Illinois Alimony 2026: How Maintenance Is Calculated

Maintenance vs Alimony: Why Illinois Uses Different Terminology

If you open an Illinois divorce petition, judgment, or wage-withholding order, you will see the word "maintenance." You will not see "alimony," "spousal support," or "separate maintenance" in the statutory text that governs post-divorce payments between spouses. The Illinois Marriage and Dissolution of Marriage Act (IMDMA), codified at 750 ILCS 5, uses "maintenance" exclusively in 750 ILCS 5/504 and related sections.

Why the label matters for research. Google searches, national legal blogs, and generic calculators overwhelmingly use "alimony." Illinois practitioners, circuit court clerks, and the official forms on illinoiscourts.gov use "maintenance." If you file a motion asking for "alimony," a judge will understand what you mean — but your paperwork should track the statute's vocabulary to avoid confusion and to match mandatory financial disclosure forms used in Cook, DuPage, Lake, and downstate counties.

Maintenance is not child support. Illinois child support follows a separate income-shares guideline under 750 ILCS 5/505. Maintenance addresses the supported spouse's need and the payor's ability to pay after property division. Child support addresses the children's needs. Courts run both worksheets in high-gap cases, and the two numbers interact in household budgets — but they are distinct legal obligations with different modification standards and enforcement tools.

Temporary maintenance during litigation is addressed under 750 ILCS 5/501. Final maintenance appears in the judgment of dissolution under 750 ILCS 5/504. The guideline formula in 750 ILCS 5/504(b-1) applies to final awards when statutory prerequisites are met — not to every case automatically.

Illinois is unusual nationally. California has no permanent support formula — judges weigh 14 factors under Cal. Fam. Code § 4320. Maryland has 12 discretionary factors under Md. Code, Fam. Law § 11-106 with no worksheet. Texas restricts court-ordered maintenance to narrow eligibility gates under Tex. Fam. Code § 8.051 before any amount is discussed. Illinois, by contrast, gives qualifying couples a presumptive mathematical answer for both amount and duration. That makes Illinois one of the more calculator-friendly states in the country — provided you understand when the formula applies and when it does not.

The practical takeaway for anyone landing on an "Illinois alimony calculator" page: you are modeling maintenance under 750 ILCS 5/504(b-1). The word "alimony" is fine for search purposes; the legal term is maintenance. The math is what most people actually want.

The Illinois Formula: 33.3% Minus 25%

750 ILCS 5/504(b-1) creates a two-step framework. First, the court determines whether maintenance is appropriate at all by weighing the factors in 750 ILCS 5/504(a) — including each party's income and property, needs, earning capacity, impairment from domestic duties, standard of living, marriage duration, age and health, tax consequences, and any valid agreement between the parties. Second, if maintenance is appropriate and the parties' combined gross annual income is below the statutory threshold in 750 ILCS 5/504(b-1), the court applies the guideline formula unless it makes a written finding that guideline application would be inappropriate.

The guideline amount formula under 750 ILCS 5/504(b-1)(1)(A) is:

• Multiply the payor's monthly net income by 33.3% (one-third) • Multiply the recipient's monthly net income by 25% (one-fourth) • Subtract the second number from the first • The result is the guideline maintenance amount — before the 40% combined income cap

In algebraic form:

Maintenance = (0.333 × payor net) − (0.25 × recipient net)

Worked example (planning only). Payor net income: $8,000/month. Recipient net income: $2,000/month.

33.3% × $8,000 = $2,664 25% × $2,000 = $500 Guideline maintenance = $2,664 − $500 = $2,164/month

Before accepting $2,164 as the final number, run the 40% combined income cap described in the next section. In this example, 40% of combined net income ($10,000) is $4,000. Because $2,164 is less than $4,000, the cap does not reduce the formula result.

When the formula does not apply. If combined gross annual income exceeds the threshold in 750 ILCS 5/504(b-1) — currently $500,000 — courts determine amount and duration using the discretionary factors in 750 ILCS 5/504(a) without the guideline math. Executive compensation, professional partnerships, and closely held business income often push cases above the threshold. Even below the threshold, a judge may deviate from the guideline amount or duration with written findings that application would be inappropriate under the circumstances.

Deviation requires explanation on the record. Illinois appellate courts expect trial judges to calculate the guideline number first, then explain why deviation is warranted if they depart. Skipping the math entirely without findings is a common reversal theme in maintenance appeals.

