Family Law Playbook — Illinois Edition · Step 8 of 12
Maintenance in Illinois
The statutory formula, duration multipliers, and how courts decide maintenance under 750 ILCS 5/504
Researched by Dan Martin, Legal Researcher · Published by Onbello Legal
Illinois uses a maintenance formula
Illinois uses “maintenance” as the statutory term for what many other states call alimony or spousal support. Unlike states where maintenance is entirely discretionary, Illinois has a statutory formula under 750 ILCS 5/504 that applies when the combined gross annual income of both parties is less than $500,000 and the payor has no obligation to pay child support or maintenance from a prior relationship.
The formula gives both parties predictability about what maintenance will be and for how long. Courts must apply the formula unless there are specific reasons to deviate, and any deviation must be explained in a written finding.
The formula: 33.33% minus 25%
The Illinois maintenance formula calculates the annual maintenance amount as follows:
Maintenance = (33.33% × payor's net annual income) − (25% × payee's net annual income)
“Net income” for maintenance purposes uses the same calculation as child support: gross income minus allowable taxes and deductions.
Example: Payor earns $120,000 net per year. Payee earns $40,000 net per year.
- 33.33% of $120,000 = $40,000
- 25% of $40,000 = $10,000
- Maintenance = $40,000 − $10,000 = $30,000 per year ($2,500/month)
The 40% combined income cap
Duration: marriage length × multiplier
The duration of maintenance is calculated by multiplying the length of the marriage (in years) by a statutory multiplier. The longer the marriage, the larger the multiplier, and the longer maintenance runs.
| Marriage length | Multiplier | Example (10-year marriage) |
|---|---|---|
| Under 5 years | × 0.20 | — |
| 5–6 years | × 0.24 | — |
| 6–7 years | × 0.28 | — |
| 7–8 years | × 0.32 | — |
| 8–9 years | × 0.36 | — |
| 9–10 years | × 0.40 | — |
| 10–11 years | × 0.44 | 10 × 0.44 = 4.4 years |
| 11–12 years | × 0.48 | — |
| 12–13 years | × 0.52 | — |
| 13–14 years | × 0.56 | — |
| 14–15 years | × 0.60 | — |
| 15–16 years | × 0.64 | — |
| 16–17 years | × 0.68 | — |
| 17–18 years | × 0.72 | — |
| 18–19 years | × 0.76 | — |
| 19–20 years | × 0.80 | — |
| 20+ years | Court discretion | Equal to the length of the marriage, or indefinite |
Marriages of 20 or more years
What maintenance terminates on
Maintenance automatically terminates upon:
- Death of either party
- Remarriage of the maintenance recipient
- Cohabitation of the recipient on a resident, continuing conjugal basis (not merely dating — the standard requires a relationship akin to marriage)
Maintenance can also be modified or terminated on a showing of substantial change in circumstances of either party under 750 ILCS 5/510, such as a significant change in income for either the payor or the recipient.
When the formula does not apply
The statutory formula applies only when the combined gross annual income of both parties is less than $500,000. When combined gross income reaches or exceeds $500,000, the court uses the discretionary factors under 750 ILCS 5/504, which include:
- The income and property of each party
- The needs of each party
- The present and future earning capacity of each party
- Impairment of earning capacity due to domestic responsibilities
- Duration of the marriage
- The standard of living established during the marriage
- Each party's contribution to the other's career or education
- Tax consequences of the property division
- Valid agreements of the parties (prenuptial agreements)
Common questions
How is maintenance (alimony) calculated in Illinois?
Under 750 ILCS 5/504, Illinois maintenance is calculated as 33.33% of the payor's net income minus 25% of the payee's net income. However, the total of maintenance plus the payee's net income cannot exceed 40% of the parties' combined net income. Duration is based on a multiplier tied to the length of the marriage (for example, 0.20 for marriages of less than 5 years, increasing to 0.80 for marriages of 19 years or more but less than 20 years). For marriages of 20 or more years, if the court awards maintenance, it orders maintenance, in its discretion, for a period equal to the length of the marriage or for an indefinite term.
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