Illinois Maintenance Guideline Calculator
750 ILCS 5/504(b-1) · reviewed September 7, 2026
Shows the monthly maintenance the Illinois guideline formula produces from two incomes and the length of the marriage, and how long it would last. AboutLess
In plain words. Maintenance is what Illinois calls alimony. For most divorces the law sets it by formula: a third of the paying spouse's net income, minus a quarter of the receiving spouse's net income, with a ceiling so the receiving spouse ends up with no more than 40 percent of the couple's combined net income. How long it lasts is the length of the marriage times a factor that grows with the years. Net income means income after taxes, figured a standard way, and this tool approximates that figure from the year's tax rules.
Why it matters. Whether you would pay or receive it, the formula sets the starting point every negotiation begins from. Knowing the number, and whether the ceiling or the formula is setting it, tells you what is actually being argued about.
An example. A paying spouse earning $150,000 and a receiving spouse earning $50,000, married 12 years: net incomes of about $106,500 and $40,000. The formula gives about $25,500 a year, but the 40 percent ceiling cuts it to about $18,600, or $1,549 a month, for 6 years and 3 months.
Where it stops. The formula applies only when the two incomes together are under $500,000 and the paying spouse has no support obligation from an earlier relationship. The court can depart from it, and its net income figure comes from a state table this tool only approximates. Child support in the same case, a marriage of 20 years or more, and orders entered before 2019 all change the arithmetic. Everything it leaves out.
Income from all sources before any tax is taken out. The tool treats it as wages.
The same figure for the other spouse. Enter 0 if there is none.
Whole years from the wedding to the day the petition was filed.
- How long maintenance lasts
- 6 years and 3 months
- 12 years of marriage times 0.52
- Paying spouse's net income after maintenance
- $87,921
- From $106,511 after taxes, before the transfer
- Receiving spouse's net income after maintenance
- $58,614
- From $40,025 after taxes, before the transfer
Net income here is an approximation. The tool subtracts federal income tax for a single filer with the standard deduction, Illinois income tax after the personal exemption, and Social Security and Medicare tax. The court uses the state's standardized net income table, or an individualized tax figure when the facts call for one, so the court's numbers will differ a little. For an order entered after 2018, maintenance is not deductible by the paying spouse and is not income to the receiving spouse.
This follows the Illinois maintenance guidelines with the 2026 federal and Illinois tax figures. It assumes both incomes are wages, a single filer with the standard deduction for each spouse, whole years of marriage, and no child support in the same case. It leaves out the court's power to depart from the guidelines, the 50 percent limit when child support is also ordered, orders entered before 2019 that are still deductible, and credit for temporary maintenance already paid. Educational, not advice.
This is a simplified model, not your actual tax return or plan. It only knows what you type in, leaves out rules that may apply to you, and cannot weigh the other facts and trade-offs a real decision depends on. Before you act, talk with a professional who knows your whole situation.
Educational only, not investment, tax, or legal advice. Results are hypothetical estimates that vary with each use and over time and are not guaranteed accurate or complete. Using this tool creates no client relationship with Considerate Capital, and the site that linked here is not affiliated with it. By using it you agree to the tool terms.