Illinois Alimony Calculator
Estimate spousal support in Illinois, where statutory formula decides the award. Includes likelihood, a modeled amount range, duration, and the statutory factors that decide what a court awards.
Last updated: Illinois cost figures are our own estimates, not independently verified
Illinois divorces typically cost 28% less than the national average of $12,900.
Alimony in Illinois
- How Illinois decides it
- Statutory formula
- What our estimate is
- Statutory term, modeled amount
- Fault considered
- No
- Domestic violence factor, in our record
- No
- Equal parenting presumption, in our record
- No
- Waiting period before final
- No statutory waiting period
Illinois's own term where its guideline reaches the case, our own amount. Illinois is the one state on this site whose own maintenance calculation we have read. We have read 750 ILCS 5/504, the maintenance section of the Illinois Marriage and Dissolution of Marriage Act: it was served by ilga.gov and retrieved 2026-07-30, and the section carries its own public act line, (Source: P.A. 103-967, eff. 1-1-25.), so it states what it is current through in its own text. P.A. 104-340, effective 8-15-25, was checked separately and amends the definition of "child" in § 505 rather than § 504. It changes one of the two figures on this page and not the other. Where the guideline route reaches a case, the TERM is calculated the way the statute calculates it, from the length of the marriage. The MONTHLY AMOUNT is still ours: the statute works that out from net annual income and this calculator collects gross, so the dollars are our national approximation, 30 percent of the difference between the two incomes, scaled by a factor for the length of the marriage. Each result below says which of the two you are looking at on your own entries.
Our record classifies Illinois as one of the small group of states that write a spousal support formula into the statute itself, and Illinois is the one state on this site whose formula we have actually opened. We have read 750 ILCS 5/504, the maintenance section of the Illinois Marriage and Dissolution of Marriage Act: it was served by ilga.gov and retrieved 2026-07-30, and the section carries its own public act line, (Source: P.A. 103-967, eff. 1-1-25.), so it states what it is current through in its own text. P.A. 104-340, effective 8-15-25, was checked separately and amends the definition of "child" in § 505 rather than § 504. What that buys you is the TERM. Where the guideline route reaches a case, the duration on this page is calculated the way the statute calculates it, on the length of the marriage, with nothing of ours inside it. What it does not buy you is the amount, and this estimate is not that formula: the statute's amount calculation runs on net annual income, this calculator collects gross, and we would rather give you the statute's own terms to run on your real figures than print our arithmetic under Illinois's name. Where the two differ, the statute is right and we are not.
Alimony Calculator in Illinois: What You Should Know
Illinois is the one state on this site whose own maintenance calculation we have read. 750 ILCS 5/504 sets out both halves of a guideline award, and they are different problems for us. Duration first, because it is the half this page now computes exactly. Section 504(b-1)(1)(B) multiplies the length of the marriage by a factor the statute fixes for each year of it: .20 below five years, .24 at five, and .04 more for every year after that up to .80 at nineteen. At twenty years or more the multiplier stops and the court orders either a term equal to the marriage or an indefinite one, in its discretion. The calculator on this page runs that ladder rather than a model of ours, and it measures the marriage at the time the case was commenced, which is what the statute says. Amount second. Section 504(b-1)(1)(A) takes 33 1/3 percent of the paying spouse's net annual income, subtracts 25 percent of the receiving spouse's net annual income, and then caps the result so that the receiving spouse's own net plus the award is not more than 40 percent of the two net incomes combined. We do not run that calculation, and the reason is the input rather than the arithmetic: it works from net annual income as section 505 defines it, and this calculator asks for gross. So the monthly figure here is still our own national model and the panel below gives you the statute's terms to run on your real figures. Two conditions decide whether any of this reaches your case, and the second is easy to miss: the guideline route needs combined gross annual income under $500,000, and it needs the paying spouse to have no support obligation from a prior relationship. Fail either and an Illinois court sets both the amount and the term on the statutory factors instead.
Key point: Illinois fixes the length of guideline maintenance by arithmetic, not by bands: the length of the marriage times a multiplier that rises with every year of it, from .20 under five years to .80 at nineteen, and an open-ended term at twenty. The duration on this page is that calculation. The dollar figure is not, because the statute works the amount out from net income and this calculator collects gross.
Tell us the basics
Locked to Illinois on this page.
Use your gross (before-tax) annual income.
Use their gross (before-tax) annual income.
This estimate is for planning purposes only and does not constitute legal or financial advice. Consult a licensed family law attorney in your state for guidance specific to your situation.
How Illinois awards spousal support
Our Illinois record classifies it as a statutory formula state, which means the legislature has written an arithmetic starting point into the statute, so two cases with similar incomes and a similar marriage length should land in a similar place. Here is what that looks like in practice.