Property division interacts with the formula. Awards under 750 ILCS 5/503 shift income-producing assets and debt payments between spouses. A recipient who receives a large marital home with equity may have reduced maintenance need; a payor saddled with marital debt may argue inability to pay the guideline figure after child support under 750 ILCS 5/505. Do not double-count dollars already allocated in equitable distribution.

Use TheLegalCalc's Illinois alimony calculator to run the 33.3%/25% formula with your net income inputs, then verify the cap and duration bands before negotiating or filing.

The 40% Cap: When It Applies

The Illinois formula can produce a large number when income gaps are wide. The legislature added a ceiling so maintenance does not leave the recipient with an outsized share of combined household net income. Under 750 ILCS 5/504(b-1)(1)(A), the guideline maintenance amount cannot exceed 40% of the parties' combined net income.

How to apply the cap in three steps:

Step 1 — Calculate combined monthly net income. Add the payor's net and the recipient's net.

Step 2 — Multiply combined net by 40%. That product is the maximum allowable maintenance payment under the cap.

Step 3 — Compare the formula result to the cap. If the formula exceeds the cap, the cap controls. If the formula is lower, the formula controls.

Cap check on the $8,000 / $2,000 example. Combined net = $10,000/month. Forty percent of $10,000 = $4,000. Formula result = $2,164/month. Because $2,164 < $4,000, the cap does not reduce the award.

When the cap bites — high income gaps. Payor net: $15,000/month. Recipient net: $1,000/month.

33.3% × $15,000 = $4,995 25% × $1,000 = $250 Formula = $4,745/month

Combined net = $16,000. Cap = 40% × $16,000 = $6,400. Formula $4,745 < $6,400 — cap still does not apply in this scenario.

Now push the gap further. Payor net: $20,000/month. Recipient net: $500/month.

33.3% × $20,000 = $6,660 25% × $500 = $125 Formula = $6,535/month

Combined net = $20,500. Cap = 40% × $20,500 = $8,200. Still below cap.

The cap becomes decisive when the formula output itself exceeds 40% of combined net — most common when the recipient earns very little or nothing and the payor earns very high net income relative to the combined total. Example: Payor net $12,000, recipient net $0.

Formula = 33.3% × $12,000 = $3,996/month Combined net = $12,000. Cap = $4,800. Formula still below cap.

Example where cap applies: Payor net $9,000, recipient net $0.

Formula = $2,997/month Combined = $9,000. Cap = $3,600. Formula below cap.

The cap is one reason Illinois maintenance awards feel "capped" in high-earner cases even though the 33.3%/25% formula looks generous on paper. Always run both calculations.

Statutory nuance. Some practitioners also analyze whether the recipient's total income including maintenance would exceed 40% of combined net under alternative readings of the statute's payee-receipt language. When in doubt, model both the formula-only cap and the payee-total cap with counsel — county practice can vary in how judges apply the written finding requirements for deviation.

The 40% cap is Illinois's answer to a problem discretionary states handle through judicial temperance. In California, a judge might award less than a 40%/50% temporary heuristic after weighing § 4320 factors. In Illinois, the cap is built into the statute for guideline cases.

How Duration Is Calculated in Illinois

Amount and duration are separate calculations under 750 ILCS 5/504(b-1). After computing the guideline maintenance amount (subject to the 40% cap), courts turn to 750 ILCS 5/504(b-1)(1)(B) for guideline duration. Duration is expressed as a percentage of the length of the marriage, measured in years, with the marriage length typically calculated from the date of marriage to the date of filing for dissolution.

Illinois duration multipliers by marriage length:

• Less than 5 years: multiply marriage length by 0.20 (20%) • 5 to 10 years: multiply marriage length by 0.40 (40%) • 10 to 15 years: multiply marriage length by 0.60 (60%) • 15 to 20 years: multiply marriage length by 0.80 (80%) • 20 years or more: permanent maintenance or maintenance for a period equal to the length of the marriage, at the court's discretion

Examples across the bands:

3-year marriage (under 5 years): 3 × 0.20 = 0.6 years — about 7 months of guideline duration.

8-year marriage (5–10 year band): 8 × 0.40 = 3.2 years — about 3 years and 2 months.

12-year marriage (10–15 year band): 12 × 0.60 = 7.2 years.

18-year marriage (15–20 year band): 18 × 0.80 = 14.4 years.

22-year marriage (20+ years): permanent maintenance or maintenance for 22 years — the court chooses between indefinite support and a fixed term equal to the marriage length.

