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 Florida, which is an equitable distribution state rather than a community property state, marital property is not automatically considered joint property. Instead, marital assets and liabilities are distributed in an equitable fashion in the event of a divorce. A marital property partition agreement, known in Florida as a postnuptial agreement, allows spouses to agree on how to divide their property and debts should the marriage end. This agreement can include the division of both current and future assets and liabilities. It must be in writing, signed by both parties, and executed with the same formalities as a deed to be enforceable. Florida Statutes specifically address the requirements and enforceability of these agreements under Chapter 61, which governs marital and family law. If spouses cannot agree on the division of property, a Florida court will divide the property equitably, which does not necessarily mean equally, based on a set of factors outlined in the statutes. It's important to note that such agreements must be entered into voluntarily and with full disclosure by both parties to be considered valid by the court.