Wisconsin Prenuptial Agreement
Wisconsin prenuptial agreements are governed by Wisconsin Statute § 766.58 and the Button test. Courts apply dual review — unconscionability is assessed at both signing and divorce — under a disjunctive three-part standard where any one prong is sufficient to invalidate. Courts may override a support waiver only to the extent necessary to avoid public assistance eligibility, and cannot require more. One practical risk: Wisconsin courts have voided agreements where spouses commingled assets or operated businesses jointly during the marriage, treating the prenup as abandoned.
Bottom line: Wisconsin earns a C+ grade. Dual review and a disjunctive challenge standard create enforcement risk, but a capped alimony floor and a pro-enforcement track record for well-executed agreements give Wisconsin more certainty than most dual-review states. Keep assets strictly separate during the marriage. A prenup is still far better than none.
Wisconsin Prenup Enforceability Rating: C+
Wisconsin Prenup Laws: Key Statutes Explained
Wisconsin Statute § 766.58
Separate Property
All assets can remain separate property, avoiding costly divorce settlements. Joint assets and debts titled in both names are split 50/50 as marital property.
Unconscionability at Execution AND Enforcement
Wisconsin applies a "two looks" standard—courts review unconscionability both at execution AND at enforcement. A prenup may be invalidated if it was unfair when signed OR if unforeseeable changed circumstances make it unfair at divorce.
Unconscionability Standard
A prenup is unenforceable if the challenging spouse proves ANY of: (1) unconscionable when made, OR (2) involuntary execution, OR (3) lack of fair financial disclosure without actual notice of the other's finances.
Public Assistance Spousal Support Floor
Spousal support can be waived entirely, but courts may override waivers if enforcement would make one spouse eligible for public assistance. Courts can require only enough support to avoid public assistance eligibility, notwithstanding the prenup.
Timing
No minimum specified, but we recommend signing the prenup at least 30-60 days before the wedding, with both parties having 2-3 weeks to review the final version to minimize challenge risk.
Independent Counsel
Not required, but separate counsel dramatically strengthens enforceability if the agreement is later challenged.
Financial Disclosure
"Fair and reasonable disclosure" of property and financial obligations required, statute does not address if written waiver is acceptable (PerfectPrenup includes both out of precaution).
Medium Burden to Challenge
Challenging party must prove the prenup is invalid by preponderance of evidence (standard civil burden, not clear and convincing).
Child Support and Custody
Child support and custody clauses are unenforceable and could undermine the entire agreement. Do not include.
Wisconsin Prenuptial Agreement Court Cases
Wisconsin's biggest weakness is where married couples operate a business together. To avoid equal division when one party provides minimal contributions, a contract should be drawn outlining responsibilities and ownership percentage.
Brandt v. Brandt, 145 Wis. 2d 394, 427 N.W.2d 126 (Ct. App. 1988)
The court declined to enforce a postnuptial agreement where the parties completely ignored it throughout the marriage and commingled their assets so thoroughly that meaningful enforcement was impossible.
Krejci v. Krejci, 2003 WI App 160, 266 Wis. 2d 284, 667 N.W.2d 780 (2003)
The court refused to enforce a prenuptial agreement excluding an inherited resort from the marital estate because the parties operated it as a partnership for 18 years, never discussed the agreement during the marriage, commingled their finances, and both spouses' efforts contributed to the resort's appreciation in value.
Steinmann v. Steinmann, 309 Wis. 2d 29, 749 N.W.2d 145, 2008 WI 43 (2008)
The court held that when separate property is used to purchase property that is then titled jointly, this demonstrates donative intent and transmutes the property from individual to marital property, resulting in Rose being ordered to pay Tony $764,000 for his share of their $2.2 million Lake Geneva home despite it being purchased partially with her individual settlement funds.
Button v. Button, 131 Wis. 2d 84, 388 N.W.2d 546 (1986)
The Wisconsin Supreme Court reversed the circuit court's enforcement of a 1974 postnuptial agreement and established the foundational "Button test" requiring prenuptial agreements to satisfy three requirements: fair and reasonable financial disclosure, voluntary and free entry, and substantive fairness both at execution and at enforcement.
Gardner v. Gardner, 190 Wis. 2d 216, 527 N.W.2d 701 (Ct. App. 1994)
The court upheld a prenuptial agreement giving the husband (who had over $3 million in assets) substantially all marital property, finding that five days' notice before the wedding was adequate when the wife had independent counsel, and that disparity in property division alone does not make an agreement unfair.
Greenwald v. Greenwald, 154 Wis. 2d 767, 454 N.W.2d 34 (Ct. App. 1990)
The court enforced a premarital agreement between a retired 70-year-old widower and his former housekeeper, holding that if a party's conduct demonstrates that specific knowledge of the other party's property and finances is not important to them, the agreement may not be defective even without formal financial disclosure.
5-Step Checklist: How to Sign & Execute a Prenup in Wisconsin
Step 1: Download and read the Wisconsin prenuptial agreement
Start with our free template. It is written for Wisconsin-specific statutes and case law under Wis. Stat. § 766.58 and the Button v. Button three-part enforceability test. Read it in full — know what you are getting into legally with marriage. The 15+ pages is written thoroughly to include rebuttals to common legal challenges and fallback provisions.
Step 2: Draft changes on your own
See a clause you don't like? Copy it into an AI like Claude, explain what you'd like to change or what you want the clause "to do." Save any changes as a separate alternate version — don't overwrite the original. Bring both versions to your attorney review. Note: AI is often gender-biased and crafts terms beyond what is legally required. Push back on its output.
Step 3: Find a lawyer in your state
Find a matrimonial or divorce attorney in your state. Avvo, Findlaw, and Justia are good. Look for someone with 10+ years experience. Call or email and ask them how much to review your draft prenup and help with signing. Send them your draft.
