Estimate Illinois spousal support payments and duration. Free, private, and updated for 2026.
Legal Disclaimer
These calculators provide estimates for educational purposes only. Alimony calculations vary significantly by state, judge, and individual circumstances. Results are not legal advice and do not create an attorney-client relationship. Consult a licensed family law attorney in Illinois for advice specific to your situation.
Illinois enacted a statutory maintenance (alimony) formula in 2015, providing a more predictable framework while retaining judicial discretion for deviation.
Illinois formula: 33.3% of payor's net income minus 25% of recipient's net income, with a cap that the recipient's total income (including maintenance) does not exceed 40% of the parties' combined net income. Duration: marriage length × a multiplier from 0.20 to permanent depending on years married.
Illinois is an equitable distribution state, meaning courts divide marital property fairly but not necessarily equally. The property settlement affects alimony calculations — a spouse who receives significant assets in the divorce may receive less alimony, or none at all, if the property provides sufficient income.
Morgan earns $8,000/month and Casey earns $2,500/month. They were married for 12 years in Illinois. Casey stayed home part-time to raise their children and now works part-time. This is a middle-class marriage with a home, retirement accounts, and modest savings.
This is an estimate only. Actual Illinois alimony depends heavily on the specific judge, Casey's realistic earning capacity with appropriate employment, the property settlement, and other case-specific factors. These numbers should be verified with a licensed Illinois family law attorney.
Length of the Marriage
The length of the marriage is often the single most important factor in Illinois alimony cases. Longer marriages are associated with greater economic interdependence, more sacrifice of career opportunities, and larger gaps in earning capacity. Courts in Illinois generally award longer alimony for longer marriages, and indefinite support becomes more common when a marriage exceeded 20 years.
Earning Capacity Gap
The difference in spouses' incomes and earning potential directly drives alimony calculations in Illinois. A spouse who sacrificed career advancement to raise children or support the other spouse's career may need time and financial support to rebuild earning capacity. Courts consider not just current income but each spouse's realistic earning potential going forward.
Marital Standard of Living
Alimony in Illinois is intended to help maintain a reasonable standard of living consistent with what was established during the marriage. Courts look at the lifestyle the couple shared — housing, vacations, spending habits — and consider how to bridge the gap for a spouse who cannot maintain that standard on their own income. This is why higher-income marriages tend to produce higher alimony awards.
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In Illinois, the duration of alimony depends on the length of the marriage and the requesting spouse's ability to become self-supporting. For marriages under 5 years, alimony is typically awarded for up to half the length of the marriage. For marriages of 5-10 years, up to 60% of the marriage length. For marriages of 10-20 years, up to 75%. For marriages over 20 years, courts may award indefinite alimony in Illinois. Courts retain discretion to modify these general guidelines based on specific circumstances. These are guidelines — actual duration depends on the specific facts of your case.
For divorce agreements finalized after December 31, 2018, alimony is no longer deductible by the payor or includable as income for the recipient under federal law — regardless of state. This change under the Tax Cuts and Jobs Act of 2017 applies in Illinois and all states. For divorce agreements finalized before January 1, 2019, the old tax treatment applies: alimony is deductible by the payor and taxable income for the recipient, unless the agreement was modified to opt into the new rules. If you have a pre-2019 divorce agreement, consult a tax professional about the implications.
In most cases, yes — alimony can be modified in Illinois if there is a substantial change in circumstances. Common qualifying changes include a significant increase or decrease in either spouse's income, the recipient spouse's remarriage (which typically terminates alimony automatically in Illinois), or a major change in health affecting earning capacity. Lump sum alimony is generally not modifiable. Courts in Illinois require filing a motion to modify — simply experiencing a change in circumstances is not enough. The existing alimony order remains in effect until a court enters a new order.
Illinois judges consider multiple factors when determining alimony, including: the length of the marriage, each spouse's income and earning capacity, the marital standard of living, each spouse's contributions to the marriage (including homemaking and child-rearing), the age and health of both parties, the financial resources available to each spouse including marital property awards, and the requesting spouse's ability to become self-supporting. Illinois enacted a statutory maintenance (alimony) formula in 2015, providing a more predictable framework while retaining judicial discretion for deviation. No single factor is determinative — judges weigh all factors together.
In Illinois, adultery generally does not bar alimony or significantly affect the amount, though it may be one of many factors a judge considers. Most states have moved toward no-fault divorce principles that minimize the role of marital misconduct in alimony calculations. The court's primary focus is on the financial needs of the requesting spouse and the payor's ability to pay, regardless of the reasons for the marriage breakdown.