Skip to main content

Illinois Maintenance Guideline Calculator: the facts

2026 law · reviewed September 7, 2026

  1. The guideline applies when the parties' combined gross annual income is under $500,000 and the payor has no child support or maintenance obligation from a prior relationship; otherwise the court sets maintenance from the statutory factors (750 ILCS 5/504(b-1)(1)).
  2. The amount is 33 1/3 percent of the payor's net annual income minus 25 percent of the payee's, and the payee's net income plus maintenance may not exceed 40% of the parties' combined net income (504(b-1)(1)(A)). Whenever the payee earns more than about a fifth of what the payor earns, the ceiling, not the formula, sets the amount.
  3. Duration is the length of the marriage at filing times a factor: .20 under five years, rising four points a year to .80 at nineteen; at twenty years or more the court orders a term equal to the marriage or an indefinite one (504(b-1)(1)(B)).
  4. Net income is the Section 505 figure: gross less the standardized tax amount (federal and state income tax for a single filer with the standard deduction and one exemption, plus FICA), read from the HFS conversion table, or an individualized tax amount when the court allows it (504(b-3.5); 505(a)(3)).
  5. Example: a payor earning $150,000 and a payee earning $50,000, married 12 years. Net incomes of about $106,511 and $40,025; the formula gives $25,497 a year but the 40 percent ceiling cuts it to $18,589, or $1,549 a month, for 6 years and 3 months.
  6. For an instrument executed after 2018, maintenance is neither deductible by the payor nor income to the payee, federally (Pub. L. 115-97 § 11051) and in Illinois, which starts from federal AGI; that is why the guideline was rewritten in 2019 on net rather than gross income.

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.