Illinois's own term where its guideline reaches the case, our own amount
Illinois is the one state on this site whose own maintenance calculation we have read. We have read 750 ILCS 5/504, the maintenance section of the Illinois Marriage and Dissolution of Marriage Act: it was served by ilga.gov and retrieved 2026-07-30, and the section carries its own public act line, (Source: P.A. 103-967, eff. 1-1-25.), so it states what it is current through in its own text. P.A. 104-340, effective 8-15-25, was checked separately and amends the definition of "child" in § 505 rather than § 504. It changes one of the two figures on this page and not the other. Where the guideline route reaches a case, the TERM is calculated the way the statute calculates it, from the length of the marriage. The MONTHLY AMOUNT is still ours: the statute works that out from net annual income and this calculator collects gross, so the dollars are our national approximation, 30 percent of the difference between the two incomes, scaled by a factor for the length of the marriage. Each result below says which of the two you are looking at on your own entries.
Our record classifies Illinois as one of the small group of states that write a spousal support formula into the statute itself, and Illinois is the one state on this site whose formula we have actually opened. We have read 750 ILCS 5/504, the maintenance section of the Illinois Marriage and Dissolution of Marriage Act: it was served by ilga.gov and retrieved 2026-07-30, and the section carries its own public act line, (Source: P.A. 103-967, eff. 1-1-25.), so it states what it is current through in its own text. P.A. 104-340, effective 8-15-25, was checked separately and amends the definition of "child" in § 505 rather than § 504. What that buys you is the TERM. Where the guideline route reaches a case, the duration on this page is calculated the way the statute calculates it, on the length of the marriage, with nothing of ours inside it. What it does not buy you is the amount, and this estimate is not that formula: the statute's amount calculation runs on net annual income, this calculator collects gross, and we would rather give you the statute's own terms to run on your real figures than print our arithmetic under Illinois's name. Where the two differ, the statute is right and we are not.
A formula state gives the court a calculation to run rather than a list of considerations to weigh. The arithmetic works off the gap between the two incomes, not off either income on its own, which is why a raise for the lower-earning spouse cuts the award as surely as a pay cut for the higher earner does. Close the gap and the figure falls, even when neither household is worse off in total.
The formula is a starting point rather than a ceiling or a floor. A judge can depart from it, and departing generally means putting a reason on the record. That is what makes support in a formula state worth planning around in a way it is not elsewhere. What it does not mean is that every figure on this page is that formula. We have read one state's maintenance statute, Illinois', and there the duration is the statute's own arithmetic while the amount is still ours. Everywhere else both figures are a national approximation applied the same way in all fifty states. The panel above the calculator says which of the two you are looking at, beside every number it returns.
Length of marriage enters twice. It scales the amount, and separately it sets how long payments run. That second effect is the one people underestimate: the difference between a nine-year marriage and an eleven-year marriage is often larger in total dollars than a sizable difference in income would be.
One caveat matters more here than anywhere else on this page. Several states run a formula for temporary support while the case is open and then hand post-judgment support back to the court to decide on the statutory factors. Where that is how the state works, the arithmetic is a good guide to what gets paid during the case and a weaker guide to what gets ordered at the end of it. Check which of the two you are looking at before you plan around the number.
What Illinoiscourts weigh, in our data's order
These are the 3 factors our Illinois record carries, listed in the order it records them. They are the ground a support argument is actually fought on, so the side that documents them is the side arguing where the statute points.
- Length of the marriageThe strongest single predictor of both how much support is awarded and how long it runs. Short marriages point toward limited, time-boxed support aimed at getting the lower earner back on their feet. Long marriages point toward larger awards over longer terms, and are where indefinite support is still argued for.
- The income difference between the spousesThe figure the calculation is applied to. What matters is the gap, not either income by itself, so a rise in the lower earner's income reduces support just as a fall in the higher earner's does. Two couples with the same household total can reach very different results depending on how that total is split.
- Standard of living during the marriageThe benchmark the court measures need against. It is why the same income gap supports a larger award for a couple who lived expensively than for a couple who saved. Documenting how the household actually spent, through statements rather than recollection, is what makes this factor usable in a hearing.
Does conduct matter in Illinois?
No, and here we can point at the statute rather than at our own records. 750 ILCS 5/504(a) has the court determine maintenance "without regard to marital misconduct". Everywhere else on this site that answer comes from our factor list, which is a claim about what we hold rather than about what the legislature wrote. In Illinois it is the legislature. Evidence of an affair or of who left first has no purchase on the support question, and the same money spent documenting the marital standard of living or a career interrupted for the household does far more work.
Grounds are a separate question from support, and the two do not always line up. Our record has Illinois offering no-fault grounds only, our own record rather than Illinois's own law on divorce grounds, so on our record there is no fault ground to plead in the petition. Conduct is also absent from the support factor list, so for practical purposes who did what is not the argument that decides this case.
