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 Kentucky, which is not a community property state but rather an equitable distribution state, marital property is divided equitably in the event of a divorce, rather than equally. A marital property partition agreement, known in Kentucky as a postnuptial agreement, is a legal tool that allows married spouses to alter the ownership of marital property, designating certain assets as separate property of one spouse. This type of agreement must be in writing and signed by both parties. It is important for the agreement to be fair and for both spouses to have disclosed all relevant financial information. Kentucky courts will generally uphold a postnuptial agreement if it meets these criteria. However, if the agreement is found to be unconscionable, or if there was fraud, duress, or coercion involved in the making of the agreement, it may be invalidated. Additionally, while spouses can agree to divide property, they cannot use a postnuptial agreement to determine child custody or child support, as these decisions are made based on the best interests of the child. For specific guidance and to ensure the agreement is enforceable, it is advisable to consult with an attorney.