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What is an Illinois prenup?
Everything to know about Illinois prenups.
Prenuptial agreements (sometimes called "premarital agreements" in Illinois) are contracts entered into before marriage between a couple. They outline things like property ownership, property division, alimony, taxes, pets, rings, and many other topics. Prenups can be emotional documents as much as they are practical ones. They help set expectations and boundaries for a couple prior to entering into marriage, which in turn can create a stronger foundation for the marriage.
Prenuptial agreements in Illinois are governed by 750 ILCS 10/1 et seq. and the relevant state case law that helps shape the laws around prenups. Below, everything you need to know, organized exactly the way an Illinois family law attorney would walk you through it.
The controlling statute & cases
What law governs prenups in Illinois?
Illinois prenups are governed by statute (750 ILCS 10/1 et seq.) and case law. The Illinois legislature and judiciary have made it clear that prenuptial agreements are enforceable in the state as long as they meet certain requirements set forth in the statutes and by court opinion. Some of these requirements include putting the agreement in writing and having signatures of both parties, financial disclosure, conscionability, and voluntariness.
Is Illinois a UPAA state?
Yes, Illinois is one of the 28 states, plus D.C., that have adopted a version of the Uniform Premarital Agreement Act (UPAA). It was adopted in 1990, a few short years after the UPAA was released. Illinois' version of the UPAA is largely the same as the model act, but adds an additional carve-out for courts to invalidate spousal support waivers for undue hardship. (750 ILCS 10/1 et seq.).
Requirements for an Illinois prenup
What are the requirements for a prenup in Illinois?
The requirements for an Illinois prenup are laid out in 750 ILCS 10/1 et seq. The statute mimics the UPAA model rule, which requires prenups to be in writing, signed, financial disclosure, and the parties must enter into the agreement voluntarily. In addition, the circumstances surrounding the prenup and the terms within must not be unconscionable. In addition, the agreement must only contain permissible subjects, such as property division. Courts in Illinois also retain discretion to invalidate spousal support waivers that create undue hardship.
Requirements:
- In writing
- Signed by both parties
- Fair and reasonable financial disclosure
- Entered into voluntarily
- Not unconscionable
- Contains only permissible subjects, such as property division
Does a prenup need to be notarized in Illinois?
No, prenups in Illinois do not need to be notarized; however, many Illinois attorneys recommend notarization anyway. Notarizing your prenup in Illinois adds an additional layer of protection, though it is not formally required. A notarized prenup shows a court that the parties actually signed the agreement and understood what they were signing was, in fact, a prenuptial agreement.
Do both parties need a lawyer for a prenup in Illinois?
No, you do not need a lawyer to create a valid prenup in Illinois. The prenup statute only requires it to be in writing, with signatures, and proper financial disclosure. Illinois courts have routinely upheld prenups where parties were unrepresented by counsel. For example, in Kranzler v. Kranzler, the court upheld a prenuptial agreement even though the wife argued she was under pressure, did not fully understand the agreement, and was pregnant at the time she signed it. Importantly, the court emphasized that she had the opportunity to consult with an attorney, review the agreement for several weeks, and seek legal advice before signing. The case supports the idea that having a lawyer in Illinois is not required for a valid prenup. (Kranzler v. Kranzler, 2018 IL App (1st) 171169, 116 N.E.3d 346).
What makes a prenup invalid in Illinois?
A prenup may be deemed invalid in Illinois for several reasons. First, it may be invalidated based on improper formalities, such as a verbal agreement (i.e., not in writing) or a lack of proper signatures. In addition, if one or both of the parties do not properly disclose their finances, it may be deemed unenforceable for improper financial disclosure. Additionally, if either party did not enter the agreement voluntarily, such as being coerced into signing the document, it may not be enforced. And, finally, if the agreement is unconscionable, it may be invalidated.
How long before the wedding should I sign a prenup in Illinois?
