Illinois Maintenance (Alimony) Laws: The Formula Explained (2026)
Illinois Maintenance (Alimony) Laws: The Formula Explained (2026)
Illinois does not use the word "alimony." The state calls it maintenance, and a statutory formula under 750 ILCS 5/504 sets both the amount and the duration when the parties' combined gross annual income falls below $500,000.
Information last verified on June 1, 2026.
Estimate your situation: Try our free Illinois alimony calculator to estimate spousal support and see the factors a Illinois court weighs.
What is maintenance in Illinois?
Maintenance is the Illinois term for what most people call alimony or spousal support. It is a periodic payment from one former spouse to the other after divorce, designed to address income disparities and support a spouse who sacrificed career opportunities during the marriage.
The legal authority is the Illinois Marriage and Dissolution of Marriage Act, specifically 750 ILCS 5/504. The statute was significantly modernized in 2015 to introduce the guideline formula. Before the formula existed, every maintenance award was discretionary, which produced inconsistent results across courtrooms.
A court must first decide whether maintenance is appropriate at all. That threshold decision is guided by 14 statutory factors listed in 750 ILCS 5/504(a), including each party's income and property, realistic earning capacity, any impairment caused by time devoted to domestic duties, the standard of living during the marriage, the duration of the marriage, the tax consequences of the award, and the age, health, and needs of each party.
Only after the court finds maintenance is warranted does it apply the formula to calculate amount and duration.
The Illinois maintenance formula: amount calculation and the 40% cap
When the formula applies, the amount of maintenance is calculated in two steps.
Step 1: Compute the raw figure.
Take 33 1/3% of the payer's net annual income and subtract 25% of the recipient's net annual income. The result is the annual maintenance guideline amount.
For example: if the payer's net annual income is $120,000 and the recipient's net annual income is $40,000, the raw calculation is (1/3 x $120,000) minus (0.25 x $40,000), which equals $39,960 minus $10,000, or $29,960 per year (about $2,497 per month).
Step 2: Apply the 40% cap.
The statute requires that the maintenance amount, when added to the recipient's net income, must not give the recipient more than 40% of the parties' combined net income. This cap protects against a situation where the formula would result in the recipient earning more than the payer after maintenance.
Using the same example: combined net income is $160,000. Forty percent of that is $64,000. The recipient already earns $40,000, so the maximum maintenance is $64,000 minus $40,000, or $24,000 per year. The raw formula produced $29,960, which exceeds the cap, so maintenance is capped at $24,000 per year.
"Net income" for purposes of the formula generally means gross income minus federal and state income taxes, Social Security taxes, Medicare taxes, and mandatory retirement contributions, though courts may make adjustments in contested cases.
The formula produces a guideline number. Even when the formula applies, a court may deviate from the guideline amount if it makes a written finding that applying the guideline would be inappropriate, considering the 14 statutory factors.
How long maintenance lasts: the duration multipliers by marriage length
The duration of maintenance is calculated by multiplying the length of the marriage (measured at the time the divorce action was filed) by a statutory factor. The factor increases as the marriage grows longer. Under 750 ILCS 5/504(b-1)(1)(B), the multipliers are:
| Length of Marriage | Duration Multiplier |
|---|---|
| Less than 5 years | 0.20 |
| 5 years to less than 6 years | 0.24 |
| 6 years to less than 7 years | 0.28 |
| 7 years to less than 8 years | 0.32 |
| 8 years to less than 9 years | 0.36 |
| 9 years to less than 10 years | 0.40 |
| 10 years to less than 11 years | 0.44 |
| 11 years to less than 12 years | 0.48 |
| 12 years to less than 13 years | 0.52 |
| 13 years to less than 14 years | 0.56 |
| 14 years to less than 15 years | 0.60 |
| 15 years to less than 16 years | 0.64 |
| 16 years to less than 17 years | 0.68 |
| 17 years to less than 18 years | 0.72 |
| 18 years to less than 19 years | 0.76 |
| 19 years to less than 20 years | 0.80 |
| 20 years or more | Court discretion: period equal to marriage length, or indefinite term |
For example, a 12-year marriage carries a multiplier of 0.52. Multiply 12 years by 0.52 and maintenance lasts 6.24 years (about 6 years and 3 months).
For marriages of 20 or more years, the court has discretion to order maintenance for a period equal to the length of the marriage or for an indefinite (permanent) term. Neither outcome is automatic. The court weighs the statutory factors, including the recipient's realistic ability to become self-supporting, before selecting the duration.
Courts designate the type of maintenance in the order: fixed-term, reviewable, or indefinite. Fixed-term maintenance ends on the date stated in the order and generally cannot be extended unless the recipient files a timely petition. Reviewable maintenance lasts for a stated period, after which a court evaluates the circumstances before deciding whether to continue, modify, or terminate it.
When the formula does not apply
The guideline formula is mandatory (absent a finding of inappropriateness) only when two conditions are met:
- The parties' combined gross annual income is less than $500,000.
- The payer has no obligation to pay child support or maintenance from a prior relationship.
