What is Postnuptial Agreement?
Updated January 24, 2026
A written contract between spouses, signed after the wedding while they intend to stay married, that sets out how property, debts and sometimes support will be handled if the marriage ends.
Understanding Postnuptial Agreement
A postnuptial agreement (also called a marital or postmarital agreement) covers much of the same ground as a prenuptial agreement but is signed during the marriage. Couples sign them after a change such as an inheritance, starting a business, or a reconciliation. Because spouses already owe each other duties of good faith, some states look more closely at postnuptial agreements than at prenups. States that have adopted the Uniform Premarital and Marital Agreements Act apply the same core requirements to both, such as voluntary consent, access to independent legal representation and adequate financial disclosure. Other states decide enforceability under their own statutes or case law, so the rules vary widely. Like a prenup, a postnuptial agreement generally cannot decide custody or limit child support.
Examples
- 1An agreement signed after one spouse inherits a family property, keeping it separate
- 2A postnuptial agreement made as part of a reconciliation after a separation
- 3An agreement that a new business started during the marriage will belong to one spouse
Why This Matters in Legal Cases
Postnuptial agreements are often signed during a stressful period in the marriage, which makes questions about pressure, disclosure and fairness more likely when one spouse later tries to enforce it. Because states differ on how they treat these agreements, the same document may be enforceable in one state and not in another.
Frequently Asked Questions
Are postnuptial agreements enforceable?
What is the difference between a postnuptial agreement and a settlement agreement?
Can a postnuptial agreement waive alimony?
Related Terms
Prenuptial Agreement
A written contract signed by two people before they marry that sets out how property, debts and sometimes spousal support will be handled if the marriage ends by divorce or death.
Separate Property
Property that belongs to one spouse alone, typically property owned before the marriage or received during the marriage as a gift or inheritance, which is usually not divided in a divorce.
Marital Settlement Agreement
A written contract between divorcing or separating spouses that resolves the issues in their case, such as property division, debts, spousal support, child support and custody, and that is usually incorporated into the court's final judgment.
Marital Property
Assets and debts acquired during the marriage that are subject to division in a divorce, as opposed to separate property owned before marriage or received as gifts/inheritance.
Divorce
The legal dissolution of a marriage by a court or other competent body, ending the marital relationship and dividing assets, debts, and responsibilities.
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