Illinois does not mandate a specific time before the wedding to sign the prenup. Illinois courts have consistently held that the timing of a prenuptial agreement's signing (by itself) does not invalidate the agreement. For example, in a case from 2025, Duda v. Duda, the court upheld a prenup even though there was a short time between the prenup signing and the wedding. The court explained that the parties married at City Hall with no evidence of substantial wedding expenses or disappointed guests, and stated that "while timing could be a factor, the [Illinois prenup] statute [does] not require a minimum waiting period." (Duda v. Duda, 2025 IL App (1st) 242448-U).
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Start your prenup for freeWhat can & can't be in an Illinois prenup
Does cheating void a prenup in Illinois?
No, cheating does not void a prenup in Illinois. Illinois is a "no-fault" divorce state, meaning divorce only requires that "irreconcilable differences have caused the irretrievable breakdown of the marriage" (750 ILCS 5/401). There is no category for adultery, meaning the act of infidelity or adultery doesn't constitute grounds for divorce, nor does it automatically invalidate a prenuptial agreement.
Are infidelity clauses enforceable in Illinois?
No, infidelity clauses are not enforceable, but you may be able to recoup funds that were spent on an affair during the marriage. According to Illinois prenup attorney Mathew Kerbis, "infidelity clauses are relics of a bygone era, and Illinois courts cannot punish a cheating spouse through property division or maintenance. However, you can try to recover marital funds spent on an affair, and a well-drafted prenup can account for this possibility."
Can a prenup include child custody in Illinois?
No, prenuptial agreements may not include child custody matters in Illinois. Child custody is a matter for the court to determine, based on the child's best interests, at the time of separation. (750 ILCS 5/602.5). It would be against the public policy of Illinois to allow two parents to pre-determine custody matters, potentially years before a custody dispute were to take place. Circumstances change, people change, and children's needs change. It could be harmful to uphold these terms, and therefore, is not permissible in the state.
Can a prenup protect a business in Illinois?
Yes, an Illinois prenup can protect business interests. A prenup that is meant to protect business interests in Illinois should ensure that any business income, appreciation, assets, equity, and/or debt is marked as separate property (i.e., "non-marital property"). Anything that is validly earmarked as "non-marital property" in an Illinois prenup is not divisible in a divorce. Without a prenup, it is possible that business interests can be divided between spouses.
Can a prenup protect inheritance in Illinois?
Yes, a prenup can protect inheritances in Illinois. By default, inheritances are technically considered non-marital property already (meaning not divisible in a divorce). (750 ILCS 5/503). However, if those inherited funds or property are commingled with other funds or marital funds are used to grow the inherited funds/property, they can become divisible in a divorce. (In re Marriage of Vondra, 2016 IL App (1st) 150793 (2016)). Utilizing a prenup to clarify that the intention is to keep the inherited funds/property separate, despite titling, contributions, etc., can help ensure that inheritance stays separate.
Marital property in Illinois
Is Illinois a community property state?
No, Illinois is not a community property state; it is an equitable distribution state. There are only nine community property states in the U.S., and the rest are considered equitable distribution. Illinois is one of them. Equitable distribution is a property division framework that allows judges discretion in dividing a divorcing couple's property, as opposed to community property principles, which automatically divide property acquired during marriage 50-50, with few exceptions.
How is property divided in a divorce in Illinois without a prenup?
Without a prenup, property in Illinois is divided first by categorizing all of the assets and debt as either marital property or non-marital property. If something is deemed "non-marital property," then it is not divisible in the divorce. If something is deemed "marital property," then it is divisible in a divorce. The court will also handle untangling any commingled property, which is when non-marital property gets mixed with marital property. Once that has been determined, the court will divide marital property in a way that it deems "just" based on a set of factors. Those factors include each spouse's contributions to the marriage (including homemaker responsibilities), length of the marriage, each spouse's age and health, and others. (750 ILCS 5/503).
What is separate property in Illinois?
