Illinois Alimony & Spousal Support (2026)
Illinois is one of the few states with an actual guideline formula for alimony amount, under 750 ILCS 5/504. It's still advisory in most cases — a judge can deviate from it — but it gives a real, citable starting point instead of pure guesswork.
The guideline formula
Illinois is one of the few states with a real statutory maintenance formula. When the combined gross annual income of both parties is below the statutory cap and no other exceptional circumstances apply, the guideline amount is 33 1/3% of the payor's net annual income minus 25% of the payee's net annual income. The amount is capped so that, when added to the payee's own net income, the payee does not end up with more than 40% of the combined net income of both parties.
Duration is set by multiplying the length of the marriage by a statutory factor: under 5 years = 0.20, 5-6 years = 0.24, 6-7 years = 0.28, 7-8 years = 0.32, 8-9 years = 0.36, 9-10 years = 0.40, 10-11 years = 0.44, 11-12 years = 0.48, 12-13 years = 0.52, 13-14 years = 0.56, 14-15 years = 0.60, 15-16 years = 0.64, 16-17 years = 0.68, 17-18 years = 0.72, 18-19 years = 0.76, 19-20 years = 0.80. For marriages of 20 years or more, the court may order maintenance for a period equal to the length of the marriage or for an indefinite term.
What determines alimony in Illinois
Under 750 ILCS 5/504 (Illinois Marriage and Dissolution of Marriage Act), a court considers:
- Each party's income and property, including marital property apportioned to them
- Each party's needs
- Present and future earning capacity
- Impairment of earning capacity due to devoting time to domestic duties or having forgone education/training/employment during the marriage
- Time needed for the party seeking maintenance to acquire education/training/employment
- The standard of living established during the marriage
- The duration of the marriage
- The age, health, and occupation of both parties
- Sources of income, including retirement and medical benefits
- Tax consequences of the property division on each party
- Contributions to the education, training, or career of the other spouse
- Any valid agreement of the parties
- Any other factor the court expressly finds just and equitable
Good to know
- This formula applies as a rebuttable guideline in most cases below the statutory income cap. A judge can deviate from the guideline amount or duration if applying it would be inequitable, and the formula does not apply automatically above the income cap or in every case.
- This is not a calculator — the numbers above describe the statutory method, they are not computed for your specific income here.
Also need a child support estimate?
Alimony and child support are calculated completely separately in Illinois. If you also have children, use our free Illinois child support calculator — that one does compute a real number, based on the official guideline formula.
Frequently asked questions
Is there a real alimony formula in Illinois?
Yes. Illinois is one of only a handful of states with an actual statutory maintenance formula (750 ILCS 5/504), rather than pure judge discretion. Under the guideline, maintenance is 33 1/3% of the payor's net income minus 25% of the payee's net income, capped so the recipient's total doesn't exceed 40% of the combined net income.
How long does alimony last in Illinois?
Duration is set by a statutory table that multiplies the length of the marriage by a factor that rises with marriage length — from 0.20 for marriages under 5 years up to 0.80 for marriages of 19-20 years. Marriages of 20 years or longer can result in maintenance equal to the marriage length or an indefinite term.
Is the Illinois maintenance formula guaranteed?
No. The formula is the guideline amount for cases that qualify (generally where combined income is below the statutory cap), but a judge can deviate from it if the statutory factors make the guideline amount unfair. It's a strong starting point, not a guarantee.
Source: Illinois Marriage and Dissolution of Marriage Act · Last verified 2026-07-22
Disclaimer: This page explains the general legal framework for alimony in Illinois and is for informational purposes only — it is not legal advice and does not predict the outcome of any specific case. Laws change; always verify with the official source above or a family law attorney licensed in Illinois before making decisions.