Kansas Prenuptial Agreement Laws: Requirements and Enforceability

Prenuptial agreements are enforceable in Kansas under the Uniform Premarital Agreement Act, enacted as K.S.A. 23-2401 to 23-2411. Under K.S.A. 23-2403, a premarital agreement must be in writing and signed by both parties, and K.S.A. 23-2407 sets out when a court will refuse to enforce one.

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

Jurisdiction scope: This article covers premarital agreements under the Kansas Uniform Premarital Agreement Act, K.S.A. 23-2401 to 23-2411, and postnuptial agreements as addressed in In re Marriage of Traster, 301 Kan. 88 (2014). It does not cover agreements signed before the act took effect, how Kansas courts have applied K.S.A. 23-2407 in specific cases, tax or estate-planning effects, or other states' law. It is general information, not a template or drafting guide.

Are prenups enforceable in Kansas?

Yes, if they meet the act's requirements and the party challenging the agreement cannot prove one of the defenses in K.S.A. 23-2407. The act defines a premarital agreement as an agreement between prospective spouses made in contemplation of marriage and to be effective upon marriage (K.S.A. 23-2402(a)).

The act names itself in K.S.A. 23-2401: "This act may be cited as the 'uniform premarital agreement act.'" It was enacted by L. 1988, ch. 204, effective July 1, 1988.

Requirements for a valid prenup in Kansas

K.S.A. 23-2403 provides: "A premarital agreement shall be in writing and signed by both parties. It is enforceable without consideration."

• Writing and signatures. Both parties must sign a written agreement.
• No consideration needed. The agreement is enforceable without consideration.
• No notary or witness rule in the act. K.S.A. 23-2403 does not require notarization or witnesses.
• Effective date. Under K.S.A. 23-2405, "A premarital agreement becomes effective upon marriage."

The act, K.S.A. 23-2401 to 23-2411, does not require each party to have a separate lawyer and does not set a waiting period between receiving the agreement and signing it. Whether a party had a lawyer or time to review can still bear on whether they signed voluntarily, which is a defense under K.S.A. 23-2407(a)(1). A lawyer licensed in Kansas can review an agreement for either party.

What can make a prenup unenforceable in Kansas

K.S.A. 23-2407(a) gives two separate defenses. The party resisting enforcement carries the burden of proof on each.

1. Involuntariness. The agreement is not enforceable if the party proves they did not execute it voluntarily (K.S.A. 23-2407(a)(1)).

2. Unconscionability plus lack of disclosure. Under K.S.A. 23-2407(a)(2), the party must prove the agreement "was unconscionable when such agreement was executed and, before execution of the agreement, all of the following applied to that party":

• they were not provided a fair and reasonable disclosure;
• they did not voluntarily and expressly waive, in writing, any right to disclosure; and
• they did not have, or reasonably could not have had, an adequate knowledge of the other party's property or financial obligations.

All of those conditions must apply, together with unconscionability at signing. Unconscionability is judged as of the date the agreement was executed, not the date of the divorce. Under K.S.A. 23-2407(c), the court decides the issue of unconscionability as a matter of law.

Spousal support waivers

K.S.A. 23-2407(b) addresses agreement terms that modify or eliminate spousal support. If such a provision modifying or eliminating spousal support would make one party eligible for public assistance at the time of separation or dissolution of marriage, the court may, notwithstanding the agreement, require the other party to provide support to the extent necessary to avoid that eligibility. For how Kansas courts set maintenance, see Kansas alimony laws.

What a Kansas prenup cannot do

K.S.A. 23-2404(b) provides: "The right of a child to support may not be adversely affected by a premarital agreement." Under K.S.A. 23-2404(a)(8), the parties may contract on other matters that do not violate public policy or a statute imposing a criminal penalty.

K.S.A. 23-2404 does not address child custody or parenting time. This page does not cover whether a Kansas court would follow a custody term in a premarital agreement.

Changing or revoking a prenup

K.S.A. 23-2406 provides: "After marriage, a premarital agreement may be amended or revoked only by a written agreement, signed by the parties." The amendment or revocation is enforceable without consideration.

