Postnuptial Agreements Guide

A postnuptial agreement is a legal contract between spouses that establishes how assets, debts, and financial matters will be handled in the event of divorce or death. It works much like a prenuptial agreement, with one critical difference: a postnup is signed after the marriage has already taken place, not before.

Postnuptial agreements are recognized in the majority of states, though the rules governing their enforceability vary. They are becoming increasingly common as couples recognize that financial circumstances, priorities, and risks change during a marriage. Whether you are addressing new wealth, recovering from infidelity, or simply planning ahead, a postnup can provide clarity and protection for both spouses.

What a Postnuptial Agreement Covers

A postnuptial agreement can address most of the same financial issues as a prenup. Common provisions include:

Property division. The agreement can specify which assets are marital property (subject to division in divorce) and which are separate property (retained by one spouse). This is particularly useful when one spouse receives an inheritance, starts a business, or acquires significant assets during the marriage.

Debt allocation. A postnup can establish that debts incurred by one spouse — such as business loans or student loans taken on during the marriage — remain that spouse’s responsibility.

Spousal support. The agreement can set the terms of alimony, including the amount, duration, and conditions for modification or termination. Some couples agree to waive alimony entirely; others establish a specific formula.

Business interests. If one or both spouses own a business, a postnup can protect the business from division in divorce, specify how it will be valued, or establish a buyout arrangement.

Estate planning coordination. A postnup can work alongside wills and trusts to ensure that each spouse’s estate plan is consistent with the marital agreement.

Financial responsibilities during the marriage. Some postnups address how household expenses, savings, and investments will be managed during the marriage, not just in the event of divorce.

A postnuptial agreement cannot include provisions about child custody or child support. Courts decide these issues based on the child’s best interests at the time of divorce, and parents cannot contractually determine them in advance.

How Postnups Differ from Prenups

The fundamental difference is timing: prenups are signed before the wedding, postnups after. But this timing difference creates several practical and legal distinctions.

Enforceability standards. Courts scrutinize postnups more carefully than prenups because of the fiduciary duty that exists between spouses. Married couples owe each other duties of good faith and full disclosure that engaged couples may not. This means courts are more likely to invalidate a postnup if there was inadequate disclosure or if the terms are significantly one-sided.

Bargaining dynamics. Before marriage, each party is negotiating at arm’s length. After marriage, the dynamics are different — one spouse may feel pressure to sign because the other threatens divorce, or the agreement may be proposed during a period of marital stress when one spouse has less bargaining power.

Consideration. Contracts require consideration (something of value exchanged). For prenups, the marriage itself is the consideration. For postnups, courts may require additional consideration — a mutual promise, a specific benefit exchanged, or the agreement itself serving as consideration for the continuation of the marriage.

State recognition. While nearly all states recognize prenuptial agreements, a few states have historically been reluctant to enforce postnuptial agreements. Ohio, for example, has been more cautious, though the trend nationally is toward broader acceptance.

For detailed information on prenuptial agreements, see our guide on prenuptial agreements.

Reasons to Get a Postnuptial Agreement

Couples pursue postnups for a wide range of reasons. Some of the most common include:

They did not get a prenup. Many couples do not think about a prenup before the wedding — or they feel uncomfortable bringing it up. A postnup addresses the same concerns after marriage.

Financial circumstances have changed. A spouse received a large inheritance, started a successful business, or came into significant wealth during the marriage. A postnup can clarify that these assets remain separate property.

Marital difficulties. Some couples use a postnup as part of reconciliation after infidelity or other marital problems. The agreement can include provisions that incentivize commitment — for example, more favorable alimony terms for the spouse who was wronged if the marriage later ends.

Career changes. When one spouse leaves the workforce to raise children or support the other spouse’s career, a postnup can ensure they are protected financially if the marriage ends.

Blended families. Spouses with children from prior relationships may want to ensure that certain assets are preserved for those children rather than being divided in a potential future divorce.

Business protection. A spouse who starts or grows a business during the marriage may want to establish the terms for valuing and dividing (or not dividing) the business interest.

Debt protection. When one spouse takes on significant debt — for a business venture, for example — the other spouse may want a postnup to shield their assets from those liabilities.

