support calculator works
This Illinois child support calculator follows 750 ILCS 5/505 and the HFS Support Obligation Worksheet.[1][5]
- Gross income from all sources, excluding means-tested benefits and support received for other children.
- Standardized net income from the HFS Gross to Net Income Conversion Table. The parent with the majority of overnights is treated as claiming the children for tax purposes.[3]
- Adjustments. Subtract support actually paid for other children under an order (and maintenance, which this calculator leaves out).
- Basic obligation. Find combined net income in the 2026 Schedule of Basic Obligations, in $50 brackets with no interpolation.[2]
- Shares. The paying parent owes their percentage of combined net income times the basic obligation.
- Health insurance. The premium for the children is split by income share and added or credited depending on who pays it.
The 2026 gross-to-net table
Standardized net income subtracts federal and Illinois income tax for a single filer and FICA, using two allowances for the majority-time parent and one for the other parent.[3][4] Our calculator reads the official table directly; outside its $325 to $30,024.99 range it applies the same tax method, which reproduces all 1,188 cells of the table.
| Gross income | Net, majority-time parent | Net, other parent |
|---|---|---|
| $2,000 | $1,706 | $1,658 |
| $3,500 | $2,845 | $2,790 |
| $5,000 | $3,976 | $3,921 |
| $7,500 | $5,665 | $5,574 |
| $10,000 | $7,300 | $7,205 |
A court can use an individualized tax amount instead, for example when the parties agree or after a hearing on the parents’ actual tax situation.[1]
Schedule of basic obligations
The 2026 schedule runs from $25 to $27,374.99 of combined net income a month; above that, the court decides, but not below the top-row amount.[1][2]
| Combined net income | 1 child | 2 children | 3 children | 4 children |
|---|---|---|---|---|
| $2,000 | $461 | $702 | $848 | $948 |
| $4,000 | $921 | $1,378 | $1,656 | $1,849 |
| $6,000 | $1,211 | $1,808 | $2,142 | $2,393 |
| $8,000 | $1,444 | $2,137 | $2,507 | $2,801 |
| $10,000 | $1,686 | $2,499 | $2,938 | $3,282 |
| $15,000 | $2,269 | $3,302 | $3,806 | $4,251 |
Shared physical care at 146 overnights
When each parent has at least 146 overnights a year, the basic obligation is multiplied by 1.5, each parent’s share is multiplied by the other parent’s percentage of overnights, and the parent who owes more pays the difference.[1][6] A change already enacted lowers the threshold to 110 overnights for cases from January 1, 2027, with a smaller adjustment between 110 and 145 overnights.[1]
Low-income minimum order
When the paying parent’s gross income is at or below 75% of the federal poverty guideline, $997.50 a month in 2026, there is a rebuttable presumption of $40 a month per child, up to $120 in total.[1][4] A parent with no income, or who cannot work because of a medically proven disability, incarceration or institutionalization, is presumed to owe $0.
Health insurance, child care and other expenses
Health insurance premiums for the children are split by income share: if the receiving parent pays, the paying parent’s share is added; if the paying parent pays, the other parent’s share is credited.[1] Neither applies if the parent who would owe it has net income below 133% of the poverty guideline. Child care, extracurricular and school costs are allocated by income share at the court’s discretion and appear separately from the basic obligation on the HFS worksheet.[5]
Official Illinois estimator and agency
The Department of Healthcare and Family Services publishes the tables, the worksheets and its own Child Support Estimator.[8][9]
- HFS Child Support Estimator
- HFS Income Shares tables and worksheets
- HFS Division of Child Support Services
Other income shares states read their schedules differently: see the Ohio child support calculator (gross income, yearly table) and the PA child support calculator (net income, nearest row). For a broader view, read how much child support is by state.
An estimate, not an order. The court decides the amount. Not legal advice; see our legal disclaimer.
Frequently asked questions
How much is child support in Illinois?
It is the paying parent’s share of the schedule amount for both parents’ combined net income. For example, combined net income of $6,000 gives a basic obligation of $1,211 for one child, and a parent with 60% of the income owes $726.60.
Is the Illinois child support calculator 2026 up to date?
Yes. It uses the HFS Schedule of Basic Obligations and the Gross to Net Income Conversion Table that took effect March 20, 2026.
How many overnights reduce child support in Illinois?
146 or more for each parent triggers the shared physical care formula. From January 1, 2027 the threshold is 110 overnights.
What is the minimum child support in Illinois?
$40 a month per child, up to $120, when the paying parent’s gross income is at or below 75% of the poverty guideline ($997.50 a month in 2026).
Sources
- 750 ILCS 5/505, Child support
- 2026 Illinois Schedule of Basic Obligations
- 2026 Gross to Net Income Conversion Table Using Standardized Tax Amounts
- 2026 Addendum to the Illinois Schedule of Basic Obligations and Standardized Net Income Table
- Support Obligation Worksheet
- Shared Physical Care Support Obligation Worksheet
- Income Shares FAQs
- Child Support Estimator
- Income Shares (schedules, worksheets and updates)