A postnuptial agreement—also known as a postnup or a postmarital agreement—is a contract between spouses made after entering into marriage. Laws regarding the enforceability of postnuptial agreements and the property and other rights that may be agreed to vary from state to state.

A postnuptial agreement may be made in anticipation of separation or divorce or may be made to determine the ownership of certain assets when one spouse dies—and may include the surviving spouse’s waiver of certain property rights that would otherwise guarantee the surviving spouse inherit a certain amount of the deceased spouse’s real and personal property (real estate and all other property).

This right that may be waived is sometimes known as the spouse’s elective share and is provided for in state statutes. The elective share provides some minimum amount of inheritance to the surviving spouse and allows the surviving spouse to choose that elective share if it is larger than what the deceased spouse left the surviving spouse by will, for example.

Issues of child custody, alimony or spousal support, life insurance, and other marital assets may also be addressed in a postnuptial agreement.

Child Support May Not Be Adversely Affected by a Postmarital Agreement

The right of a child to support may not be adversely affected by a postmarital agreement.

Reasons A Postmarital Agreement May Be Unenforceable

A postmarital agreement must be in writing and signed by both parties. A postmarital agreement is not enforceable if the party against whom enforcement is requested proves that:

• the party did not sign the agreement voluntarily; or

• the agreement was unconscionable when it was signed and, before signing the agreement, that party: (1) was not provided a fair and reasonable disclosure of the property or financial obligations of the other party; (2) did not voluntarily and expressly waive (in writing) any right to disclosure of the property or financial obligations of the other party beyond the disclosure provided; and (3) did not have and could not reasonably have had adequate knowledge of the property or financial obligations of the other party.

A question of unconscionability of a postmarital agreement is usually decided by the court as a matter of law rather than by the jury as a matter of fact.

Law is Often Located in State Statutes

In many states the law regarding postmarital agreements is located in the state’s statutes—often in the family code or domestic relations code.

In New York, postnuptial agreements are recognized and enforceable contracts between spouses that are made after marriage. These agreements can address various issues such as property division upon death or divorce, spousal waivers of the right to an elective share of the deceased spouse's estate, and other marital rights. However, they cannot adversely affect child support obligations. To be enforceable, a postnuptial agreement must be in writing and signed voluntarily by both parties. It must not be unconscionable at the time of signing, and both parties must have had a fair and reasonable disclosure of each other's financial obligations and property, or have waived the right to such disclosure in writing, and must have had the opportunity to know the other's financial circumstances. If a party did not sign the agreement voluntarily or if the agreement was unconscionable when signed, it may be deemed unenforceable. The determination of unconscionability is typically made by the court. New York's laws on postnuptial agreements are found within the state's domestic relations statutes.