Illinois calculates alimony duration — called "maintenance" under state law — by multiplying the length of the marriage by a statutory percentage ranging from 20% to 80%. A 10-year marriage yields approximately 4.4 years of maintenance, while marriages lasting 20 years or longer may result in indefinite or permanent awards under 750 ILCS 5/504(b-3). The guideline formula applies only when the combined gross income of both spouses falls below $500,000 per year. Courts retain discretion to deviate from the formula based on 14 statutory factors outlined in 750 ILCS 5/504(a).
| Key Fact | Detail |
|---|---|
| Legal Term | Maintenance (not "alimony") |
| Governing Statute | 750 ILCS 5/504 |
| Duration Formula | Marriage length x statutory multiplier (0.20–0.80) |
| 20+ Year Marriages | Indefinite or equal to marriage length |
| Income Cap for Guidelines | $500,000 combined gross income |
| Amount Formula | 33.33% of payor's net income minus 25% of payee's net income |
| Payment Cap | Payee cannot receive more than 40% of combined net income |
| Filing Fee | $250–$388 depending on county (as of March 2026) |
| Residency Requirement | 90 days in Illinois (750 ILCS 5/401) |
| Grounds | No-fault only (irreconcilable differences) |
| Tax Treatment | Not deductible by payor, not taxable to recipient (post-2018) |
How Illinois Calculates Maintenance Duration
Illinois determines how long alimony lasts by applying a fixed multiplier to the number of years the marriage lasted at the time of filing. A marriage of 5 years produces maintenance lasting 1.2 years (5 x 0.24), while a 15-year marriage produces maintenance lasting 9.6 years (15 x 0.64). The formula under 750 ILCS 5/504(b-3) eliminates much of the guesswork that existed before Illinois adopted guideline maintenance on January 1, 2019. For marriages lasting 20 years or more, the court may award maintenance for a period equal to the entire length of the marriage or designate the award as indefinite.
The full statutory multiplier table governs every guideline maintenance case in Illinois:
| Marriage Length | Multiplier | Example Duration |
|---|---|---|
| Under 5 years | 0.20 | 4-year marriage = 0.8 years |
| 5 to under 6 years | 0.24 | 5-year marriage = 1.2 years |
| 6 to under 7 years | 0.28 | 6-year marriage = 1.68 years |
| 7 to under 8 years | 0.32 | 7-year marriage = 2.24 years |
| 8 to under 9 years | 0.36 | 8-year marriage = 2.88 years |
| 9 to under 10 years | 0.40 | 9-year marriage = 3.6 years |
| 10 to under 11 years | 0.44 | 10-year marriage = 4.4 years |
| 11 to under 12 years | 0.48 | 11-year marriage = 5.28 years |
| 12 to under 13 years | 0.52 | 12-year marriage = 6.24 years |
| 13 to under 14 years | 0.56 | 13-year marriage = 7.28 years |
| 14 to under 15 years | 0.60 | 14-year marriage = 8.4 years |
| 15 to under 16 years | 0.64 | 15-year marriage = 9.6 years |
| 16 to under 17 years | 0.68 | 16-year marriage = 10.88 years |
| 17 to under 18 years | 0.72 | 17-year marriage = 12.24 years |
| 18 to under 19 years | 0.76 | 18-year marriage = 13.68 years |
| 19 to under 20 years | 0.80 | 19-year marriage = 15.2 years |
| 20+ years | Court discretion | Equal to marriage length or indefinite |
The multiplier increases by 0.04 for each additional year of marriage between 5 and 20 years. Illinois courts apply the marriage length measured from the date of the marriage to the date the petition for dissolution was filed, not the date of the final judgment. This distinction matters because contested divorces in Illinois can take 18 to 24 months to finalize.
How Illinois Calculates the Maintenance Amount
Illinois maintenance equals 33.33% of the payor's net annual income minus 25% of the payee's net annual income, subject to a cap that prevents the payee from receiving more than 40% of the combined net income of both spouses. For example, if the payor earns $120,000 net annually and the payee earns $40,000 net annually, the guideline calculation produces $40,000 minus $10,000, yielding $30,000 per year in maintenance. The 40% cap on combined net income of $160,000 limits maintenance to $24,000 per year in this scenario because the payee's total income ($40,000 + $30,000 = $70,000) would exceed 40% of $160,000 ($64,000). The amount formula is codified in 750 ILCS 5/504(b-1).