Support and the property split are one conversation
Our record has Illinois dividing marital property by equitable distribution, which means the split starts near even and moves with the same kinds of factors that drive support: length of marriage, each spouse's earning capacity, and what each contributed. That is our own record rather than Illinois's own property division law. Because the two questions run on overlapping facts, they are usually negotiated together. Trading a larger share of the estate for a smaller or shorter support award is one of the most common settlement structures there is, and it is often the one that gets a case resolved. Real outcomes in a formula state are less spread out than under open discretion, so a planning band means more here than it does elsewhere. That is a fact about the state rather than about this figure. Unless the panel above says otherwise, the estimate is the same national approximation every state on this site gets. A judge can depart from the statutory result anyway, and most support terms are settled by agreement rather than decided at a hearing.
One practical cost sits underneath that trade. Where the asset being swapped for support is a retirement account, dividing it takes a qualified domestic relations order, which runs $600 to $2,000 in Illinois on top of whatever else the case costs. Worth pricing in before you agree to take retirement money instead of monthly support, along with the fact that the two are taxed very differently when you eventually draw on them.
Illinois spousal support examples
These three examples run through the same Illinois calculator on this page, so the figures match what the tool returns for the same entries. Each is a different shape of case rather than a small variation on the one before, because the two things that move support most, the income gap and the length of the marriage, tend to move together in real households.
Read the range, not the middle figure. We draw the band comparatively narrow here, because a formula leaves less room between the high and low outcomes than open discretion does. The width is our judgement about that spread rather than anything the state publishes. In the second example below, the top of the band is about 1.3 times the typical figure.
Example 1: Four-year marriage, modest standard of living
A short marriage with a real but moderate income gap and no caregiving history. This is the case where support is most often brief or refused outright.
- Higher earner
- $85,000/yr
- Lower earner
- $38,000/yr
- Marriage length
- 4 years
- Likelihood
- Possible
Estimated range: $573 to $955 a month, typically around $764 ($9,168 a year), running 10 months.
Short marriages in Illinois may result in limited rehabilitative alimony. The term above is Illinois's own, calculated the way its maintenance statute calculates it, so on that axis this is not an estimate at all. The monthly amount is a different matter: it is our national approximation, because the statute works the amount out from a net income figure this calculator does not collect. A judge can also depart from the guideline, and most support terms are settled by agreement rather than decided at a hearing.
- The two employment statuses you entered have not changed the estimate above. You had to answer to get here, and whichever answer you picked the figure is the same: we calculate on the income figures you entered and impute nothing to either parent. Courts can impute. Where a judge finds a parent voluntarily unemployed or under-employed, a court may set support on what that parent could earn rather than on what they currently bring in, and an imputed figure is set at or above actual earnings rather than below them. Which way that would move your case depends on whose income gets imputed, and that is the part we cannot answer for you: if it is the paying party's, the figure above tends to sit below what a court would order, and if it is the receiving party's it can move in either direction depending on the state and on the two incomes, so we do not put a direction on it. We have read the imputation provision in Illinois and in no other state, Illinois included, so nothing on this page is adjusted for one.
- Whether the paying spouse has business income has not changed the estimate above. We ask because it shapes the case rather than the arithmetic: business income is the single most argued-about number in a support case, because what a business pays its owner and what a court treats as that owner's income are frequently different figures, and establishing the second usually takes disclosure or a forensic accountant. Nothing in the figures on this page is adjusted for your answer, so do not read the estimate as having priced it in.
Example 2: Twelve-year marriage, one spouse the primary caregiver
The most common shape of a contested support case: long enough that a career was reshaped around the household, not long enough to reach the territory where indefinite support gets argued.
- Higher earner
- $120,000/yr
- Lower earner
- $45,000/yr
- Marriage length
- 12 years
- Likelihood
- Likely
Estimated range: $1,406 to $2,344 a month, typically around $1,875 ($22,500 a year), running 6.3 years (75 months).
| Factor | Effect |
|---|---|
| Primary caregiver for children | Pushes up |
Medium-length marriages with a significant income gap frequently result in temporary alimony in Illinois. The term above is Illinois's own, calculated the way its maintenance statute calculates it, so on that axis this is not an estimate at all. The monthly amount is a different matter: it is our national approximation, because the statute works the amount out from a net income figure this calculator does not collect. A judge can also depart from the guideline, and most support terms are settled by agreement rather than decided at a hearing.
- The two employment statuses you entered have not changed the estimate above. You had to answer to get here, and whichever answer you picked the figure is the same: we calculate on the income figures you entered and impute nothing to either parent. Courts can impute. Where a judge finds a parent voluntarily unemployed or under-employed, a court may set support on what that parent could earn rather than on what they currently bring in, and an imputed figure is set at or above actual earnings rather than below them. Which way that would move your case depends on whose income gets imputed, and that is the part we cannot answer for you: if it is the paying party's, the figure above tends to sit below what a court would order, and if it is the receiving party's it can move in either direction depending on the state and on the two incomes, so we do not put a direction on it. We have read the imputation provision in Illinois and in no other state, Illinois included, so nothing on this page is adjusted for one.
- Whether the paying spouse has business income has not changed the estimate above. We ask because it shapes the case rather than the arithmetic: business income is the single most argued-about number in a support case, because what a business pays its owner and what a court treats as that owner's income are frequently different figures, and establishing the second usually takes disclosure or a forensic accountant. Nothing in the figures on this page is adjusted for your answer, so do not read the estimate as having priced it in.
