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Illinois Spousal Support Calculator

Estimate Illinois maintenance (alimony) payments using the 2025 statutory formula. Calculate both payment amount and duration based on the Illinois Marriage and Dissolution of Marriage Act.

📋

Illinois Formula (2019 Law)

Amount: (33.33% × Payer's Net Income) - (25% × Recipient's Net Income) • Cap: Recipient cannot exceed 40% of combined income

📊 Calculate Your Maintenance Estimate

💰 Annual Net Income

Net income = Gross income minus taxes, Social Security, Medicare, and mandatory retirement contributions

💍 Marriage Duration

Estimated Monthly Maintenance

$1,333

$16,000 per year

📐 Calculation Breakdown

33.33% of Payer's Income$33,330
25% of Recipient's Income- $10,000
Annual Maintenance$16,000

⚠️ 40% Cap Applied: The calculated amount was reduced from $23,330 to $16,000 so the recipient's total income ($56,000) doesn't exceed 40% of combined income ($56,000).

⏱️ Payment Duration

Marriage Length10 years
Duration Multiplier44%
Estimated Duration4.4 years (53 months)
Estimated Total Payments$70,400

Based on $16,000/year × 4.4 years

📅 Illinois Maintenance Duration Chart

Duration is calculated as a percentage of the marriage length

Years MarriedDuration MultiplierExample Duration
0-5 years20%0.0 years
5-6 years24%1.2 years
6-7 years28%1.7 years
7-8 years32%2.2 years
8-9 years36%2.9 years
9-10 years40%3.6 years
10-11 years44%4.4 years
11-12 years48%5.3 years
12-13 years52%6.2 years
13-14 years56%7.3 years
14-15 years60%8.4 years
15-16 years64%9.6 years
16-17 years68%10.9 years
17-18 years72%12.2 years
18-19 years76%13.7 years
19-20 years80%15.2 years
20+ years100% or Permanent20+ years or permanent

How Illinois Spousal Support is Calculated

Illinois uses a statutory formula established in the Illinois Marriage and Dissolution of Marriage Act (750 ILCS 5/504). The formula was updated in 2019 to use net income instead of gross income.

The Formula

Maintenance = (33.33% × Payer's Net Income) - (25% × Recipient's Net Income)

1

Calculate Net Income

Gross income minus taxes, Social Security, Medicare, and mandatory retirement.

2

Apply the Formula

Take 33.33% of the payer's net income and subtract 25% of the recipient's net income.

3

Check the 40% Cap

Recipient's total income (their income + maintenance) cannot exceed 40% of combined net income.

4

Determine Duration

Use the duration chart based on marriage length (20% to 100% of marriage years).

What is "Net Income" for Illinois Maintenance?

Net income for spousal maintenance in Illinois is defined in 750 ILCS 5/505. It starts with all income from various sources and subtracts mandatory deductions:

✅ Included in Gross Income

  • Salary and wages
  • Bonuses and commissions
  • Self-employment income
  • Investment income
  • Rental income
  • Pension/retirement income

➖ Deducted from Gross

  • Federal income taxes
  • State income taxes
  • Social Security (FICA)
  • Medicare
  • Mandatory retirement contributions
  • Union dues (if mandatory)

📊 Key Numbers

Payer's Share33.33%
Recipient's Share25%
Income Cap40%
Guidelines Limit$500K

⚠️ Important Notes

  • This is an estimate only
  • Courts may deviate from guidelines
  • Many factors affect final amounts
  • Consult with an Illinois family law attorney
  • Tax treatment changed in 2019

Frequently Asked Questions

Illinois uses a statutory formula: (33.33% × Payer's Net Income) - (25% × Recipient's Net Income) = Annual Maintenance. The result cannot cause the recipient's total income to exceed 40% of the combined net income. This formula applies when combined gross income is under $500,000.

The '1/3 rule' refers to the 33.33% (one-third) of the payer's net income used in Illinois' maintenance formula. The full calculation takes 33.33% of the payer's net income and subtracts 25% of the recipient's net income to determine the support amount.

Factors that may disqualify or reduce alimony include: having sufficient income/assets to support yourself, short marriage duration, misconduct during marriage, cohabitation with a new partner, ability to work but choosing not to, or if combined income exceeds $500,000 (court discretion applies).

Either spouse can request maintenance if they lack sufficient income to meet reasonable needs. Courts consider: each spouse's income and property, standard of living during marriage, duration of marriage, age and health of both parties, contributions to the marriage (including homemaking), and career sacrifices made.

Duration is based on marriage length. For marriages under 5 years, support lasts 20% of the marriage length. The percentage increases by 4% for each additional year, up to 80% for 19-20 year marriages. For marriages of 20+ years, courts may order permanent maintenance or a duration equal to the marriage length.

For divorces finalized after December 31, 2018, maintenance payments are NOT tax-deductible for the payer and NOT taxable income for the recipient. This is due to the Tax Cuts and Jobs Act of 2017 which changed the federal tax treatment of alimony.

Yes, maintenance can be modified if there's a substantial change in circumstances, such as job loss, significant income change, remarriage of the recipient, or cohabitation. Either party can petition the court for modification. Some agreements include provisions that prevent modification.

⚖️ Disclaimer: This calculator provides estimates based on the Illinois statutory guidelines (750 ILCS 5/504) for informational purposes only. It is not legal advice. Actual maintenance amounts may vary based on many factors considered by the court. Always consult a licensed Illinois family law attorney for guidance specific to your situation.