Wisconsin Prenuptial Agreement Laws: Rules and Enforceability (2026)

Wisconsin treats a prenuptial agreement as a "marital property agreement" under its Marital Property Act. Wis. Stat. § 766.58(5) lets persons intending to marry each other make one "as if married," and it takes effect only upon their marriage. The agreement must be a document signed by both spouses (§ 766.58(1)), and § 766.58(6) lists the grounds on which it is not enforceable.

Information last verified on 2026-10-10. This article has not been reviewed by a licensed lawyer.

Jurisdiction scope: This article covers premarital and marital property agreements under Wisconsin Statutes § 766.58, with the divorce property-division rule in § 767.61(3)(L) and the related provisions of chapters 766 and 767 it cites. The history note on § 766.58 lists 2025 Wisconsin Act 234, which changed only the register-of-deeds cross-reference in § 766.58(11); quotations are from the text published on the Wisconsin Legislature's website when this page was verified. It does not cover custody terms, tax or estate planning, or other states' law. It is general information, not a template or drafting guide.

Which law governs prenups in Wisconsin?

Wisconsin's rules are in chapter 766, the Marital Property Act. Chapter 766 is Wisconsin's Marital Property Act, and § 766.96 directs that it be construed to make the law uniform among states enacting it. It uses one term, "marital property agreement," for agreements made before or during marriage.

Section 766.58(5) provides:

"(5) Persons intending to marry each other may enter into a marital property agreement as if married, but the marital property agreement becomes effective only upon their marriage."

Wisconsin's statute of frauds requires agreements made upon consideration of marriage to be in writing and signed by the party charged, but it expressly does not apply to a marital property agreement that complies with chapter 766 (§ 241.02(1)(c), (2)).

Formal requirements

Section 766.58(1) sets the basic form:

"A marital property agreement shall be a document signed by both spouses. Only the spouses may be parties to a marital property agreement. A marital property agreement is enforceable without consideration."

Section 766.58 does not require the agreement to be notarized or witnessed. Recording is optional: under § 766.58(11), "Married persons or persons intending to marry each other may record a marital property agreement in the county register of deeds office under s. 59.43 (1c) (a)."

Section 766.58 also does not set a waiting period between receiving a proposed agreement and signing it.

When a Wisconsin prenup is not enforceable

Section 766.58(6) places the burden on the spouse resisting the agreement. It opens: "A marital property agreement executed before or during marriage is not enforceable if the spouse against whom enforcement is sought proves any of the following:"

Because the two parts are joined by "and," lack of disclosure alone does not meet this ground if the spouse had notice of the other's property or financial obligations.

Lawyers and independent counsel

Section 766.58 does not require either party to have a lawyer. Subsection (8) addresses representation directly:

"... the fact that both parties are represented by one counsel or that one party is represented by counsel and the other party is not represented by counsel does not by itself make a marital property agreement unconscionable or otherwise affect its enforceability."

A lawyer licensed in Wisconsin can draft or review an agreement, but the statute does not make that a condition of enforceability.

Spousal support and child support limits

An agreement may address the modification or elimination of spousal support (§ 766.58(3)(d)), within limits. Section 766.58(9) provides: "Modification or elimination of spousal support during the marriage may not result in a spouse having less than necessary and adequate support, taking into consideration all sources of support." The same subsection also lets the court require support to avoid a spouse's eligibility for public assistance at dissolution of the marriage or at death.

At divorce, the maintenance statute lists "any mutual agreement made by the parties before or during the marriage concerning any arrangement for the financial support of the parties" as one of the factors the court considers before deciding whether to order maintenance (§ 767.56(1c)(h)). Unlike § 767.61(3)(L) for property, it does not state that such an agreement binds the court.

Child support cannot be bargained away. Section 766.58(2) states: "A marital property agreement may not adversely affect the right of a child to support." This page does not cover agreement terms about custody. For support amounts generally, see Wisconsin alimony laws.

How a divorce court treats a prenup

At divorce, a second statute applies to written property agreements. Section 767.61(3)(L) lists, as a property-division factor:

"Any written agreement made by the parties before or during the marriage concerning any arrangement for property distribution; such agreements shall be binding upon the court except that no such agreement shall be binding where the terms of the agreement are inequitable as to either party. The court shall presume any such agreement to be equitable as to both parties."

