How Do Postnuptial Agreements Work?

You've probably heard of prenuptial agreements ("prenups")—contracts couples sign before they get married, usually to decide how they'll deal with their finances if and when they get divorced. Some couples sign similar contracts after they've married: postnuptial agreements. Still, there are a few important differences between prenuptial and postnuptial agreements. "Postnups" are also different than agreements spouses sign when they're separating or divorcing.

What Is a Postnuptial Agreement?

A postnuptial agreement—also called a post-marriage or marital agreement—is a contract that spouses sign after they've gotten married but before they're separating or divorcing. Like prenups, most postnups focus on how the spouses will divide their property and debts if and when their marriage ends. They may also address other financial issues, such as their inheritance rights when one spouse dies.

Of course, couples might want to agree about other issues in their marriage, but courts will only enforce certain provisions in prenuptial agreements. (More below on what postnups can and can't accomplish.)

Prenups vs. Postnups

Postnups are like prenups in some ways and different in other ways. Couples generally have similar goals for both types of agreements: to clarify their financial rights and responsibilities in the event of a divorce—and sometimes during the marriage or after one spouse dies.

Like with prenups, judges will only enforce postnups if they meet certain requirements. Those requirements vary from state to state, but there are some common principles.

Basic Rules for Postnuptial Agreements

Some of the same basic requirements for enforceable contracts apply to postnuptial agreements. In general, they should:

• be in writing
• be signed voluntarily by both spouses without coercion
• not involve fraud or misrepresentation, and
• not be unconscionable—that is, so unfair or one-sided that they shock the conscience.

Fairness and Transparency

Most judges hold postnuptial agreements to a higher standard of fairness and transparency than agreements between couples who aren't yet married. In large part, that's because state laws generally recognize that spouses have a fiduciary relationship—a relationship of trust and an expectation that they'll act in each other's interest.

In some states, this fiduciary duty is particularly strong. Under California law, for instance, spouses have a duty of "highest good faith and fair dealing." Neither can take unfair advantage of the other, and they must give each other complete and truthful information about all of their assets and debts. (Cal. Fam. Code § 721 (2024).)

Similarly, Ohio law provides that a postnuptial agreement won't be enforceable unless both spouses knew and understood the value, nature, and extent of all of their property when they signed the agreement. (Ohio Rev. Code § 3103.061(C) (2024).)

Aside from specific legal requirements for postnuptial agreements, many judges recognize that some spouses may be in a more vulnerable position during the marriage than before the wedding—and therefore might be more susceptible to being pressured into giving up some important financial rights in a postnup. As a result, judges tend to scrutinize these marital agreements closely when they're deciding whether to enforce the agreement during a divorce or other legal proceeding.

Consideration: What Does Each Spouse Get Out of a Postnuptial Agreement?

"Consideration" is the legal term for what one party to a contract gets in return for fulfilling a promise. With prenuptial agreements, the mutual promise to get married is generally considered adequate consideration. That may or may not be true for postnuptial agreements.

• In some states, such as New York, postnuptial agreements aren't considered valid if they don't include valuable consideration, and promising to stay in the marriage isn't enough. For instance, one court wouldn't enforce an agreement providing that the wife gave up her claims to her husband's business property because he hadn't given her anything in return. (Whitmore v. Whitmore, 8 A.D.3d 371 (N.Y. App. Div. 2004).)
• Courts in other states have held that a spouse's agreement to drop divorce plans—even if only for a while—counted as adequate consideration in exchange for agreements about the couple's property. (Hall v. Hall, 27 N.E.3d 281 (Ind. Ct. App. 2015); In re Marriage of Tabassum and Younis, 881 N.E.2d 396 (Ill. Ct. App. 2007).)
• Mutual waivers might be considered adequate consideration in a postnup, such as when both spouses agree to give up their rights to inherit from each other.

However, not all states require consideration in postnups. For example, Colorado law specifically says that both premarital and marital agreements are enforceable even if they don't provide any consideration. And under Florida law, a spouse may waive inheritance rights as a surviving spouse in a prenup or postnup without receiving any consideration in return for that waiver. (Colo. Rev. Stat. § 14-2-306; Fla. Stat. § 732.702 (2024).)

Other Legal Requirements for Postnuptial Agreements

Some states impose additional requirements for postnuptial agreements. For example:

• Legal representation. Under Minnesota law, postnuptial agreements are enforceable only if both spouses had their own separate lawyers when signing, while the standard for prenups is simply that each of them had a "meaningful opportunity" to consult with a lawyer of their choosing. In contrast, California's requirement for independent legal counsel when signing a prenuptial agreement does not apply to postnuptial agreements. (Minn. Stat. § 519.11; Cal. Fam. Code § 1615(c)(1) (2024); In re Marriage of Friedman, 122 Cal.Rptr.2d 412 (Cal. Ct. App. 2002).) (More below on whether you need a lawyer before signing a postnup.)
• Timing before divorce. Depending on the law in your state, a judge might not recognize a postnup signed too close to the end of the marriage. For example, Minnesota law presumes that a postnuptial agreement isn't enforceable if either party files for divorce or legal separation within two years after signing the agreement. (Minn. Stat. § 519.11, subd. 1a, (1)(d) (2024).)
• No promotion of divorce. In Ohio, a postnup won't be enforceable if it encourages divorce. (Ohio Rev. Code § 3103.061(D) (2024).)
• Waiver of probate rights. State laws may have special requirements when a spouse waives inheritance rights as a surviving spouse under probate law. For instance, Florida requires that the written agreement must be signed in front of two witnesses. Also, when it's a part of a postnuptial agreement, the spouses must have disclosed to each other the full extent of their estates. (Fla. Stat. § 732.702 (2024).)

