Illinois Spousal Maintenance Calculator

Amount = 33.33% of the payor's net income minus 25% of the payee's net income, subject to a cap so the payee's combined income does not exceed 40% of combined net income. "Net income" means after-tax income per an accountant's schedule — not gross. The formula applies when combined gross annual income is below $500,000.

Illinois uses a statutory duration table. A 10-year marriage generates 44% of the marriage length (about 5.3 years); a 15-year marriage generates 64% (about 9.6 years). Marriages of 20 years or more may result in permanent maintenance at the court's discretion.

When the parties' combined gross annual income exceeds $500,000, the formula does not automatically apply. The court exercises discretion using the statutory factors listed in 750 ILCS 5/504(a).

Yes, but the court must state its reasons for deviation in writing. This makes Illinois more transparent than most states — if a judge awards a different amount, the order explains why.

Net income. Illinois law requires each party to produce a complete financial disclosure (Form 13.3.1) showing after-tax, after-deduction income. The calculator on this page approximates net as 75% of gross — always get an accountant's figure for accuracy.