Example 3: Twenty-four-year marriage, high standard of living, health limits
A long marriage, a wide income gap, and a documented health issue limiting the recipient's return to work. This is the combination that produces the largest and longest awards.
- Higher earner
- $185,000/yr
- Lower earner
- $30,000/yr
- Marriage length
- 24 years
- Likelihood
- Very likely
Estimated range: $4,069 to $6,781 a month, typically around $5,425 ($65,100 a year), running 24 years, the length of the marriage, or an indefinite term.
| Factor | Effect |
|---|---|
| Long marriage (20+ years) | Pushes up |
| Age or health limitations | Pushes up |
Long marriages with an income gap often result in extended or permanent alimony in Illinois. The term above is Illinois's own, calculated the way its maintenance statute calculates it, so on that axis this is not an estimate at all. The monthly amount is a different matter: it is our national approximation, because the statute works the amount out from a net income figure this calculator does not collect. A judge can also depart from the guideline, and most support terms are settled by agreement rather than decided at a hearing.
- Marriages of 20+ years may result in indefinite or permanent alimony in Illinois.
- The two employment statuses you entered have not changed the estimate above. You had to answer to get here, and whichever answer you picked the figure is the same: we calculate on the income figures you entered and impute nothing to either parent. Courts can impute. Where a judge finds a parent voluntarily unemployed or under-employed, a court may set support on what that parent could earn rather than on what they currently bring in, and an imputed figure is set at or above actual earnings rather than below them. Which way that would move your case depends on whose income gets imputed, and that is the part we cannot answer for you: if it is the paying party's, the figure above tends to sit below what a court would order, and if it is the receiving party's it can move in either direction depending on the state and on the two incomes, so we do not put a direction on it. We have read the imputation provision in Illinois and in no other state, Illinois included, so nothing on this page is adjusted for one.
- Whether the paying spouse has business income has not changed the estimate above. We ask because it shapes the case rather than the arithmetic: business income is the single most argued-about number in a support case, because what a business pays its owner and what a court treats as that owner's income are frequently different figures, and establishing the second usually takes disclosure or a forensic accountant. Nothing in the figures on this page is adjusted for your answer, so do not read the estimate as having priced it in.
Set the first and third examples side by side and the scale of what marriage length does becomes clear. The estimate moves from around $764 a month running 10 months to around $5,425 a month running 24 years, the length of the marriage, or an indefinite term. Part of that is the wider income gap. Most of it is the twenty extra years.
The panel below is worked out on the second example above: a twelve-year marriage, $120,000 and $45,000 a year. Enter your own figures in the calculator at the top of this page and it runs the same statute against them.
What Illinois's own statute calculates
The term above is Illinois' own, read out of 750 ILCS 5/504(b-1)(1)(B). The statute multiplies the length of the marriage by a factor fixed for each year of it. Your marriage falls in the band it states as "12 years or more but less than 13 years (.52)", and applying that factor gives 6.3 years (75 months). One thing to check against your own case: the statute measures the marriage at the time the action was commenced rather than as of today. The monthly amount beside it is not Illinois'. Section 504(b-1)(1)(A) calculates that from net annual income and this calculator collects gross, so the dollar figure is still our own national model, and the panel below gives the statute's own terms for you to run on your real net figures. On the guideline threshold we could measure a combined gross income of $165,000 a year, against the $500,000 the statute sets as the top of the guideline route. Note which income the threshold runs on: it is measured on combined GROSS, and the amount calculation inside it runs on net. Three further conditions decide whether the guideline reaches your case at all, and we can see none of them. The guideline route also requires that the paying spouse has no obligation to pay child support or maintenance, or both, from a prior relationship. We do not ask about that, and a spouse who has one is outside the guideline however far under $500,000 the two incomes are. A court may find that applying the guidelines would be inappropriate, in which case it sets maintenance under the non-guideline provision instead. That is a finding on the evidence and nothing in this calculator predicts it. Where guideline maintenance and child support together would exceed 50 percent of the paying spouse's net income, the court may set either or both outside the guideline. That test needs a child support figure and a net income, and this calculator collects neither.
Duration: the statute's own calculation
6.3 years (75 months)
The band your marriage falls in, in the statute's words: 12 years or more but less than 13 years (.52). The length of the marriage multiplied by 0.52.
This is the term shown above
A combined gross income of $165,000 a year, against the $500,000 the statute sets as the top of the guideline route. Note which income the threshold runs on: it is measured on combined GROSS, and the amount calculation inside it runs on net.
