Illinois Maintenance Guideline Calculator
What would the Illinois maintenance guideline set, and for how long? Every piece below can be linked to, so it opens in a window on your reader's screen, current as of the record. No form to fill in.
2026 law · Reviewed September 7, 2026 · The full page, with methodology and sources · the terms · All tools
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Two gross incomes, the years of marriage, and the prior-obligation flag in; the monthly and yearly guideline amount, whether the ceiling binds, the duration, and each spouse's net income before and after. In a frame it carries no cookies, no tracking, and a visible link back to the methodology. Your site has to allow frames; most do. The link that opens it in a small window is on the professionals page.
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- 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.
The facts
Six quotable sentences on the Illinois maintenance guideline.
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- 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)).
- 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.
- 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)).
- 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)).
- 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.
- 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.
Duration by length of the marriage
The multiplier for each band, and what it yields at the band's first year.
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| Length of the marriage at filing | Factor | Guideline duration |
|---|---|---|
| Under 5 years | 0.20 | 0.80 years for a 4-year marriage |
| 5 to under 6 years | 0.24 | 1.20 years for a 5-year marriage |
| 6 to under 7 years | 0.28 | 1.68 years for a 6-year marriage |
| 7 to under 8 years | 0.32 | 2.24 years for a 7-year marriage |
| 8 to under 9 years | 0.36 | 2.88 years for an 8-year marriage |
| 9 to under 10 years | 0.40 | 3.60 years for a 9-year marriage |
| 10 to under 11 years | 0.44 | 4.40 years for a 10-year marriage |
| 11 to under 12 years | 0.48 | 5.28 years for an 11-year marriage |
| 12 to under 13 years | 0.52 | 6.24 years for a 12-year marriage |
| 13 to under 14 years | 0.56 | 7.28 years for a 13-year marriage |
| 14 to under 15 years | 0.60 | 8.40 years for a 14-year marriage |
| 15 to under 16 years | 0.64 | 9.60 years for a 15-year marriage |
| 16 to under 17 years | 0.68 | 10.88 years for a 16-year marriage |
| 17 to under 18 years | 0.72 | 12.24 years for a 17-year marriage |
| 18 to under 19 years | 0.76 | 13.68 years for an 18-year marriage |
| 19 to under 20 years | 0.80 | 15.20 years for a 19-year marriage |
| 20 years or more | Court's discretion | A term equal to the marriage, or indefinite |
Cite and link.
The clean address, a citation generated from the record so it can never carry a stale review date, and an address for every section so you can point a reader at the exact table or method.
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- Link
- https://consideratecapital.com/tools/illinois-maintenance-calculator
- Citation
- Considerate Capital, "Illinois Maintenance Guideline Calculator," reviewed September 7, 2026, https://consideratecapital.com/tools/illinois-maintenance-calculator.
Link to a section
- The calculator https://consideratecapital.com/tools/illinois-maintenance-calculator#calculator
- The facts https://consideratecapital.com/tools/illinois-maintenance-calculator#facts
- The duration table https://consideratecapital.com/tools/illinois-maintenance-calculator#key-numbers
- How the guideline works https://consideratecapital.com/tools/illinois-maintenance-calculator#how-it-works
- Methodology https://consideratecapital.com/tools/illinois-maintenance-calculator#methodology
- Sources https://consideratecapital.com/tools/illinois-maintenance-calculator#sources
- Revision history https://consideratecapital.com/tools/illinois-maintenance-calculator#revision-history
Everything here reads from one reviewed record, so a copied piece carries its year and its review date. When the law moves, the embed updates by itself; a copied table or chart keeps the year in its caption. Corrections are welcome through the contact page.