If either condition is missing, the court does not use the formula. It still considers all 14 statutory factors listed in 750 ILCS 5/504(a) and has full discretion over both the amount and duration of any maintenance award.
The $500,000 threshold is based on combined gross annual income, not net income. When income exceeds that threshold, the formula is not binding, though a court may still use it as a reference point.
The "prior relationship" condition means that a payer who is already paying child support or maintenance from a first marriage is not subject to the guideline formula in a second divorce. Again, the court uses the 14-factor test to set any new award.
Even when both conditions are met, a court may deviate from the formula if it makes a written finding explaining why the guideline amount or duration would be inappropriate. Common grounds include extreme disparity in non-marital assets, a business interest that distorts net income, or health conditions that affect earning capacity.
How maintenance ends or changes
Automatic termination. Under 750 ILCS 5/510(c), maintenance terminates by operation of law when the recipient remarries or when either party dies. The payer is entitled to a refund of any maintenance paid after the termination date.
Cohabitation. If the recipient lives with another person on a resident, continuing conjugal basis, a court may terminate maintenance. Cohabitation does not end maintenance automatically; the payer must file a petition and prove the relationship. The court evaluates factors such as the duration of the cohabitation, whether the parties share finances, and the nature of the relationship.
Modification based on a substantial change in circumstances. Either party may petition the court to modify the amount or duration of maintenance if there has been a substantial change in circumstances since the last order. 750 ILCS 5/510(a-5) lists relevant factors, including changes in income, the recipient's progress toward self-sufficiency, and the tax consequences of any modification. Courts generally apply modifications only to payments due after the petition was filed.
Review hearings. If the original order is designated "reviewable," the court schedules a hearing at the end of the review period. The recipient bears the burden of demonstrating a continued need. The payer may argue that the recipient has had sufficient time to become self-supporting.
Fixed-term expiration. When fixed-term maintenance expires, it ends. A recipient who does not timely petition for extension before the termination date generally loses the right to seek continued maintenance.
Is maintenance taxable, and how it differs from Illinois child support
Federal tax treatment for post-2018 agreements. The Tax Cuts and Jobs Act of 2017 eliminated the deduction for maintenance payers and the income-inclusion requirement for recipients for any divorce or separation agreement executed after December 31, 2018. Under current federal law (see IRS Topic 452), the payer cannot deduct maintenance payments and the recipient does not report them as taxable income.
Pre-2019 agreements. For divorce agreements signed before January 1, 2019, the old rules still apply unless the parties specifically modify the agreement and elect the new treatment. Under the old rules, the payer deducts maintenance as an above-the-line deduction and the recipient reports it as ordinary income.
Illinois state income tax. Illinois conforms to the federal treatment. Payers under post-2018 agreements do not deduct maintenance on their Illinois return, and recipients do not report it as income.
How maintenance differs from child support. Illinois child support is calculated under a separate statute (750 ILCS 5/505) using an income shares model. Child support is paid for the benefit of a child, not a former spouse. It is never deductible by the payer and is never taxable to the recipient, regardless of the year of the agreement. Child support ends when the child turns 18 (or graduates high school, up to age 19) and is not subject to modification for cohabitation or remarriage of either parent. Maintenance, by contrast, is tied to the former spouse's circumstances and terminates on remarriage.
When both obligations exist, the court determines them separately. The presence of a child support obligation does not arithmetically reduce maintenance, but it is one factor the court may consider when deciding whether the guideline formula is appropriate.
For more information about alimony rules nationwide, see alimony laws by state.
Legal Disclaimer: This page provides general legal information about Illinois maintenance law for educational purposes only. It is not legal advice and does not create an attorney-client relationship. Maintenance awards depend on the specific facts of each case. Consult a licensed Illinois family law attorney for advice about your situation.
More Illinois Laws
- Illinois AI Meeting Recording Laws
- Illinois Car Seat Laws
- Illinois Child Support Laws
- Illinois Data Privacy Laws
- Illinois Dog Bite Laws
- Illinois Emancipation Laws
- Illinois Expungement Laws
- Illinois Hit and Run Laws
- Illinois Lemon Laws
- Illinois Power of Attorney Laws
- Illinois Recording Laws
- Illinois Sexting Laws
- Illinois Squatters Rights Laws
- Illinois Statute of Limitations
- Illinois Whistleblower Laws
Sources
- Illinois General Assembly, 750 ILCS 5/504 (Maintenance): https://www.ilga.gov/legislation/ilcs/documents/075000050k504.htm
- Illinois General Assembly, 750 ILCS 5/510 (Modification and termination of maintenance): https://www.ilga.gov/documents/legislation/ilcs/documents/075000050k510.htm
- Internal Revenue Service, Topic No. 452, Alimony and Separate Maintenance: https://www.irs.gov/taxtopics/tc452
- Illinois General Assembly, 750 ILCS 5/505 (Child Support): https://www.ilga.gov/legislation/ilcs/documents/075000050k505.htm
Last updated: June 1, 2026.