The guideline formula applies only when the combined gross annual income of both spouses is less than $500,000. Above that threshold, courts exercise full discretion using the 14 statutory factors in 750 ILCS 5/504(a). The formula also does not apply if the payor has existing child support or maintenance obligations from a prior relationship. Net income for maintenance purposes is defined by cross-reference to 750 ILCS 5/505 and includes income from all sources minus standardized or individualized tax amounts.
When Alimony Ends in Illinois: Termination Events
Illinois maintenance terminates automatically upon the death of either party or the remarriage of the recipient under 750 ILCS 5/510(c). Cohabitation by the recipient with another person on a "resident, continuing conjugal basis" does not terminate maintenance automatically but gives the payor grounds to petition the court for termination. The recipient must provide the payor with at least 30 days' notice of intent to remarry, or 72 hours' notice if the decision to remarry occurs within that 30-day window. If maintenance payments continue after remarriage or the onset of cohabitation, the payor is entitled to full reimbursement of all amounts paid after the triggering event.
Fixed-term maintenance ends on the date specified in the court order with no further judicial review, and the right to maintenance is permanently barred after expiration. Indefinite maintenance has no set termination date and continues until the court modifies or terminates it based on a substantial change in circumstances. Reviewable maintenance includes a court-designated review date at which the judge reassesses both parties' financial situations and determines whether to continue, modify, or terminate the award. These three designations are established in 750 ILCS 5/504(b-4.5).
Fixed-Term, Indefinite, and Reviewable Maintenance Compared
Illinois courts designate every maintenance award as one of three types under 750 ILCS 5/504(b-4.5), and the designation fundamentally changes how long alimony lasts in Illinois. Fixed-term awards are most common for marriages under 20 years, while indefinite and reviewable awards predominate for longer marriages. The court must specify which type applies in the dissolution judgment, and each type carries different rights and obligations for both parties.
| Feature | Fixed-Term | Indefinite | Reviewable |
|---|---|---|---|
| End Date | Specified in order | None | Review date specified |
| Automatic Termination | Yes, on end date | No | No |
| Court Review | Not available | Available on petition | Built-in review hearing |
| Right to Extend | Barred after term expires | N/A | Court decides at review |
| Typical Marriage Length | Under 20 years | 20+ years | 20+ years |
| Modification | Only before term expires | Substantial change required | Reassessed at review date |
| Death/Remarriage | Terminates immediately | Terminates immediately | Terminates immediately |
Reviewable maintenance offers a middle ground for marriages near the 20-year threshold. The court sets a review date — often 5 to 10 years after the initial award — at which point the recipient must demonstrate continued need and the payor's continued ability to pay. At the review hearing, the court applies the factors in 750 ILCS 5/504(a) and makes specific findings under subdivision (b-8) before deciding whether maintenance should continue.
The 14 Factors Illinois Courts Consider
Illinois courts evaluate 14 factors under 750 ILCS 5/504(a) when deciding whether to award maintenance, how much to award, and how long alimony should last in Illinois. These factors apply in every case but carry greatest weight when the combined gross income exceeds $500,000 or when the court exercises its discretion to deviate from the guideline formula. The statute directs courts to consider "all relevant factors" including each party's income, property, needs, earning capacity, standard of living during the marriage, and contributions to the other spouse's career or education.
The most outcome-determinative factors in Illinois maintenance cases are the duration of the marriage, the disparity in earning capacity between the spouses, and the standard of living established during the marriage. A spouse who left the workforce for 15 years to raise children will receive greater weight on the impairment-of-earning-capacity factor than a spouse who maintained continuous employment throughout the marriage. Courts also consider any prenuptial or postnuptial agreements, tax consequences of the property division, and the age and health of both parties. The 14th factor is a catch-all that permits the court to consider "any other factor that the court expressly finds to be just and equitable."
2025 Law Change: Incarceration and Maintenance
Public Act 103-967, effective January 1, 2025, eliminated the automatic suspension of maintenance during the payor's incarceration. Before this change, Illinois courts routinely suspended maintenance obligations when the payor was imprisoned, and no arrears accumulated during the period of incarceration. Under the new law, maintenance payments continue to accrue as arrears even while the payor is incarcerated. The incarcerated payor must affirmatively petition the court for a modification of the maintenance order, and the court will evaluate the petition under the standard modification framework of 750 ILCS 5/510.
