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 Nebraska, the concept of community property as recognized in some states does not apply, as Nebraska is an 'equitable distribution' state rather than a 'community property' state. This means that in the event of a divorce, marital property is not automatically split 50/50 but is divided in a manner that the court deems fair and equitable, which may not necessarily be equal. A marital property partition agreement, known in Nebraska as a postnuptial agreement, is a legal document where married spouses agree on how to divide their property 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 liabilities, and both parties must enter into the agreement voluntarily and without coercion. The agreement cannot be unconscionable or unfair at the time of its execution. If spouses wish to partition jointly owned property without a divorce, they may need to file a civil lawsuit for partition, where the court will divide the property equitably. It is advisable for spouses considering a postnuptial agreement or property partition to consult with an attorney to ensure the agreement complies with Nebraska law and adequately protects their interests.