In Button v. Button, 131 Wis. 2d 84, 388 N.W.2d 546 (1986), the court applied the divorce statute's "inequitable" standard for written property agreements. Under the three-part test it set out, an agreement is not binding if a spouse did not make fair and reasonable disclosure, did not enter the agreement voluntarily and freely, or if the substantive terms are not fair to each spouse, and it remanded because the circuit court had not applied that test. Button held that disclosure and voluntariness are judged when the agreement was signed, and that substantive fairness is judged when it was signed and, if circumstances significantly changed afterward, also at divorce. It also said a spouse's independent knowledge of the other's finances can substitute for disclosure.

Button involved a 1974 postnuptial agreement and construed the divorce statute then numbered § 767.255(11), now § 767.61(3)(L); the Legislature's annotations to § 767.61 and § 766.58 still cite it on whether a property agreement is inequitable.

Changing or revoking a prenup

Section 766.58(4) provides: "A marital property agreement may be amended or revoked only by a later marital property agreement." A change therefore has to meet the same signed-document rule in § 766.58(1).

A divorce, annulment or legal separation also affects death-related terms. "Unless the judgment provides otherwise," such a judgment revokes a provision in a marital property agreement under § 766.58 that provides for dispositions at death (§ 767.375(1)).

Time limits for enforcing a prenup

Section 766.58(13)(a) pauses the clock during the marriage: "any statute of limitations applicable to enforcement of the provision is tolled until dissolution of the marriage or termination of the marriage by death, respectively." After a spouse's death, § 766.58(13)(b) bars claims 6 months after the estate inventory is filed, or 8 months after death if no estate is opened. If an amended inventory is filed, an action about information new to that inventory may be brought within 6 months after it is filed, and the court may extend the 6-month period for cause if a motion is made within it (§ 766.58(13)(b)1., (c)).

Postnuptial agreements in Wisconsin

Wisconsin uses the same statute for agreements made after the wedding. Section 766.58(6) applies to an agreement "executed before or during marriage," and § 767.61(3)(L) covers written agreements made "before or during the marriage."

Agreements made in connection with a divorce are a different matter. The Legislature's annotations to § 767.34 describe such stipulations as recommendations to the court.

Wisconsin's marital property system

Wisconsin is a marital property state. Section 766.001(2) states: "It is the intent of the legislature that marital property is a form of community property." At divorce, § 767.61(3) presumes an equal division of property that is not excepted from division. For how that division works, see Wisconsin divorce laws.

Disclaimer: This article provides general legal information about marital property agreements under Wisconsin Statutes chapters 766 and 767 as verified on 2026-10-10. It is not legal advice and is not a template. For advice about your situation, consult a lawyer licensed in Wisconsin or contact the Wisconsin State Law Library.

Related

• Prenuptial agreement laws in every state
• Wisconsin divorce laws
• Wisconsin alimony laws

Last updated: 2026-10-10.

Frequently Asked Questions

Are prenups enforceable in Wisconsin?

Yes. Wis. Stat. § 766.58(5) lets persons intending to marry enter into a marital property agreement that takes effect on marriage, and it is enforceable unless the resisting spouse proves one of the grounds in § 766.58(6).

Does a prenup have to be notarized in Wisconsin?

Section 766.58 does not require notarization or witnesses. It requires a document signed by both spouses (§ 766.58(1)), and recording with the county register of deeds is optional (§ 766.58(11)).

Do both parties need their own lawyer for a Wisconsin prenup?

No. Under § 766.58(8), one lawyer representing both parties, or only one party having a lawyer, does not by itself make the agreement unconscionable or otherwise affect its enforceability.

Can a Wisconsin prenup waive alimony?

A marital property agreement may address spousal support (§ 766.58(3)(d)), but at divorce the court treats an agreement about support as one factor in deciding maintenance (§ 767.56(1c)(h)), not as binding. Section 766.58(9) also limits support changes during the marriage and lets the court require support to keep a spouse off public assistance.

Can a prenup decide child support in Wisconsin?

No. Section 766.58(2) states that a marital property agreement may not adversely affect the right of a child to support.

Can a divorce court ignore a prenup in Wisconsin?

Under § 767.61(3)(L), a written property agreement binds the divorce court and is presumed equitable, except that it is not binding where its terms are inequitable as to either party.