Illinois guideline maintenance formula
How Illinois calculates guideline maintenance (alimony).
The guideline starts with one-third of the paying spouse’s annual net income, less one-quarter of the receiving spouse’s. A second limit prevents the payment plus the recipient’s net income from exceeding 40% of combined net income. The calculator shows both calculations and uses the lower result, floored at zero. [1]
⅓ of payer net income − ¼ of recipient net income
Then apply the combined-net-income limit. A zero arithmetic result does not settle entitlement.
Guideline duration uses marriage length at commencement of the action. Court decisions and possible credit for temporary maintenance can change the outcome. The tool explains the limits alongside the number. [1]
Questions about the Illinois alimony calculation.
Can I enter the amount on my paycheck?
Not automatically. Illinois uses a statutory net-income definition. This calculator asks you to supply that figure; it does not calculate deductions or convert a paycheck deposit into statutory income. [2]
What happens when my case is outside the tool’s scope?
The result area says “No amount calculated.” It does not display $0, borrow another state’s formula, or imply that support is unavailable.
Are the example figures a recommendation?
No. “Try example figures” loads a fictional case to demonstrate the interface and calculation steps. Change every applicable figure and answer before exploring your own illustration.
Illinois alimony sources and calculator limits
- 01Illinois General Assembly: 750 ILCS 5/504, maintenance
- 02Illinois General Assembly: 750 ILCS 5/505, statutory income definitions
Public-source check: September 6, 2026. Current calculator rules release: 0.18.0. Source checking and automated testing are not attorney review or a guarantee of legal correctness.