A postnuptial agreement is a written contract signed by spouses after they marry that decides how property, debts and sometimes spousal support will be handled if the marriage ends in divorce or death. It works much like a prenuptial agreement; the main difference is timing, and courts in many states look at postnups more closely because spouses already owe each other duties of fairness.
Key takeaways
- A prenup is signed before marriage, a postnup after; both can divide property and debts.
- Neither can decide child custody or reduce child support below what a court would order.
- Full financial disclosure, voluntary signing and fair terms are essential for enforceability.
What can a postnuptial agreement cover?
- Which assets are separate property and which are marital property.
- How property and debts will be divided in a divorce.
- Ownership of a family business, professional practice or investments.
- Protection of an inheritance or family property.
- Spousal support (alimony), within limits set by state law.
- What each spouse receives at death, alongside wills and estate plans.
What a postnup cannot do
Courts decide child custody and child support based on the child’s best interests at the time of divorce, so agreements that try to fix these in advance are not binding. Most states also refuse provisions that encourage divorce, waive rights in ways that would leave a spouse dependent on public assistance, or set rules for personal matters like household chores.
Prenup vs postnup
| Prenuptial agreement | Postnuptial agreement | |
|---|---|---|
| When signed | Before the wedding | Any time during the marriage |
| Legal framework | Many states follow the Uniform Premarital Agreement Act or a similar law | Often governed by general contract law and spousal duties; rules vary more |
| Court scrutiny | Standard review | Often closer review for fairness and pressure |
| Typical reasons | Protecting pre-marriage assets, business or children from a prior marriage | New business, inheritance, career change, or rebuilding trust after conflict |
What makes a postnuptial agreement enforceable?
- It is in writing and signed by both spouses, often with notarization.
- Both spouses fully disclose their assets, debts and income. Hidden assets are a common reason courts throw agreements out.
- It is signed voluntarily, without threats, deadlines that leave no time to think, or one spouse taking advantage of the other.
- The terms are not unconscionable when signed and, in some states, when enforced.
- Each spouse has the chance to get independent legal advice. It is not required everywhere, but it is the best protection against later challenges.
Some states also require “consideration,” meaning each spouse gets something of value. A small number of states treat postnups with skepticism, so local law matters a great deal.
Why couples sign postnups
- One spouse starts a business or receives a large inheritance.
- One spouse leaves a career to care for children and wants financial security.
- The couple never signed a prenup and wants clarity now.
- The couple is reconciling after a separation or affair and wants defined terms.
Frequently asked questions
How much does a postnuptial agreement cost?
Costs depend on complexity and location. Simple agreements may cost a few thousand dollars in total; agreements involving businesses or significant assets cost more, especially when each spouse has a separate attorney.
Can a postnup be changed or canceled?
Yes, both spouses can amend or revoke it in a new signed written agreement.
Is a postnup useful if we never plan to divorce?
Many couples sign one for clarity during marriage and for estate planning, not because they expect divorce.
Family law is state-specific; speak with a family law attorney in your state before drafting or signing. Related reading: how courts decide child custody.