Amount: the statute's own calculation, which we do not run
Not applied, because it runs on net annual income, and this calculator collects gross
This is the calculation an Illinois court runs, quoted from the statute, and it is not the calculation behind the monthly figure on this page. The reason is the input rather than the arithmetic. Section 504(b-1)(1)(A) works from net annual income, and section 504(b-3.5) says net income here means what it means in section 505, so it is a defined figure rather than your take-home pay. This calculator asks for gross. Running the statute's percentages on gross would not be Illinois' calculation with a caveat attached, it would be a different calculation that comes out high in every case. Illinois does publish a gross to net conversion table, and we use it on the child support side of this site, but it is built for child support: it has two columns depending on which parent claims the dependency exemptions, this form never establishes that, and the two net figures enter the maintenance formula with opposite signs, so guessing the column pushes the answer up in some cases and down in others rather than in one direction you could correct for. The table also stops at $30,024.99 of monthly gross, roughly $360,300 a year, while the guideline route reaches couples up to $500,000 combined, so it runs out precisely where the largest guideline awards are. We would rather give you the statute's own terms and let you or an Illinois family law attorney run them on your real net figures than print a number with Illinois' name on it and our arithmetic inside.
“The amount of maintenance under this paragraph (1) shall be calculated by taking 33 1/3% of the payor's net annual income minus 25% of the payee's net annual income. The amount calculated as maintenance, however, when added to the net income of the payee, shall not result in the payee receiving an amount that is in excess of 40% of the combined net income of the parties.”
What we could not check
- The guideline route also requires that the paying spouse has no obligation to pay child support or maintenance, or both, from a prior relationship. We do not ask about that, and a spouse who has one is outside the guideline however far under $500,000 the two incomes are.
- A court may find that applying the guidelines would be inappropriate, in which case it sets maintenance under the non-guideline provision instead. That is a finding on the evidence and nothing in this calculator predicts it.
- Where guideline maintenance and child support together would exceed 50 percent of the paying spouse's net income, the court may set either or both outside the guideline. That test needs a child support figure and a net income, and this calculator collects neither.
Read from the statute. 750 ILCS 5/504, the maintenance section of the Illinois Marriage and Dissolution of Marriage Act, served by ilga.gov and retrieved 2026-07-30. On currency: the section carries its own public act line, (Source: P.A. 103-967, eff. 1-1-25.), so it states what it is current through in its own text. P.A. 104-340, effective 8-15-25, was checked separately and amends the definition of "child" in § 505 rather than § 504.
One caveat about how we hold it: rendered by a browser research session on an egress path this repo does not have, so nothing here can be re-checked from this environment. That is the same class of retrieval Phase AV rejected for the Texas Family Code; what separates them is that this section prints its own public act line and the Texas chapter printed no currency signal at all. The anchors in tests/calculators/illinois-alimony-formula.test.ts are what gate a regeneration.
How long spousal support lasts in Illinois
Duration is the question people ask second and worry about first, and it is decided differently from amount. Amount answers what the lower earner needs and what the higher earner can pay. Duration answers a narrower question: how long it should reasonably take the lower earner to get where they can stand on their own, and whether that is realistically possible at all.
The table below runs one couple through the Illinois estimate at seven marriage lengths. Incomes are held at $110,000 and $40,000 a year with no children and no health limits, so the only thing changing between rows is how long the marriage lasted.
One column of that table is not an estimate. The terms below are calculated the way Illinois's own maintenance statute calculates them, from the length of the marriage, wherever the guideline route reaches the case. The monthly figures beside them are still ours: the statute works the amount out from a net income figure this calculator does not collect, and the panel above sets out its terms so you can run them on your own.
| Marriage length | Band | Typical monthly | Duration | Likelihood |
|---|---|---|---|---|
| 2 years | Very short marriage | $700 | 5 months | Unlikely |
| 5 years | Short marriage | $1,138 | 1.2 years (14 months) | Possible |
| 10 years | Mid-length marriage | $1,488 | 4.4 years (53 months) | Likely |
| 15 years | Long marriage | $1,750 | 9.6 years (115 months) | Very likely |
| 20 years | Long marriage, common statutory threshold | $2,100 | 20 years, the length of the marriage, or an indefinite term | Very likely |
| 25 years | Very long marriage | $2,450 | 25 years, the length of the marriage, or an indefinite term | Very likely |
| 30 years | Very long marriage, retirement in view | $2,800 | 30 years, the length of the marriage, or an indefinite term | Very likely |
Two things are worth reading off that table. The first is that a five-year marriage and a twenty-year marriage are not the same case with a different number attached: at five years the term is 1.2 years (14 months) and support is only possible, while at twenty years it is 20 years, the length of the marriage, or an indefinite term and is very likely. The second is that the duration column carries single figures rather than ranges, and that is the statute rather than false precision on our part: Illinois sets the term by arithmetic on the length of the marriage. The monthly column beside it is still a modeled band, and the likelihood rating is ours as well.
Support also ends on events, not only on dates. Across states the usual terminating events are the death of either spouse, the recipient remarrying, and in many places the recipient living with a new partner in a marriage-like arrangement. Retirement in good faith at a normal age is the other common ground for cutting support off or reducing it. Whether Illinois treats each of those the same way is a question for a licensed attorney there, and it is worth asking before you sign an agreement rather than after.