Time limits and void marriages

Under K.S.A. 23-2409, "Any statute of limitations applicable to an action asserting a claim for relief under a premarital agreement is tolled during the marriage of the parties to the agreement. However, equitable defenses limiting the time for enforcement, including laches and estoppel, are available to either party."

If the marriage itself turns out to be void, K.S.A. 23-2408 provides that "an agreement that would otherwise have been a premarital agreement is enforceable only to the extent necessary to avoid an inequitable result."

Postnuptial agreements in Kansas

The Uniform Premarital Agreement Act covers agreements made before marriage. For an agreement made during marriage, the Kansas Supreme Court in In re Marriage of Traster, 301 Kan. 88, 339 P.3d 778 (2014), held: "We hold the couple's agreement is controlled by K.S.A. 60-1610(b)(3), which requires a separation agreement to be incorporated into the divorce decree if the court finds it is 'valid, just and equitable.'"

The court also abrogated the older public-policy analysis under which a postnuptial agreement was suspect for encouraging divorce, and it remanded the case for a just-and-equitable review. The current Kansas statute on separation agreements, K.S.A. 23-2712, likewise provides for incorporating into the decree a separation agreement the court finds valid, just and equitable.

Traster applies this rule to agreements made during marriage that provide for a spouse's property rights in the event of divorce or separation, regardless of whether the spouses intend to remain married when they sign. The Revisor's annotation to K.S.A. 23-2401 notes that spouses may contract to make the premarital agreement act apply to a postnuptial agreement (Davis v. Miller, 269 Kan. 732 (2000)), and Traster describes Davis as upholding the spouses' right to bind themselves to the premarital act's unconscionability standard.

Kansas property division without a prenup

Kansas divides property by equitable division, not community property. Under K.S.A. 23-2802, the decree shall divide the real and personal property of the parties, whether owned before the marriage or acquired during it, using the factors in 23-2802(c). See Kansas divorce laws.

Disclaimer: This article provides general legal information about premarital and postnuptial agreements under the Kansas Statutes Annotated and Kansas Supreme Court case law, verified on 2026-10-10. It is not legal advice and is not a template. For advice about a specific agreement, consult a lawyer licensed in Kansas.

Related

• Prenuptial agreement laws in every state
• Kansas divorce laws
• Kansas alimony laws
• Kansas child support laws

Last updated: 2026-10-10.

Frequently Asked Questions

Are prenups legal in Kansas?

Yes. Kansas enforces premarital agreements under the Uniform Premarital Agreement Act, K.S.A. 23-2401 to 23-2411, if the agreement is in writing, signed by both parties (23-2403), and not defeated by a defense in 23-2407.

Does a prenup have to be notarized in Kansas?

K.S.A. 23-2403 requires a premarital agreement to be in writing and signed by both parties, and that section does not require notarization or witnesses.

Do both parties need a lawyer for a Kansas prenup?

The Kansas act (K.S.A. 23-2401 to 23-2411) does not require independent counsel. Whether a party signed voluntarily is a defense under 23-2407(a)(1), and a Kansas lawyer can review an agreement for either party.

How can a prenup be challenged in Kansas?

Under K.S.A. 23-2407(a), the challenging party must prove involuntary signing, or that the agreement was unconscionable when signed and that, before signing, they lacked fair disclosure, did not waive disclosure in writing, and had no adequate knowledge of the other's finances.

Can a Kansas prenup waive alimony?

A prenup can address spousal support, but under K.S.A. 23-2407(b) a court may require support to the extent needed to keep a spouse from becoming eligible for public assistance at separation or divorce.

Can a prenup decide child support in Kansas?

No. K.S.A. 23-2404(b) provides that the right of a child to support may not be adversely affected by a premarital agreement.

Are postnuptial agreements enforceable in Kansas?

In In re Marriage of Traster (2014), the Kansas Supreme Court held that an agreement made during marriage that provides for a spouse's property rights on divorce or separation is treated as a separation agreement that must be incorporated into the divorce decree if the court finds it valid, just and equitable.