This change aligns Illinois with the growing national trend of placing the burden on the payor to seek modification rather than granting automatic relief. Recipients of maintenance in Illinois should be aware that arrears now accumulate during incarceration and can be enforced through contempt proceedings, wage garnishment, or other collection mechanisms upon the payor's release. The change applies only to maintenance orders entered or modified after January 1, 2025.
Tax Treatment of Maintenance in Illinois
Maintenance payments in Illinois divorces finalized after December 31, 2018, are tax-neutral: the payor cannot deduct maintenance payments, and the recipient does not report them as taxable income. This change resulted from the Tax Cuts and Jobs Act of 2017, which repealed the federal alimony deduction under former 26 U.S.C. Section 71 for all divorce agreements executed after 2018. Illinois updated its guideline formula simultaneously to use net income instead of gross income, ensuring the formula accounts for the loss of the deduction.
Divorce agreements finalized before January 1, 2019, retain the prior tax treatment: payments are deductible by the payor and included in the recipient's taxable income. This grandfathering rule continues to apply even if the order is subsequently modified, unless the modification expressly states that the new tax rules apply. The distinction between pre-2019 and post-2018 orders directly affects how long alimony lasts in Illinois because the net income calculation produces different guideline amounts than the former gross income calculation, which in turn affects the likelihood that a court will deviate from the formula.
Filing for Divorce in Illinois: Requirements and Costs
Illinois requires at least one spouse to have resided in the state for a minimum of 90 consecutive days before the court can enter a final judgment of dissolution under 750 ILCS 5/401. The petition can be filed before the 90-day residency period is satisfied, but the judge will not finalize the divorce until residency is established. Illinois is a purely no-fault divorce state, meaning the only available ground for dissolution is irreconcilable differences. Filing fees range from $250 to $388 depending on the county, with Cook County charging the highest fee at $388 and counties like Kane County charging approximately $295. As of March 2026, verify current fees with your local clerk of court.
The responding spouse pays an appearance fee ranging from $181 to $251 depending on the county. Fee waivers are available under Illinois Supreme Court Rule 298 for households at or below 125% of the federal poverty guidelines. Beyond filing fees, the total cost of a contested divorce in Illinois ranges from $15,000 to $30,000 or more depending on the complexity of asset division and custody disputes, while an uncontested divorce typically costs between $1,500 and $5,000 including attorney fees.
Modifying Maintenance Duration in Illinois
Either party can petition to modify the duration or amount of maintenance upon showing a substantial change in circumstances under 750 ILCS 5/510. Common grounds for modification include a significant increase or decrease in either party's income, the recipient's completion of job training or education that substantially improves earning capacity, a change in the payor's health that impairs earning ability, or the recipient's cohabitation with a new partner. The court evaluates modification petitions using the same 14 factors applied in the original maintenance determination under 750 ILCS 5/504(a).
Fixed-term maintenance cannot be extended beyond its original end date, making the designation of the maintenance type at the time of the original order critically important. If the court designates maintenance as fixed-term, the right to maintenance is permanently barred once the term expires regardless of changed circumstances. Indefinite and reviewable maintenance orders remain subject to modification throughout their duration. Illinois courts will not modify maintenance retroactively — modifications take effect from the date of filing the petition for modification, not from the date circumstances changed.
How Cohabitation Affects Alimony Duration in Illinois
Cohabitation by the maintenance recipient with another person on a "resident, continuing conjugal basis" provides grounds for the payor to petition for termination of maintenance under 750 ILCS 5/510(c). Unlike remarriage, which terminates maintenance automatically by operation of law, cohabitation requires the payor to file a petition and prove to the court that the recipient is living with a new partner in a conjugal relationship. Illinois courts examine factors including whether the parties share a residence, share expenses, maintain a sexual relationship, and hold themselves out as a couple when determining whether a conjugal cohabitation exists.