Support while the Illinois case is still running
Illinois imposes no statutory waiting period before a divorce can be finalized, but a contested case here runs about 1.2 years on average against 4 months when both spouses agree. You also need 3 months of residency in Illinois before you can file at all. That stretch of time is the reason temporary support exists. A court can order support early in the case, well before anything final is decided, so the lower-earning spouse is not left covering a separate household on one income for about 1.2 years while the rest gets sorted out. If money is tight now, asking for a temporary order is almost always faster than waiting for the judgment, and the months spent waiting are rarely made up afterwards.
Recent Illinois alimony legislation
Illinois Continues to Refine Maintenance Formula Application
Our record dates this to January 1, 2023
No statute or court rule took effect on this date. What is described here is how courts have been deciding, or a requirement that has not changed.
Illinois courts continued refining how the statutory maintenance formula applies in cases with higher combined incomes. The formula applies up to a defined combined gross income threshold, above which courts use discretion. Recent appellate decisions have clarified how factors such as marital standard of living and earning capacity factor into discretionary awards above the threshold.
Illinois couples with combined income near or above the statutory threshold should expect outcomes to depend more on judicial discretion. Documenting marital standard of living and each spouse's earning trajectory is increasingly important for predictable awards.
No document behind this change has been opened here. The link goes to Illinois's own site rather than to the instrument, so read the change itself as our record.
Illinois CourtsWhere that legislation sets a durational limit, the limit controls and our estimate does not model it. Read the duration column above as our general model, then check it against the rule in the source linked here.
The kinds of spousal support a court can order
Support is not one thing. States use different names for the categories below and not every state recognizes all of them, but the underlying purposes are consistent, and knowing which one is being discussed tells you what the argument is really about.
- Temporary support, while the case is open
- Ordered after filing and before judgment, purely to keep two households running while the case is decided. In Illinois that window matters more than people expect: a contested case averages about 1.2 years, so this is often the largest block of support anyone actually receives. It ends when the final judgment lands, and it does not commit the court to continuing at the same figure.
- Rehabilitative support
- Time-limited support tied to a plan: finishing a degree, renewing a license, completing a training program, or re-entering a field after years away. It is the most common outcome for short and mid-length marriages. Because it is tied to a plan, the strongest version of this request comes with the actual program, its length, and its cost rather than a general statement about needing time.
- Durational or term support
- A set number of years, usually pegged to the length of the marriage, without needing to be tied to a specific rehabilitation plan. This is the category most reform legislation over the past decade has been about, generally replacing open-ended awards with a term the statute caps.
- Indefinite or permanent support
- Support with no end date written into it, reserved for long marriages where the age, health, or work history of the lower earner means self-sufficiency is not a realistic outcome. Indefinite does not mean unchangeable: it stays modifiable on a substantial change in circumstances, and it generally ends on the usual terminating events.
Data pending verification. Our Illinois record does not list which of these categories Illinois recognizes by name or what it calls them, so the descriptions above are the general framework rather than an Illinois list. We would rather say that than name four Illinois categories we have not checked.
How spousal support is taxed
This changed in a way that still catches people out. Under the federal Tax Cuts and Jobs Act, for any divorce or separation agreement executed after December 31, 2018, alimony is not deductible by the spouse paying it and is not taxable income to the spouse receiving it. The federal rule is the same in Illinois as everywhere else, because it is federal.
Two consequences follow, and both are worth understanding before you negotiate. Support is now paid out of after-tax dollars, so a given monthly figure costs the payer considerably more than the same figure did before 2019. And the older advice that a large award could be made cheaper by the deduction no longer applies at all. Agreements executed on or before December 31, 2018 generally keep the old treatment, though modifying one can bring it under the current rule if the modification says so.
State income tax is a separate question from the federal one, and it is not something this page models. Check the federal treatment against the IRS guidance below, and check the Illinois treatment with a CPA or a licensed family law attorney in the state.
- IRS Topic No. 452, alimony and separate maintenance, the federal rule on deductibility and taxability.
What it costs to argue about support in Illinois
Support is the issue most likely to turn a divorce contested, and it is also the one where the arithmetic of fighting is easiest to get wrong. Below are the Illinois figures set against what is actually in dispute.
- Attorney rate
- $250 to $500/hr
- Mediation session
- $275
- Uncontested case
- $2,000 to $5,500
- Contested case
- $13,000 to $45,000
Put those next to the second worked example above, where the estimate came to $1,875 a month, or $22,500 a year. A contested case in Illinois runs $13,000 to $45,000, which is the equivalent of roughly 7 to 24 months of that support. Ten billable hours on each side, which a single contested motion can consume, costs $2,500 to $5,000 per side at Illinois rates. Two mediation sessions cost $550 shared between you.
The sharper way to read those figures is as a difference rather than a total. An uncontested Illinois divorce runs $2,000 to $5,500 and takes 4 months. Contesting it adds $11,000 to $39,500, or roughly 6 to 21 months of the support in that example, and stretches the case to about 1.2 years. That difference is the actual price of the argument, and it is the number to hold against whatever separates your position from your spouse's.