Permanent does not mean unmodifiable. Even "permanent" maintenance under Illinois law remains subject to modification under 750 ILCS 5/510 when circumstances change, and termination events in the judgment (remarriage, death, cohabitation if specified) still apply. Permanent means no fixed end date in the order — not immunity from later court review.

Courts may deviate from guideline duration with written findings, just as they may deviate from guideline amount. A recipient who can become self-supporting quickly may receive a shorter term; a disabled recipient in a 12-year marriage may receive longer support than the 7.2-year guideline suggests.

Compare to Florida's post-2023 durational caps (50%/60%/75% of marriage length depending on duration band under Fla. Stat. § 61.08) or Texas's hard statutory maximums under Tex. Fam. Code § 8.054 for eligible spouses. Illinois's band structure is more granular at the low end (20% for very short marriages) and opens the door to permanence at 20+ years — a different policy choice than Florida's elimination of new permanent alimony.

Negotiation tip. Duration percentages are easier to stipulate than amount when incomes are disputed. Many Illinois settlements fix duration at the guideline band midpoint and negotiate amount separately.

What Counts as Net Income in Illinois

Illinois maintenance uses net income, not gross W-2 wages. That single definitional choice separates Illinois from states like Virginia, where pendente lite support formulas typically use gross income. Getting net income wrong is the most common spreadsheet error in Illinois maintenance calculations.

For maintenance guideline purposes, net income means gross income minus the following deductions:

• Federal income tax (actual withholding or reasonable estimate) • State income tax (Illinois flat rate applies to most residents) • Social Security (FICA) contributions • Medicare contributions • Mandatory health insurance premiums (the employee's share of health coverage when enrollment is mandatory or de facto required)

What gross income includes. W-2 wages, salaries, commissions, bonuses, overtime, and most self-employment receipts before the deductions above. Rental income, investment income, and pension distributions may count depending on how the court characterizes them under the child support net income definitions cross-referenced in maintenance practice.

What is typically excluded from deductions. Voluntary retirement contributions above mandatory amounts, union dues, life insurance, and charitable deductions are generally not subtracted when computing net income for maintenance — though local practice and individual judges vary on edge cases.

Self-employed payors. Net income for business owners is not simply "what hit the personal bank account." Courts may add back excessive depreciation, personal expenses run through the business, and discretionary deductions. Schedule C income, K-1 distributions, and retained earnings arguments appear constantly in Cook County and collar-county maintenance trials. Bring three years of tax returns, not one.

Imputed income. If a party is voluntarily unemployed or underemployed, Illinois courts may impute income based on earning capacity under 750 ILCS 5/504(a)(2) and related case law. Imputation can flip the payor/recipient designation in edge cases where the higher-educated spouse refuses to work.

Interaction with child support net definitions. Illinois child support under 750 ILCS 5/505 uses its own net income definition with a longer list of allowable deductions (including mandatory retirement contributions in some configurations). Maintenance and child support worksheets should be run separately with the correct definition for each — do not copy the child support net figure into a maintenance calculator without verifying the deduction lists align.

Illinois vs gross-income states. Texas maintenance, when ordered at all, references gross income caps under Tex. Fam. Code § 8.055. New York maintenance under DRL § 236-B uses a payor/payee formula on income concepts defined in that article. Illinois's net-income base produces lower nominal inputs than gross-income formulas for the same W-2 — but the 33.3%/25% percentages are applied to those lower numbers. Always compare net-to-net when benchmarking against other states.

Practical documentation. Attach pay stubs showing gross, federal tax, state tax, FICA, Medicare, and health premium lines. For the supported spouse returning to work, document job search efforts — imputation cuts both ways.

Step-by-Step: Two Complete Examples

The following walkthroughs combine amount, cap, and duration in full — the way a mediator or financial affidavit preparer should run the numbers before a settlement conference.

Example 1 — Eight-year marriage

Facts. Payor net income: $10,000/month. Recipient net income: $1,500/month. Marriage length: 8 years. Combined gross income below the $500,000 statutory threshold. No basis for deviation.

Step 1 — Guideline amount.

33.3% × $10,000 = $3,330 25% × $1,500 = $375 Formula maintenance = $3,330 − $375 = $2,955/month

Step 2 — 40% cap.

Combined net = $10,000 + $1,500 = $11,500 Cap = 40% × $11,500 = $4,600 $2,955 < $4,600 → cap does not reduce the amount

Step 3 — Duration.

