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 Hawaii, which is not a community property state but rather an 'equitable distribution' state, marital property is not automatically considered to be owned jointly by both spouses. Instead, during a divorce or legal separation, marital property is divided in a manner that the court deems fair and equitable, which may not necessarily be equal. A marital property partition agreement in Hawaii, also known as a postnuptial agreement, allows married spouses to agree on how their property should be classified as separate or marital and how it should be divided in the event of a divorce. These agreements must be in writing and are subject to certain legal requirements to be enforceable, such as full disclosure of assets and voluntary signing without coercion. If spouses cannot agree on the division of property, they may go to court, and a judge will divide the property based on various factors, including the duration of the marriage, the financial situation of each spouse, and contributions to the marriage. It's important for individuals considering a marital property partition agreement in Hawaii to consult with an attorney to ensure that the agreement is drafted correctly and meets all legal requirements.