Step 4: Meet your lawyer 4–6 months before the wedding
Our recommendation: sign the prenup before proposing. That way, you both get the legal work out of the way, and you know this is the right person to marry. Already proposed? 4–6 months before the wedding should leave you enough time to give your spouse 2 weeks to review the final draft and have it signed 60+ days before the wedding. Wisconsin has no statutory minimum timing, but courts weigh adequate review time as a Button voluntariness factor. Gardner upheld a five-days-before signing when the wife had independent counsel; Matson-style last-minute ambushes without attorney access create real challenge risk.
Step 5: Sign with your attorneys and store the agreement
Execute the agreement with both attorneys present — independent counsel is "the best evidence" of voluntary, knowing execution under the Button test. No attorneys? Use a standalone notary at minimum. Each party keeps a signed original, and so should each party's attorney. Store yours somewhere secure like a safety deposit box. Create a .pdf and save it via a backup drive and email.
Wisconsin Prenuptial Agreement: Frequently Asked Questions (2026)
What is a prenuptial agreement?
A legal contract signed before marriage that determines how assets, debts, and finances are handled if the marriage ends. We recommend assets and debts are kept separate, unless held jointly, where they are split 50/50. Alimony is modified to incentivize larger families and longer marriages, rather than divorce. A privacy clause allows the growth of an intimate, trusting relationship. A dispute resolution clause moves proceedings out of an expensive courtroom and into mediation or arbitration, lowering conflict to maintain a workable relationship.
How much does a prenup cost in Wisconsin?
Attorney-drafted from scratch: $1,500–$5,000+ per side. The smarter approach: start with our free Wisconsin template, draft any changes with an AI like Claude, then hire an attorney only to review and assist with signing. The bill should be around $500 per side.
Are prenups enforceable in Wisconsin?
Yes, but Wisconsin earns a C+ rating. Courts apply the Button three-part test with dual review — the agreement must be fair both at signing and at divorce. Wisconsin's marital property (community property) system and its commingling/transmutation case law (Brandt, Krejci, Steinmann) add meaningful enforcement risks. Courts may also decline to enforce an agreement the parties didn't actually observe during marriage. A prenup is still far better than none.
What makes a prenup invalid in Wisconsin?
Under Button, any one of three grounds is sufficient: (1) no fair and reasonable disclosure of property and financial obligations; (2) not entered into voluntarily and freely; or (3) substantively unfair — either at execution OR at enforcement due to changed circumstances. Common failures: commingling assets in ways inconsistent with the prenup (Brandt); operating a "separate" business as a joint partnership without maintaining separation (Krejci); titling property jointly when it was supposed to stay separate (Steinmann). Leave child custody and support out entirely.
Do I need a lawyer to get a prenup in Wisconsin?
Not legally required — § 766.58(8) expressly states that one party being unrepresented does not by itself make the agreement unconscionable. But independent counsel is the clearest evidence of knowing, voluntary execution under Button, and courts weigh it heavily when the agreement is challenged. Gardner upheld a one-sided agreement signed five days before the wedding specifically because the wife had independent counsel. Use the template to cut drafting costs — don't skip the attorney.
What should a Wisconsin prenuptial agreement include?
Our Wisconsin template is built around six core principles:
- Separate property — assets and debts stay with the party who acquired them, minimizing conflict
- Joint assets and debts — anything both parties sign for together is split 50/50
- Marital home — ownership is tracked as a percentage of contribution, so each party gets back what they put in
- Spousal support — structured to incentivize larger families and longer marriages, not divorce
- Full financial disclosure — all assets, debts, and income over $1,000, listed in the exhibits, satisfying the Button fair disclosure requirement; our template also includes a written disclosure waiver as a backup, given Greenwald's holding that actual knowledge can substitute for formal disclosure
- Privacy clause — keeps financial and personal details private, supporting a trusting relationship
Leave out child custody and support entirely — Wisconsin courts will not enforce them and they can invalidate the rest of the agreement.
Does Wisconsin's property law make a prenup important?
Yes — more so than in most states. Wisconsin operates under the Uniform Marital Property Act, one of only two non-Louisiana states to do so. Like a community property system, all income earned and property acquired during the marriage is presumptively marital property subject to equal division at divorce. A prenup overrides this default. One Wisconsin-specific vulnerability: separate property can be transmuted into marital property by titling it jointly (Steinmann), commingling it with marital funds, or treating it as a shared asset over the course of the marriage. The prenup should address how separate property stays separate — and both parties should actually live by it.
How far in advance should I get a prenup in Wisconsin?
Sign 60+ days before the wedding. Give your spouse at least two weeks to review with their own attorney. Wisconsin has no statutory minimum, but courts weigh review time as a voluntariness factor under Button. Gardner upheld five days before the wedding when the wife had independent counsel; agreements sprung without notice or attorney access are much more vulnerable. Contact an attorney 4–6 months before the wedding. Best practice: sign before proposing — no time pressure, and you'll be confident in whom you are choosing to marry.
What is the biggest Wisconsin-specific risk for prenup enforcement?
Commingling and non-observance. Wisconsin courts take seriously the requirement that parties actually live by their prenup. Brandt voided a postnuptial agreement because the parties completely ignored it and commingled assets throughout marriage. Krejci voided a prenup excluding an inherited resort because both spouses operated it as a joint partnership for 18 years. Steinmann held that jointly titling property purchased with separate funds demonstrates donative intent and transmutes it to marital property. The practical lesson: if your prenup says an asset is separate, keep it titled separately, keep the accounts separate, and document that you're treating it as separate year after year. Don't let conduct during the marriage contradict what the agreement says — Wisconsin courts will look at both.