Texas Legal Glossary · Family Law

Partition and Exchange Agreement (Postnuptial)

Written and reviewed by Shane M. Boasberg, founder of SMB Law, PC · Licensed in Texas since 2003 · Updated October 2026

Definition: A partition and exchange agreement is a written contract under Texas Family Code § 4.102 by which married spouses convert community property into the separate property of one spouse, serving as the Texas version of a postnuptial agreement.

Also called: postnuptial agreement, postnup, marital property agreement

What a partition and exchange agreement means in Texas

A partition and exchange agreement is how spouses who are already married rearrange ownership of their property. Under Texas Family Code § 4.102, spouses may at any time partition or exchange between themselves all or part of their community property, existing or to be acquired. Property received in the partition becomes that spouse’s separate property.

The authority comes from the Texas Constitution, article XVI, § 15. Section 4.103 lets spouses agree that income from one spouse’s separate property stays separate, reversing the default Texas rule that such income is community. Under § 4.104 the agreement must be in writing and signed by both spouses.

How it works in practice

Couples sign these agreements for practical reasons. One spouse starts a business and wants to shield the household from its debts. A spouse inherits money and wants the returns kept separate. A couple reconciles after a rough stretch and wants clear lines. The agreement identifies the property and states that it is partitioned to one spouse as separate property. A disclosure of assets usually accompanies the signing.

Enforcement under § 4.105 mirrors the premarital agreement rules. The agreement is enforced unless the challenging spouse proves it was signed involuntarily, or that it was unconscionable when signed and the challenger did not receive fair disclosure, did not waive it in writing, and had no adequate knowledge of the other spouse’s property. Because spouses owe each other fiduciary duties, overreaching by one spouse draws closer scrutiny.

Why it matters in your case

A valid partition agreement controls the property division in a later divorce. The partitioned asset is confirmed as separate property under § 7.001 and is not subject to the just and right division. The flip side is that the agreement binds the spouse who signed it without understanding it. We review existing agreements in every divorce where one exists, because the enforcement defenses in § 4.105 are narrow and fact-driven.

Example

Three years into marriage, Sam opens a restaurant in East Austin. He and his wife, Dolores, sign a partition agreement making the restaurant and its income Sam’s separate property, while the house stays community. When they divorce six years later, the restaurant is confirmed to Sam, and the court divides the house and retirement accounts.

This entry explains Texas law in general terms and is not legal advice for any specific situation. Statutes and case law change; the date above reflects the last review.