In Illinois, "separate property" is called "non-marital property," but it means the same thing: any property that is only owned by one spouse, and is not divisible in a divorce. According to 750 ILCS 5/503, non-marital property includes property acquired before marriage, inherited property, the exchange of non-marital property for new property, and the growth of non-marital property (with right of reimbursement).
Alimony in Illinois
Can a prenup waive alimony in Illinois?
Yes, a prenup can waive alimony (also called "maintenance") in Illinois. However, Illinois' prenup statute has a carve-out in 750 ILCS 10/7 that says a judge has the right to invalidate an alimony waiver or modification if it would cause "undue hardship" upon that person. In other words, courts are allowed to modify alimony terms in a prenup if the court deems it to be unfair to the point of causing harm to one person.
Illinois' undue-hardship carve-out on alimony waivers
Unlike most UPAA states, Illinois added a statutory safety valve: under 750 ILCS 10/7, a court may modify or set aside a spousal-support waiver if enforcing it would leave one spouse in undue hardship due to circumstances that were not reasonably foreseeable when the prenup was signed.
The waiver is still valid and enforceable; this carve-out only gives a judge limited discretion to step in at the time of divorce. A clear, fully disclosed, voluntarily signed agreement is the best way to keep an Illinois alimony waiver intact.
Does a prenup prevent spousal support in Illinois?
Yes, a prenup can prevent spousal support (i.e., "maintenance") in Illinois, as long as the couple includes a waiver of such and it does not cause undue hardship upon the person waiving it. (750 ILCS 10/7). However, a prenup can only "prevent" spousal support if the prenup is drafted that way. A prenup is customized to each couple, so some couples may require alimony in their prenup, whereas other couples may want to prevent it.
How is alimony determined in Illinois without a prenup?
Alimony is called maintenance in Illinois and is determined by 750 ILCS 5/504. The statute explains that alimony is first determined by looking at factors such as length of marriage, each spouse's health, standard of living during the marriage, etc. If the court deems maintenance to be appropriate, then the court will apply a mathematical formula for couples with a combined annual income of $500,000 or less, and where the paying spouse doesn't already owe support from another relationship. The formula is 33.33% of the paying spouse's net annual income minus 25% of the receiving spouse's net annual income. However, the receiving spouse cannot get more than 40% of the parties' combined net income after maintenance is added. Duration of maintenance is also a calculation based on the number of years married.
How much does a prenup cost in Illinois?
How much does a prenup cost in Illinois?
According to Illinois prenup attorney Mathew Kerbis, "Paying a typical hourly attorney to help with a prenup could easily cost more than $2,000 for just one fiancee." The total for one couple could reach up to $4,000 or more, depending on the complexity of the finances, the requests, and the amount of time the lawyer spends negotiating with the other partner's attorney. With HelloPrenup, a prenup costs $599 flat. Add-on Illinois attorneys cost an additional $699 flat.
What is the cheapest way to get a prenup in Illinois?
Generally, the cheapest way to get an enforceable prenup in Illinois is to utilize a reputable online prenup platform that emphasizes state compliance. Some online prenup platforms, like HelloPrenup, offer additional, optional attorney-review add-ons. For example, HelloPrenup has Illinois-licensed attorneys available to review your online prenup to ensure that it's enforceable and meets your specific needs.
How much does a prenup lawyer cost in Illinois?
An attorney in Illinois charges an average of $350 per hour. This hourly rate can increase or decrease depending on the geographic area of the lawyer (Chicago vs. Effingham) and the accolades/experience of the attorney. Chicago prenup attorneys tend to charge above this rate, whereas small-town Illinois prenup attorneys charge less. The total cost for a prenup lawyer in Illinois not only depends on the attorney's hourly rate, but also on how many hours it takes for the attorney to work on your case. If there are complicated finances to sift through or back-and-forth negotiations, the hours will rack up, ultimately resulting in a higher prenup lawyer cost.
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Book a consultationHow to get a prenup in Illinois
How do I get a prenup in Illinois?