What Postnuptial Agreements Can and Can't Do

Typically, spouses may use postnups to agree on how they'll handle certain financial issues during their marriage and when they divorce or one of them dies.

• Property and debts. Usually, postnups may address how a couple's property and debts will be divided in a future divorce. For example, spouses may agree that each of them will keep their own earnings and assets as separate rather than marital property, and that they'll each be responsible for their own debts. However, not all states allow couples to use postnuptial agreements to allocate their property rights in divorce. For instance, the Nebraska Supreme Court has held that these agreements aren't enforceable unless a couple signed them when they were separating or divorcing. In that situation, the agreement would more properly be considered a separation agreement or divorce settlement agreement, rather than a postnuptial agreement. (Devney v. Devney, 886 N.W.2d 61 (Neb. 2016).)
• Alimony. For example, both spouses might waive their right to seek spousal support if they get divorced. Or they might instead agree that one of them will pay a certain amount of alimony after divorce. However, a judge might decide not to enforce their agreement if, by the time of the divorce, it has become egregiously unfair because of changed circumstances. (Newman v. Newman, 653 P.2d 728 (Colo. 1982).)
• Inheritance rights. Spouses may agree to waive their right to inherit from each other after one of them dies.

Although couples may want to include other things in a postnuptial agreement, judges may not enforce provisions dealing with issues such as:

• Child custody. When parents separate or divorce, a judge will have to approve any agreements they've made about how they'll handle child custody, to ensure that the agreement is in the children's best interests. But the circumstances that go into what's best for children can change over time. So judges will look at the current circumstances when making custody decisions rather than accept agreements in a postnup the parents made before they were splitting up.
• Child Support. All states have guidelines for calculating child support, based largely on current parental income. And even though parents may agree on an amount of support that's higher or lower than the standard calculation, a judge won't approve their agreement unless the guideline amount would be unfair or inappropriate, based on the current circumstances. As a result, any provision in a postnuptial agreement about future child support will probably not be enforceable in the parents' later divorce.
• Performance of normal marital duties. Judges normally won't enforce provisions in postnuptial agreements dealing with issues like how spouses will divide up their household duties or other marriage responsibilities. In one California case, for instance, a married couple agreed that the husband would leave certain property to the wife in exchange for her promise to take care of him at home after a stroke. After the husband died without leaving her the property in his will, the court refused to enforce the agreement. As the court held, the wife's promise to care for her husband—which is included in the support duties that spouses owe each other—couldn't be considered consideration for the property transfer. (Borelli v. Borelli, 12 Cal.App.4th 647 (Cal. Ct. App. 1993).)

In some states, the laws spell out specific provisions in postnuptial agreements that aren't enforceable. Under Colorado law, for example, unenforceable provisions include those that penalize one spouse for filing for divorce or restrict any legal remedies for victims of domestic violence. (Colo. Rev. Stat. § 14-2-310 (2024).)

Why Sign a Postnup: Pros and Cons

Couples may decide to sign a marital agreement for various reasons, including when:

• they want to protect one spouse from the other spouse's debts, such as substantial medical debts, student loans, or even gambling debts
• a spouse who's leaving the workforce to focus on raising their children wants financial protections if the marriage ends
• a spouse who runs a business or professional practice wants to ensure that it won't be divided in a divorce
• they've gotten a pet and want to clarify what will happen to the animal if they split up
• a spouse with children from a previous marriage wants to protect their financial interests in the event of divorce or death, or
• the couple had a prenup, but now they want a new agreement because their financial circumstances have changed.

There are both pros and cons to signing a postnuptial agreement. On the plus side, a postnup can provide an opportunity for couples to get clear about their financial expectations. And if they've been experiencing serious problems in their marriage, a postnup might give the spouse who feels wronged a reason to give reconciliation a serious try.

Among the potential risks or downsides to postnups:

• If the spouses have unequal power in the relationship, there's a risk that one of them will feel pressured to give up financial and legal rights in a postnup.
• As discussed above, judges tend to scrutinize marital agreements carefully. Also, the laws about postnups aren't clear in some states. As a result, it can be difficult to anticipate whether a judge will enforce an agreement.

Enforcing—or Challenging—a Postnuptial Agreement

If you're getting divorced and are hoping to challenge any provisions in your postnup, the judge will first look at whether the agreement meets your state's requirements for the validity of these agreements (as discussed above). For instance, you might argue that your spouse hid important assets, lied about the value of a family business, or coerced you into signing an agreement that's so unfair it would be considered unconscionable.

Similarly, if you're asking a judge to enforce a marital agreement that your spouse is challenging, the result will depend on the laws (and court decisions) in your state, as well as the strength of the evidence you can provide.

Do You Need a Lawyer for a Postnuptial Agreement?

As discussed above, postnuptial agreements won't be considered valid in some states if both spouses didn't have separate lawyers (or didn't have the chance to consult with an attorney) when they signed the agreement. But even if that's not the law in your state, it's risky to sign an agreement without consulting with a lawyer. An experienced family law attorney can explain your state's requirements for postnuptial agreements and help you write one that meets those requirements and is fair to both you and your spouse. At the very least—for instance, if your spouse has presented you with a draft agreement—you should have an independent lawyer (not your spouse's attorney) review it before you sign.