None of that means give up a position worth holding. Where the gap between the two sides is large, where one spouse's income is hard to pin down, or where the marriage was long enough that duration is the real question, representation earns its cost several times over. But where the two positions sit a few hundred dollars a month apart, the arithmetic usually says settle: the fight can cost more than the difference it is about. Our record does not have Illinois requiring mediation before a contested hearing, but at $275 a session against a contested case starting at $13,000, it is usually the cheapest serious attempt at a resolution available. That is our own record rather than Illinois's own court rules. Our record carries collaborative divorce as available in all fifty states, so it says nothing specific about Illinois; whether trained collaborative attorneys practise near you is a local question. Where it is on offer, both sides commit in writing to settle without litigation and share one financial expert instead of hiring two.
Illinois spousal support authority
The Illinois spousal support authority in our data is 750 ILCS 5/504 maintenance formula. That authority controls. The estimate on this page models how support is decided in Illinois, it does not reproduce the statutory text, and where the two differ the statute is right and we are not.
Where to check this yourself
- Illinois courts, the state judiciary site from our Illinois source record.
- American Bar Association, Section of Family Law, which publishes state-by-state family law comparisons.
- IRS Topic No. 452, alimony and separate maintenance, for the federal tax treatment described above.
Alimony in Illinois - Frequently Asked Questions
Does Illinois have an alimony formula?
Yes, and half of it is on this page. Illinois writes its maintenance calculation into the statute, and 750 ILCS 5/504, the maintenance section of the Illinois Marriage and Dissolution of Marriage Act is the one state alimony statute whose arithmetic this calculator runs. The duration figures on this page are that statute's arithmetic: the length of the marriage multiplied by a factor it fixes for each year of it, applied wherever the guideline route reaches the case. The monthly dollar figures are not. Illinois works the amount out from net annual income and this calculator collects gross, so the dollars are our own approximation and every panel that shows one says which of the two you are looking at. The authority in our data is 750 ILCS 5/504 maintenance formula.
How is spousal support calculated in Illinois?
By a calculation 750 ILCS 5/504, the maintenance section of the Illinois Marriage and Dissolution of Marriage Act sets out, and this page reproduces one half of it. The term is the length of the marriage multiplied by a factor the statute fixes for each year of it, and that is what the duration figures here are. The amount is 33 1/3 percent of the paying spouse's net annual income less 25 percent of the receiving spouse's, capped so the receiving spouse's own net plus the award stays under 40 percent of the two combined. We do not run that half: it works on net income and this calculator collects gross, so the dollars here are 30 percent of the difference between the two incomes, scaled by a factor for the length of the marriage. The statutory factors our Illinois record carries are length of the marriage, the income difference between the spouses, and standard of living during the marriage. Take the amount to a family law attorney licensed in Illinois with your real net figures.
How long does alimony last in Illinois?
By arithmetic, in Illinois, wherever the guideline route reaches the case. 750 ILCS 5/504, the maintenance section of the Illinois Marriage and Dissolution of Marriage Act multiplies the length of the marriage by a factor it fixes for each year of it, so a 10-year marriage runs 4.4 years (53 months) and a 20-year marriage reaches the branch where the court orders either 20 years, the length of the marriage, or an indefinite term. Those figures are the statute's rather than ours. Support also ends on events rather than only on dates: the death of either spouse, the recipient remarrying, and in many states the recipient cohabiting with a new partner.
How much alimony is typical in Illinois?
There is no single figure, because the answer depends on the gap between the two incomes and how long the marriage lasted. As a worked example, a 12-year Illinois marriage where one spouse earns $120,000 a year, the other earns $45,000, and the lower earner was the primary caregiver produces an estimate of $1,406 to $2,344 a month, typically around $1,875, running 6.3 years (75 months). The term above is Illinois's own, calculated the way its maintenance statute calculates it, so on that axis this is not an estimate at all. The monthly amount is a different matter: it is our national approximation, because the statute works the amount out from a net income figure this calculator does not collect. A judge can also depart from the guideline, and most support terms are settled by agreement rather than decided at a hearing. Run your own figures in the calculator on this page.
Can alimony be modified in Illinois?
Yes. Either spouse can ask the court to modify alimony based on a substantial change in circumstances, such as a significant change in income, retirement, the recipient's remarriage or cohabitation, or a serious health change. Illinois courts typically require the change to be material and not anticipated at the time of the original order.
Does fault affect alimony in Illinois?
No, and this is one of the few states where we can point at the words rather than at our own records. 750 ILCS 5/504(a) has the court determine maintenance "without regard to marital misconduct". Courts here work from need, ability to pay and the other statutory factors, so money spent proving who did what buys nothing on the support question.
Is alimony tax deductible in Illinois?
For divorces finalized after December 31, 2018, alimony is no longer deductible by the payer or taxable to the recipient under the federal Tax Cuts and Jobs Act. This federal rule applies in Illinois as it does in every state. Older orders entered before 2019 generally retain the prior tax treatment unless modified.