There are three main paths to getting an enforceable prenup in Illinois: (1) Hiring two local attorneys to draft and review your agreement; (2) Using a state-compliant online prenup; or (3) Using a hybrid of (1) and (2) and hiring a lawyer to review your online prenup. All three options are great ways to create a valid and enforceable prenup in Illinois. The only caveat is to ensure the online prenup you use is reputable and complies with Illinois state law.
Can I write my own prenup in Illinois?
Technically, yes, you can write your own prenup in Illinois and have it hold up in court. However, it is incredibly risky and has higher chances of being thrown out than if it were done by attorneys or a reputable online prenup platform. Courts do not require parties to hire lawyers for a prenup in Illinois, but there are other requirements that must be met, which may be difficult to understand without legal help. For example, there must be "fair and reasonable" financial disclosure, which may be difficult to achieve without the advice of counsel. A lack of proper financial disclosure can get the prenup thrown out.
How long does it take to get a prenup in Illinois?
It depends on each fiance's commitment to the prenup process. And, if the parties are hiring lawyers, the availability and speed of the prenup lawyer. For example, some prenup attorneys may take a few hours to draft a prenup, whereas others may take a few weeks. This variance may be due to client requests, the attorney's case load, and the attorney's experience. With HelloPrenup, it is possible to generate an Illinois prenup in two hours. If you want to add on Illinois-licensed attorney help, the time may increase to a few days, again, depending on the attorney's availability.
Do I need a lawyer to get a prenup in Illinois?
No, you do not need a lawyer to get a prenup in Illinois, though it is highly recommended and can help your agreement hold up in court. Not only do lawyers help ensure you have met the specific state requirements for a valid prenup, such as proper financial disclosure, but the presence of legal counsel can help deter arguments of coercion or duress. When parties have been explained their rights, received legal advice, and participated in negotiations for the prenup, it's harder to argue that they signed the agreement involuntarily.
Caselaw & enforceability
Are prenups enforceable in Illinois?
Yes, prenups are enforceable in Illinois. The Illinois legislature has favored the use of prenups since 1990, when it enacted a version of the UPAA to give practitioners and couples instructions on exactly how to create a valid and enforceable prenup. (750 ILCS 10/1 et seq.) In addition, Illinois courts also favor the use of prenups as public policy and are presumed valid unless a party brings specific grounds for unenforceability. (In re Marriage of Amyette, 2023 IL App (3d) 200195 (2023)).
How hard is it to break a prenup in Illinois?
It is difficult to break a prenup that was executed properly according to state law. If a prenup was put in writing, signed, included proper financial disclosure, was entered into voluntarily, and is not unconscionable, then it will be upheld in Illinois. A party challenging the agreement needs to bring a valid legal reason to court in order to "break" the prenup.
Can a judge throw out a prenup in Illinois?
Yes, it is possible for a judge in Illinois to throw out a prenuptial agreement, as long as it is a valid legal reason under the Illinois Premarital Agreement Act (750 ILCS 10/1 et seq.) or other relevant case law or policy. For example, an Illinois court threw out a postnuptial agreement in 2014 (even though it's a postnup, similar principles apply to prenups). The court explained that the postnup was unconscionable due to requiring the wife to forfeit all rights to her home if she "unreasonably" filed for divorce, but this penalty did not apply to the husband. In addition, the vagueness of "unreasonable divorce" made it difficult to enforce, especially because it required a therapist's determination of "unreasonable." (In re Marriage of Iqbal and Khan, 2014 IL App (2d) 131306 (2014)).
What can void a prenup in Illinois?
A prenup in Illinois can be voided by improper formalities under the Illinois Premarital Agreement Act, such as a lack of signatures. It can also be voided through lack of fair and reasonable financial disclosure, involuntariness, or unconscionability. Involuntariness includes duress, oppression, undue influence, or taking undue advantage of the stress of another to the point where another is deprived of the exercise of free will. (In re Marriage of Prill, 2021 IL App (1st) 200516 (2021)). Unconscionability means grossly unfair results from enforcing the prenuptial agreement. (In re Marriage of Iqbal and Khan, 2014 IL App (2d) 131306 (2014)).
