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 North Carolina, marital property is not classified as community property, as North Carolina 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 is equitable, which may not always be equal. A marital property partition agreement, known in North Carolina as a postnuptial agreement, is a legal document where spouses can agree to change the ownership of marital property to separate property after marriage. These agreements must be in writing and notarized to be enforceable. The agreement allows spouses to decide how their property should be divided in the event of a divorce or death, rather than leaving the decision solely to the courts. If spouses cannot agree on the division of property, the courts will intervene and divide the property through a lawsuit, typically during the divorce proceedings. The specifics of these agreements and the division of property through court action are governed by North Carolina General Statutes, primarily within Chapter 50 - Divorce and Alimony, and Chapter 52 - Equitable Distribution of Property.