This estimate is for planning purposes only and does not constitute legal or financial advice. Consult a licensed family law attorney in your state for guidance specific to your situation.
How we calculate this estimate
Alimony is the least formula-driven number in a divorce, and outside one state this estimate is a national approximation rather than any state's own rule. It works from the gap between the two incomes, scaled by how long the marriage lasted, with the share of that gap set by how your state is recorded as deciding support and by the standard of living during the marriage. The other inputs, employment status on both sides, caregiving history, age and health, and marital fault where your state weighs it, move the factors and the likelihood rather than the arithmetic. The output is a monthly range with a duration range, a likelihood rating, and the specific factors pushing your case up or down.
What the estimate assumes for Illinois
- One state's own calculation is implemented, in half. Six states write a spousal support calculation into their own statute. We have read one of them, 750 ILCS 5/504, and the duration our Illinois calculator returns is that statute's arithmetic rather than our model's: the length of the marriage multiplied by a factor the statute fixes for each year of it, wherever the guideline route reaches the case. The Illinois AMOUNT is still ours, because the statute works it out from net annual income and this calculator collects gross. Everywhere else, both figures are the same national approximation. Every alimony figure we return says which of the two it is, beside it.
- The share of the income gap our estimate applies depends on which of three groups our record puts your state in, and the marriage-length factor then multiplies it in every case. A formula state takes 30 percent of the gap, which the factor moves to between 12 and 48 percent of it. A discretionary state takes between 22 and 38 percent depending on the standard of living during the marriage, moving to between 8.8 and 60.8 percent. A hybrid state averages the two, landing between 10.4 and 54.4 percent. Those are the figures before any ceiling a state sets, every one of them is ours, and no state publishes any of them.
- Duration is modeled at about a third of the length of the marriage, with a band around it and a cap at the length of the marriage, in forty-nine states. How wide that band runs depends on the same grouping: a formula or hybrid state gets 20 to 50 percent of the length of the marriage, a discretionary state 13.3 to 66.7 percent. Several of them set duration as a share of the marriage by statute and none of those shares is a third. Illinois is the exception: its ladder runs from .20 below five years to .80 at nineteen and opens up at twenty, we have read it, and our Illinois duration is that calculation rather than the model.
- State limits are applied in five states and shown without being applied in six more. Delaware, Florida, Kansas, Louisiana and Texas each set a ceiling on the amount or the term, we have read that ceiling out of the state's own instrument, and where our arithmetic ran past it the ceiling is what produced the figure. Florida, Louisiana and Texas are the ones whose ceilings are worked on a base the instrument does not use: their rules measure an income this page does not collect, so what we apply is a generous version of the state's own limit, which is why we are willing to bring a figure down to it and never up to it. Each of those pages says so beside the figure. Massachusetts and Maine's limits are rebuttable presumptions rather than ceilings, so they are shown beside the figure rather than applied to it. Massachusetts carries a second reason on top of that one, set out on its own page beside the figure, and it is the harder of the two: what the rule measures is not what this page collects. Indiana, New Hampshire, New Jersey and Utah have limits our own pages state and nobody here has opened the document behind, so those are worked out on your entries and set beside our estimate without changing it. We do not clamp a number to a figure we could not read. The other 39 states have no limit in our records, which is a statement about our records rather than about their law: where your state limits an amount or a term and we hold nothing for it, the limit still controls and this estimate can exceed it.
- Which of the three approaches a state takes came into our data at the original build. It has since been checked against the state's own rendered instrument in 4 states, Florida, Illinois, New York and Texas, and each of those pages names the instrument that settled it. In the other 46 it is still our record's classification with no statute behind it.
- Fault is only factored in for states where our record says fault can affect a support award.
- The one cost-table figure this page uses is your state's waiting period, and it is our own record rather than a reading of the statute. Nobody here has opened a dissolution statute to check the number, and the same field carries two different things across the fifty states, a wait that runs from filing and a separation requirement that runs from the day you separated. Confirm it with the clerk of court where you will file.
- The estimate is pre-tax. It does not model how support affects either spouse's tax return.
Where the estimate stops
Outside the Illinois duration, this is our model rather than your state's. In a state that publishes its own calculation the number to plan around is that calculation, and a family law attorney licensed there can run it on your figures. Even where a guideline applies, a judge can depart from it and most support terms are negotiated rather than tried, so treat the range as a planning band rather than a prediction of your order.
Read the full methodology for how every calculator on the site is built.
Sources
Illinois courts and statutes
- illinoiscourts.gov
- 750 ILCS 5/504 maintenance formula
- 750 ILCS 5/505
- 750 ILCS 5/505(a)(3.8)
- hfs.illinois.gov
- hfs.illinois.gov
- hfs.illinois.gov
Where to read more
Background reading, not where the figures above came from. No number on this page is taken from any of these.
About this page
Written by Barron Hansen
I am an app developer who is dedicated to building the highest-value, most accurate web apps possible, that people want to use every day.