The payor bears the burden of proving cohabitation, and Illinois courts have held that merely spending frequent overnights at a partner's home does not necessarily constitute residing together on a continuing conjugal basis. If the court finds that cohabitation exists, it may terminate maintenance entirely or reduce the amount. The payor is entitled to reimbursement of all maintenance payments made after the date cohabitation began. Cohabitation claims are among the most litigated maintenance issues in Illinois family courts because the statutory definition leaves substantial room for judicial interpretation.
Frequently Asked Questions
How long does alimony last in Illinois for a 10-year marriage?
Illinois maintenance for a 10-year marriage lasts approximately 4.4 years under the statutory formula. The court multiplies the marriage length (10 years) by the applicable multiplier (0.44) from the duration table in 750 ILCS 5/504(b-3). This applies when combined gross income is below $500,000. The court may designate this as fixed-term, meaning maintenance is permanently barred after 4.4 years.
Can alimony be permanent in Illinois?
Illinois courts may award indefinite maintenance for marriages lasting 20 years or longer under 750 ILCS 5/504(b-3). Indefinite maintenance has no termination date and continues until modified by the court, or terminated by death, remarriage, or proven cohabitation. For marriages of 20+ years, the court may also set the duration equal to the full length of the marriage rather than designating it as indefinite.
Does remarriage end alimony in Illinois?
Remarriage of the recipient terminates Illinois maintenance automatically by operation of law under 750 ILCS 5/510(c). The recipient must provide 30 days' notice to the payor before remarrying. If maintenance payments continue after remarriage, the payor is entitled to full reimbursement. No court petition is required — termination occurs immediately upon the remarriage date.
How is the maintenance amount calculated in Illinois?
Illinois calculates maintenance as 33.33% of the payor's net income minus 25% of the payee's net income under 750 ILCS 5/504(b-1). A cap prevents the payee from receiving more than 40% of the combined net income of both spouses. The formula applies only when combined gross income is below $500,000 per year. Above that threshold, courts use 14 statutory factors with full discretion.
Can Illinois maintenance be modified after the divorce?
Either party may petition to modify maintenance upon demonstrating a substantial change in circumstances under 750 ILCS 5/510. Changes in income, health, employment, or the recipient's cohabitation qualify as modification grounds. Fixed-term maintenance cannot be extended beyond its original end date, while indefinite and reviewable maintenance remain modifiable throughout their duration. Modifications take effect from the filing date of the petition.
Is alimony taxable in Illinois?
Maintenance payments in Illinois divorces finalized after December 31, 2018, are not taxable to the recipient and not deductible by the payor following the Tax Cuts and Jobs Act of 2017. Pre-2019 divorce agreements retain the former tax treatment where payments are deductible by the payor and taxable to the recipient. The applicable tax rule depends on the date the divorce was finalized, not the date payments are made.
What happens to alimony during incarceration in Illinois?
Since January 1, 2025, under Public Act 103-967, maintenance payments continue to accrue as arrears during the payor's incarceration. The incarcerated payor must affirmatively petition the court for a modification. Before this change, Illinois courts automatically suspended maintenance obligations during imprisonment. Arrears accumulated during incarceration can be enforced through contempt proceedings or wage garnishment upon release.
Does cohabitation end alimony in Illinois?
Cohabitation does not automatically terminate maintenance in Illinois, unlike remarriage. The payor must file a petition and prove the recipient is living with another person on a "resident, continuing conjugal basis" under 750 ILCS 5/510(c). If proven, the court may terminate or reduce maintenance. The payor is entitled to reimbursement of payments made after cohabitation began.
What is the difference between reviewable and fixed-term maintenance?
Fixed-term maintenance ends on the specified date with no right to extend, and maintenance is permanently barred after expiration. Reviewable maintenance includes a built-in court review date where the judge reassesses both parties' circumstances under 750 ILCS 5/504(b-4.5). At review, maintenance may be continued, modified, or terminated. Reviewable awards are most common for marriages near or exceeding 20 years.
How much does it cost to file for divorce in Illinois?
Illinois divorce filing fees range from $250 to $388 depending on the county, with Cook County charging $388 and Kane County charging approximately $295 as of March 2026. The responding spouse pays an appearance fee of $181 to $251. Fee waivers are available under Illinois Supreme Court Rule 298 for households at or below 125% of federal poverty guidelines. Total contested divorce costs typically range from $15,000 to $30,000.