Eight-year marriage falls in the 5–10 year band → multiplier 0.40 Duration = 8 × 0.40 = 3.2 years (approximately 3 years and 2 months)

Planning summary. Guideline maintenance of $2,955/month for approximately 3.2 years, subject to court findings that maintenance is appropriate and that guideline application is not inappropriate.

Example 2 — Twenty-two-year marriage

Facts. Payor net income: $6,000/month. Recipient net income: $0/month (not currently employed). Marriage length: 22 years.

Step 1 — Guideline amount.

33.3% × $6,000 = $1,998 25% × $0 = $0 Formula maintenance = $1,998/month

Step 2 — 40% cap.

Combined net = $6,000 Cap = 40% × $6,000 = $2,400 $1,998 < $2,400 → cap does not reduce the amount

Step 3 — Duration.

Twenty-two-year marriage falls in the 20+ year band → permanent maintenance or maintenance for a period equal to the length of the marriage (22 years), at the court's discretion.

Planning summary. Guideline maintenance of $1,998/month with indefinite or long-term duration — the most significant financial component in this scenario is not the monthly amount but the open-ended length of payments.

Side-by-side comparison. The eight-year marriage produces a higher monthly payment ($2,955 vs $1,998) but a firm end date near 3.2 years. The twenty-two-year marriage produces a lower monthly payment but potentially decades of obligation. Total dollars over time can exceed the short-marriage/high-payment scenario dramatically — always multiply monthly amount by duration when comparing settlement packages.

Additional sanity check — simple two-income example. Payor net $8,000, recipient net $2,000, 6-year marriage.

Amount: $2,664 − $500 = $2,164/month. Cap: 40% × $10,000 = $4,000 — no reduction. Duration: 6 × 0.40 = 2.4 years (5–10 year band).

Run your own numbers in TheLegalCalc's Illinois alimony calculator before stipulating. Print the output for your financial affidavit file.

Modifying Maintenance in Illinois

Maintenance orders are not necessarily frozen for the entire duration. Modification is governed by 750 ILCS 5/510. Unless the parties validly agreed otherwise in a settlement, the court may modify maintenance only upon a showing of a substantial change in circumstances.

What counts as substantial. Illinois courts have recognized many scenarios as substantial changes: involuntary job loss, disability, serious health changes, large pay increases or decreases, retirement, and completed retraining that makes the recipient self-supporting. A change of 20% or more in a party's income is often treated as presumptively substantial in Illinois modification practice — though the moving party still must petition the court and prove the change with updated financial affidavits.

750 ILCS 5/510(a-5) frames the general modification standard for maintenance. Related provisions address reviewability of non-modifiable agreements, retirement timing, and termination. Read your judgment carefully: some settlement agreements waive modification or limit it to specific triggers.

Common modification scenarios:

Job loss by the payor. A payor laid off from a $180,000 position who accepts a $95,000 replacement job may have a substantial change argument — especially if the reduction is involuntary and documented with WARN notices, unemployment filings, and good-faith job search records.

Income increase by the recipient. A recipient who completes a degree and doubles income during a rehabilitative maintenance term may face a reduction motion by the payor.

Retirement. Payors approaching normal retirement age sometimes seek modification or termination. Illinois case law on retirement and maintenance is fact-intensive — age, assets received in property division, and the recipient's independent resources all matter.

Cohabitation. Unlike remarriage (which typically terminates maintenance if the judgment so provides), cohabitation with a new partner does not automatically end Illinois maintenance unless the order or agreement specifies a cohabitation trigger. Some judgments include step-down or termination clauses for marriage-like relationships — verify your decree.

Do not self-modify. Stopping or reducing payments without a court order creates arrears, interest, and contempt exposure. File a motion to modify in the circuit court that issued the judgment. Cook County, DuPage, Lake, Will, and downstate counties have local rules on motion practice, mediation, and financial disclosure updates.

Agreements that waive modification. If your marital settlement agreement says maintenance is non-modifiable, the court may be bound by that language if it was knowing and voluntary. Non-modifiable maintenance trades flexibility for certainty — common in high-asset Chicago divorces where the recipient accepts a lump-sum property offset.

Enforcement vs modification. A modification motion changes the future obligation. Citation for contempt addresses past-due amounts. Keep those remedies separate in strategy discussions with counsel.

Cross-reference child support modification. Illinois child support modification has a separate 20% guideline-inconsistency pathway under 750 ILCS 5/510(a)(2)(A). A change that triggers child support review may not automatically satisfy maintenance modification standards — run both analyses if both obligations exist.

