In Illinois, alimony — also called spousal support or spousal maintenance — is determined at the court's discretion after weighing the length of the marriage, each spouse's income and earning capacity, and the standard of living established during the marriage; there is no single mandatory formula. Our calculator applies common advisory benchmarks to provide a planning estimate for Illinois spousal support.
Illinois alimony is awarded following a divorce or legal separation when one spouse has significantly lower income or earning capacity than the other. Unlike child support, which is calculated under a mandatory statutory formula (750 ILCS 5/505), alimony in Illinois is not determined by a single mandatory formula. Instead, Illinois courts weigh a range of statutory factors to determine whether alimony is appropriate and, if so, the amount and duration most equitable given the facts of the case.
Because alimony decisions in Illinois are highly fact-specific and subject to judicial discretion, the estimates provided here should be treated as a starting point for planning and negotiation, not as a prediction of what a court will actually order. Actual awards can differ substantially based on your judge, the specific facts of your case, and any negotiated agreements reached in mediation. Always consult a licensed family law attorney in Illinois before making financial decisions based on any alimony estimate.
Illinois is a FORMULA state. Under 750 ILCS 5/504, guideline maintenance applies when the parties' combined gross annual income is under $500,000: 33⅓% of the payor's net annual income MINUS 25% of the recipient's net annual income. Cap: the recipient's total income including maintenance cannot exceed 40% of the parties' combined net income.
| Category | Details |
|---|---|
| Formula / Method | (33.3% × payor net income) − (25% × recipient net income), capped so recipient's total ≤ 40% of combined net. |
| Duration | Statutory multiplier × years of marriage: under 5 years = 0.20, 8–9 years = 0.36, 12–13 years = 0.52, 16–17 years = 0.68, 19–20 years = 0.80, 20+ years = duration equal to the marriage or indefinite. |
| Fault | Illinois is pure no-fault; marital misconduct is NOT considered in maintenance. |
| Modification | Modifiable on substantial change in circumstances; guideline review applies. |
| Factor | Typical Impact on Award |
|---|---|
| Length of marriage | High — marriages under 10 years rarely result in permanent alimony |
| Income and earning capacity disparity | High — primary driver of amount; larger gap = larger award |
| Standard of living during marriage | High — courts try to preserve it for the lower-earning spouse |
| Non-economic contributions (homemaking) | Moderate — compensates career sacrifices during marriage |
| Age and health of each spouse | Moderate — poor health or older age limits ability to become self-supporting |
| Marital misconduct / fault | Varies — Illinois law determines whether fault is a permissible factor |
| Time to become self-supporting | Moderate — affects duration; education or training shortens it |