Illinois Alimony Calculator

Illinois applies a strict mathematical guideline.

Illinois applies a strict formula after its 2019 reform: maintenance equals 33⅓% of the payor’s net income minus 25% of the payee’s net income, and the payee’s total may not exceed 40% of the parties’ combined net income. The payor’s net income is estimated here at 75% of gross, and child support for one child (20% of net) is deducted from the payor’s base when children are involved.

Because Illinois uses a formula, this calculator returns a precise point estimate or statutory band rather than a judgment call. The exact arithmetic is shown in the step-by-step math drawer of the calculator above.

Duration: 750 ILCS 5/504(a-6): the term equals a statutory percentage of the marriage — 20% under 5 years, 40% for 5–10 years, 60% for 10–15 years, 80% for 15–20 years, and 100% at 20 years or more.

Settlement planning

Lump-Sum Alimony Buyouts & Post-Support Cash Flow in Illinois

Most Illinois support awards are agreed as a set of monthly payments — but the same money can be settled in one payment up front. That trade is called an alimony buyout: instead of writing a check every month for years, the payer hands over a single lump sum today, often by letting the recipient keep more of the house or more of a retirement account, so both spouses can move on cleanly. Illinois’s own amount and duration rules (750 ILCS 5/504) set how much is paid each month and for how long, and that monthly stream is the thing being bought out.

Why is one payment today worth less than adding up every future check? Because money in hand now can sit in a safe account and earn interest over the same years those checks would have arrived. This alimony buyout calculator shows the same payment stream at 3.5%, 4.5% and 6.0% — the higher the rate, the smaller today’s lump sum, and the wider the gap between “paid monthly” and “paid up front”. Taking the deal up front means accepting a lump sum spousal support payment today instead of years of monthly checks.

In the 12-year, $120,000 payer / $40,000 recipient scenario used above, the monthly checks add up to $129,000 over 86 months — but settled as one single payment today they are worth $110,091 at 4.5%, $113,947 at 3.5% or $104,638 at 6.0%. That difference is what a settlement is really negotiating: the payer pays less in total, and the recipient gets the money sooner.

After the estimated $1,500-per-month transfer, the payer keeps about $6,000 per month (60% of the combined post-transfer total) and the recipient has about $4,000 (40%). The question after support is the simple one: what does each household actually have left to live on? The take-home split shows both sides after estimated taxes and after the payment, and since 2019 alimony is neither taxable for the receiver nor deductible for the payer, every dollar moves across unchanged. Print the calculator above as a spousal support worksheet and the inputs, the step-by-step math and these settlement figures all come out together on one clean page.