Illinois vs Other States: Formula vs Discretion

Illinois occupies a middle ground between formula-driven states and pure discretion states — but leans formula for qualifying couples.

Illinois vs California. California has no statutory permanent support formula. Temporary support in many counties follows informal 40%/50% net-income heuristics, but final awards are entirely discretionary under Cal. Fam. Code § 4320's 14 factors. Illinois gives a presumptive number for couples under the combined income threshold. Predictability favors Illinois for planning; flexibility favors California for advocacy.

Illinois vs New York. New York maintenance under DRL § 236-B uses a two-step formula (30% of payor minus 20% of payee) with its own income caps and duration formulas for many cases. Illinois uses 33.3%/25% on net income with the 40% combined cap. Both are formula states, but the percentages, income definitions, and cap mechanics differ — do not import New York results into an Illinois negotiation.

Illinois vs Texas. Texas is not a formula state for maintenance. Court-ordered spousal maintenance requires eligibility under Tex. Fam. Code § 8.051 (10+ year marriage with inability to earn, disability, or family violence pathways, among others). Amount is capped at the lesser of 20% of gross income or $5,000/month under § 8.055, with duration limits in § 8.054. Illinois applies the formula to many more divorces without Texas's narrow gates.

Illinois vs Florida. Florida eliminated new permanent alimony in 2023 under CS/SB 1416 (Fla. Stat. § 61.08). Durational caps tie to marriage length at 50%/60%/75%, and amount is capped at the lesser of need or 35% of the net income difference. Illinois's 20+ year band can produce permanent maintenance — a fundamentally different long-marriage outcome.

Illinois vs Virginia. Virginia's only widely used formula is pendente lite temporary support (27%/50% of gross income under Va. Code § 16.1-278.17:1 practice). Permanent alimony is discretionary under 13 factors. Virginia also bars adulterous spouses from permanent support under § 20-107.1(B) — Illinois has no equivalent automatic bar.

Illinois vs Maryland. Maryland has no formula at all under § 11-106. Practitioners use pattern-based ranges. Illinois's statutory worksheet gives a starting number Maryland lacks.

Why Illinois's formula matters for calculators. TheLegalCalc can produce tighter Illinois estimates than discretionary-state tools because 750 ILCS 5/504(b-1) supplies real math — provided combined income is below the threshold and the court does not deviate. Competitor sites that apply a generic "30% of payor income" rule to Illinois are wrong on both the percentages and the net-income base.

The honest limitation. Above $500,000 combined gross income, Illinois reverts to discretion. Adultery, property division, and imputed income can shift results below the threshold. The formula is powerful but not universal.

Illinois Courts and the Calculator

Start with official resources before you file or settle.

Illinois Courts. The Illinois Courts website at illinoiscourts.gov hosts self-help materials, mandatory financial disclosure forms, and links to circuit court local rules. Cook County's Domestic Relations Division publishes detailed scheduling orders and financial affidavit requirements that mirror the net income concepts used in maintenance calculations.

Statutory text. Read the current version of 750 ILCS 5/504 at ilga.gov — search for "750 ILCS 5/504" in the Illinois Compiled Statutes. Threshold amounts, duration bands, and deviation standards change when the legislature amends the IMDMA. Always verify the text in force on your filing date.

Use TheLegalCalc's Illinois alimony calculator to model:

• Guideline amount using 33.3% of payor net minus 25% of recipient net • The 40% combined net income cap • Duration bands based on marriage length (<5 years at 0.20; 5–10 at 0.40; 10–15 at 0.60; 15–20 at 0.80; 20+ permanent or marriage length)

Bring to an Illinois family law attorney:

• Three years of tax returns and six months of pay stubs for both spouses • A completed net income worksheet showing each deduction line • Marriage length in years and months (filing date matters) • Property division summary from 750 ILCS 5/503 • Any agreement language on modification or waiver

Contested maintenance trials in Cook and collar counties routinely cost tens of thousands in attorney fees — calculator output is the inexpensive part. Use the formula to narrow your settlement band; use counsel to bind the result in a judgment that survives enforcement and modification motions.

Mediation. Many Illinois counties require mediation before contested hearings. Arrive with the guideline number, cap analysis, and duration band already calculated — mediators respect parties who did the math.

Final reminder. Illinois calls it maintenance. The formula under 750 ILCS 5/504(b-1) is what most people mean when they search for alimony. Run the numbers, then verify every assumption with a licensed Illinois family law attorney before signing a marital settlement agreement.