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Start your prenup for freeDuration & after-marriage
How long does a prenup last in Illinois?
A prenup lasts forever in Illinois, unless otherwise specified in the prenup itself. For example, couples may include what's known as a "sunset clause" that effectively places an expiration date on the prenup (or "sunsets" the agreement). Some couples choose to sunset an agreement on a certain wedding anniversary, such as their 20th anniversary (but couples can choose whatever date makes sense for them). Couples may choose to include a sunset clause because they believe the marriage will have been so long at this point that assets are so mixed that it would be inequitable to keep certain assets separate or waive spousal support.
Can you get a prenup after marriage in Illinois?
No, you cannot get a "prenup" after marriage, but you can get a postnuptial agreement ("postnup"). Prenups are only valid if signed before marriage. If the wedding day has already passed, parties can get a postnuptial agreement in Illinois. A postnup in Illinois is valid under 750 ILCS 5/503(a)(4), "marital property" excludes "property excluded by valid agreement of the parties, including a premarital agreement or a postnuptial agreement." In other words, the Illinois legislature has expressly permitted the use of postnuptial agreements in determining property division in a divorce.
Postnups in Illinois have an additional requirement that is different from prenups, and that is "consideration." Postnups in Illinois require legal consideration, which simply means that the parties must exchange something of value with one another in order to make the agreement valid. (In re Marriage of Labuz, 2016 IL App (3d) 140990 (2016)). With prenups, the agreement to get married is enough "consideration" to effectuate the agreement.
Can you change a prenup in Illinois?
Yes, you may change (i.e., "amend") a prenup in Illinois under 750 ILCS 10/6, as long as it is in writing and follows the other rules laid out by the statute for the original agreement. Couples may want to change a prenup due to an increase or decrease in financials or lifestyle, and the agreement may no longer reflect their true intentions.
Cross-border & recognition
Is a prenup signed in another state valid in Illinois?
Generally, yes, as long as it was executed properly in the original state and doesn't violate any Illinois laws or policies. Under general contract law, Illinois recognizes and honors choice of law provisions in regular contracts. (United Nuclear Corp. v. Energy Conversion Devices, Inc., 110 Ill.App.3d 88 (1982)). In application to prenups, Illinois courts may enforce an out-of-state choice of law clause applying substantive law, as long as not in any violation of Illinois law.
What happens to my Illinois prenup if I move to another state?
Most states enforce prenups created in foreign states, as long as they followed the rules of creation in the original state. However, whether or not the new state applies substantive law (i.e., the base law that defines the terms of the agreement) depends on each state's laws. For example, a state may enforce the prenup in general based on the original state's execution and enforcement laws, but apply its own laws when interpreting terms within the agreement, such as how spousal support is dispersed (if not already defined).
Illinois caselaw
Important prenup case law in Illinois
Six Illinois decisions that shape how courts evaluate prenuptial agreements. Click any case for the full opinion.
IL App (1st) · 2018
Kranzler v. Kranzler
2018 IL App (1st) 171169, 116 N.E.3d 346
The court upheld a prenup even though the wife argued she was pressured, did not fully understand it, and was pregnant when she signed. What mattered was that she had the opportunity to consult an attorney and review the agreement. Confirms a lawyer is not required for a valid Illinois prenup.
IL App (1st) · 2025
Duda v. Duda
2025 IL App (1st) 242448-U
The court upheld a prenup despite a short window between signing and the wedding, noting the couple married at City Hall with no substantial wedding expenses. The Illinois statute does not require a minimum waiting period before signing.
