A marital property partition agreement—also known as a partition and exchange agreement, a postmarital agreement, or a postnuptial agreement—is an agreement between spouses during marriage to convert marital property (also known as community property in some states) to one spouse’s separate property.

Property that is jointly owned by spouses or domestic partners (often owned as joint tenants with a right of survivorship) may also be partitioned or divided in a lawsuit or court action rather than by agreement of the spouses.

Laws regarding marital property partition agreements vary from state to state and are generally located in a state’s statutes—often in the family code or domestic relations code.

In West Virginia, marital property is not classified as community property, as West Virginia is an equitable distribution state rather than a community property state. This means that during a divorce, marital property is divided in a manner that the court deems fair, which may not necessarily be equal. A marital property partition agreement in West Virginia, commonly referred to as a postnuptial agreement, allows married spouses to agree on how their marital property should be divided in the event of a divorce or death. Such agreements must be in writing and are subject to certain legal requirements to be enforceable, including full disclosure of assets and voluntary execution without duress or undue influence. If spouses wish to partition or divide jointly owned property without a court action, they can do so through a written agreement, provided it meets the legal standards for contracts in the state. However, if they cannot agree, they may seek a court action to partition the property. The specifics of these agreements and actions are governed by West Virginia's statutes, particularly within the realms of family law and contract law.