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 the statutory factors listed in 750 ILCS 5/504(a). The statute numbers them (1) through (14) but adds a factor (6.1), so there are 15 enumerated considerations in all. They include each party's income and property, realistic earning capacity, any impairment caused by time devoted to domestic duties, the effect of any parental responsibility arrangements on a party's ability to seek or maintain employment, 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 $40,000 minus $10,000, or $30,000 per year (about $2,500 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 $30,000, 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 statutory factors in 750 ILCS 5/504(a).

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:

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:

1. The parties' combined gross annual income is less than $500,000.
2. 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 of the 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 statutory-factor test in 750 ILCS 5/504(a) 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. If your fixed term is nearing its end date, ask an Illinois family lawyer for a free case evaluation on petitioning for an extension before it expires (attorney advertising).

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.

The statute does supply one concrete limit on the combined burden. Under 750 ILCS 5/504(b-1), if applying guideline maintenance produces a combined maintenance and child support obligation that exceeds 50% of the payer's net income, the court may set non-guideline maintenance, non-guideline child support under 750 ILCS 5/505(a)(3.4), or both.

For more information about alimony rules nationwide, see alimony laws by state.

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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.

Last updated: June 1, 2026.

More Illinois Laws

• Illinois Child Custody Laws
• Illinois Child Support Laws
• Illinois Common Law Marriage Laws
• Illinois Divorce Laws

Frequently Asked Questions

Does Illinois use the word alimony?

No. Illinois calls spousal support 'maintenance.' The term 'alimony' has no legal significance in Illinois courts. The governing statute is 750 ILCS 5/504 of the Illinois Marriage and Dissolution of Marriage Act.

How is the maintenance amount calculated in Illinois?

The guideline formula takes 33 1/3% of the payer's net annual income and subtracts 25% of the recipient's net annual income. The result is the annual maintenance amount, subject to a cap: the maintenance award cannot push the recipient's total income above 40% of the parties' combined net income.

How long does maintenance last in Illinois?

Duration is calculated by multiplying the length of the marriage by a statutory factor. The factor starts at 0.20 for marriages under 5 years and increases by 0.04 for each additional year, reaching 0.80 for a marriage of 19 to 20 years. For marriages of 20 or more years, the court may order maintenance for a period equal to the marriage length or for an indefinite term.

When does the formula not apply in Illinois?

The formula does not apply when the parties' combined gross annual income is $500,000 or more, or when the payer already has a child support or maintenance obligation from a prior relationship. In those cases, the court uses its discretion based on the statutory factors in 750 ILCS 5/504(a), which the statute numbers (1) through (14) plus a factor (6.1).

Does maintenance end if the recipient starts living with a new partner?

Not automatically. Unlike remarriage, cohabitation does not terminate maintenance by operation of law. The payer must file a petition in court and prove that the recipient is living with another person on a resident, continuing conjugal basis. If proven, a court may terminate maintenance from the date cohabitation began.

Is maintenance taxable in Illinois?

For agreements signed after December 31, 2018, federal law does not allow the payer to deduct maintenance, and the recipient does not report it as income. Illinois follows this federal treatment. For agreements signed before 2019, the old rules generally still apply: deductible for the payer and taxable to the recipient.

Can a maintenance order be modified after divorce?

Yes. 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. Common grounds include a significant change in income, the recipient's new employment or education, or retirement. The court generally applies changes only from the date the petition was filed.