IL App (2d) · 2014
In re Marriage of Iqbal and Khan
2014 IL App (2d) 131306
An Illinois court struck down an agreement as unconscionable: it forced the wife to forfeit her home rights for an "unreasonable" divorce while imposing no equivalent penalty on the husband, and the vague standard was unenforceable. The leading Illinois case on unconscionability.
IL App (1st) · 2021
In re Marriage of Prill
2021 IL App (1st) 200516
Defines involuntariness in the Illinois prenup context: duress, oppression, undue influence, or taking undue advantage of another's stress to the point of depriving them of free will. A key reference for what makes a signing "voluntary."
IL App (1st) · 2016
In re Marriage of Vondra
2016 IL App (1st) 150793
Illustrates how non-marital inheritance can become divisible once it is commingled with marital funds. Shows why a prenup is the cleanest way to keep inherited property separate regardless of titling or contributions.
IL App (3d) · 2023
In re Marriage of Amyette
2023 IL App (3d) 200195
Reaffirms that Illinois courts favor prenuptial agreements as a matter of public policy and presume them valid unless a challenging party brings specific grounds for unenforceability.
How it works
Easy, all-in-one solution designed to
complete an enforceable agreement in about a day
Step 1
Fill out your questionnaires
Both you and your partner will fill out your own Illinois-specific questionnaires on your own HelloPrenup accounts. The questions cover separate property, gifts & inheritance, debts, pets, businesses, and the issues that matter under Illinois law, like fair and reasonable financial disclosure.
Step 2
Align on clauses together
Compare answers with your partner and align on differences to build your custom Illinois clauses together. Negotiate openly without back-and-forth attorney emails.
Step 3 (optional)
Review with an Illinois attorney
Under Illinois law, lawyers are not required for a valid Illinois prenup, but adding independent counsel is one of the strongest enforceability levers in Illinois. Add an Illinois attorney directly in your account for $699 flat, per partner. That's far below the $4,000 or more a traditional Illinois prenup can cost.
Step 4
Review & notarize your prenup
Review your completed Illinois prenup and notarize it easily online through our partner, Proof. Notarization isn't strictly required in Illinois, but it's strongly recommended and standard practice. Two witnesses are provided as needed for Illinois agreements that waive estate rights.
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HelloPrenup has partnered with over 100 elite attorneys across the country, including Illinois-licensed family lawyers. Every attorney meets our strict standards for quality services.
Under Illinois law, lawyers are not required for a valid Illinois prenup, but independent counsel is one of the strongest enforceability levers you can pull. You can add Illinois attorney services directly in your account.
Attorney services are optional* peace-of-mind add-ons
Why choose HelloPrenup?
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Our prenups are created by licensed attorneys and tailored to Illinois's specific laws, including the Illinois Uniform Premarital Agreement Act.
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No awkward conversations or confusing legal jargon. Our platform walks you through every Illinois-specific decision, together.
Built for complex assets
Illinois earners hold more than salaries. HelloPrenup includes clauses tailored to stock options, RSUs, vesting equity, retirement accounts, and business interests in any LLC, partnership, or sole proprietorship.
A TRUSTED PRENUP THAT'S AFFORDABLE
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We encourage every couple to enter their marriage with full financial transparency and we're starting our relationship with you the same way. Our prenup packages are flexible to adapt to exactly what you and your partner need.
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Frequently asked questions about Illinois prenups
Direct answers to the most common questions about prenuptial agreements in Illinois, with statute and case citations.
The information on this page was last updated in May, 2026. HelloPrenup provides a platform for self-help. The information provided by Hello Prenup along with the content on our website related to legal matters ("Legal Information") is provided for your private use and does not constitute legal advice. We do not review any information you provide us for legal accuracy or sufficiency, draw legal conclusions, provide opinions about your selection of forms, or apply the law to the facts of your situation. If you need legal advice for a specific problem, you should consult with a licensed attorney. Neither Hello Prenup nor any information provided by Hello Prenup is a substitute for legal advice from a qualified attorney licensed to practice in an appropriate jurisdiction.