Enforceability

Not all postnuptial agreements hold up in court. To maximize the likelihood that a postnup will be enforced, both spouses should ensure the following:

Full financial disclosure. Both spouses must provide complete, honest disclosure of all assets, debts, income, and financial obligations. Hiding or underestimating assets is the most common reason postnups are invalidated.

Independent legal counsel. Each spouse should have their own attorney review and advise on the agreement. If only one spouse has legal representation, a court may find that the other spouse did not understand what they were signing.

Voluntary execution. Neither spouse can be coerced or pressured into signing. Threats of divorce, emotional manipulation, or signing during a crisis can all be grounds for invalidation.

Reasonable terms. An agreement that leaves one spouse destitute while the other retains all assets is unlikely to be enforced. Courts expect the terms to be fair — or at least not unconscionably one-sided.

Proper formalities. The agreement must be in writing, signed by both spouses, and in some states, notarized or witnessed.

No provisions regarding children. Including child custody or child support terms can jeopardize the entire agreement. Keep these issues separate.

Cost of a Postnuptial Agreement

The cost of a postnuptial agreement varies depending on the complexity of the couple’s finances and the attorneys’ rates. Typical ranges:

• Simple postnup (straightforward finances, few assets): $2,500 to $5,000 per spouse for attorney fees
• Moderate complexity (business interests, significant assets, or real estate): $5,000 to $10,000 per spouse
• High complexity (multiple business interests, substantial wealth, or multi-state considerations): $10,000 to $25,000 or more per spouse

Because each spouse needs independent counsel, the total cost is at least double the per-spouse amount. While this may seem expensive, it is a fraction of the cost of litigating property division and alimony in a contested divorce, which can easily exceed $50,000 to $100,000 per spouse.

Common Misconceptions

Several myths about postnuptial agreements persist. Here are the facts:

“A postnup means we are planning to divorce.” Many couples who sign postnups have no intention of divorcing. They are planning for a possibility, just as people buy insurance without expecting a disaster. In fact, having clear financial expectations can reduce conflict and strengthen a marriage.

“A postnup is only for wealthy couples.” Couples at any income level can benefit. A postnup can protect a small business, allocate student loan debt, or clarify financial responsibilities in a way that prevents disputes.

“A postnup is always enforceable.” It is not. Courts can and do invalidate postnuptial agreements that were signed under duress, without full disclosure, or with unconscionably unfair terms.

“We can write our own postnup.” While there is no law against drafting your own agreement, a DIY postnup is far more likely to be invalidated. The investment in legal counsel is essential for an agreement that will actually hold up in court.

“A postnup covers child custody.” It does not. Courts will not enforce custody or child support provisions in a marital agreement. These decisions must be made at the time of divorce based on the child’s circumstances.

For context on how divorce and property division work more broadly, see our complete guide to divorce.

What to Do Next

If you are considering a postnuptial agreement, take these steps:

1. Discuss the idea with your spouse. Frame the conversation around mutual protection and financial clarity rather than distrust. Many couples find that the process of creating a postnup improves their financial communication.
2. Compile your financial information. Gather complete records of all assets, debts, income, and financial obligations for both spouses. Full disclosure is essential to enforceability.
3. Hire separate attorneys. Each spouse must have independent legal counsel. Do not use the same attorney — this creates a conflict of interest and may invalidate the agreement.
4. Take your time. Do not rush the process. Allow adequate time for both spouses to review, ask questions, and negotiate terms. An agreement signed in haste is more vulnerable to challenge.
5. Consult with a family law attorney. If you are unsure whether a postnup is right for your situation, schedule a consultation to discuss your options and understand how postnuptial agreements work in your state.

Frequently Asked Questions

How is a postnuptial agreement different from a prenup?

The fundamental difference is timing: a prenup is signed before the wedding, while a postnup is signed after. This creates additional legal complexity because married couples owe each other fiduciary duties of good faith and full disclosure. Courts scrutinize postnups more strictly, and some states require additional consideration beyond the marriage itself to make the contract valid.

Can a postnuptial agreement address infidelity or marital reconciliation?

Yes. Some couples use a postnup as part of reconciliation after infidelity, including provisions that provide more favorable alimony or property terms for the wronged spouse if the marriage later ends. These provisions are enforceable in many states as long as the overall agreement meets standard requirements for voluntariness and disclosure.

Are postnuptial agreements enforceable in every state?

The majority of states recognize postnuptial agreements, but a few have historically been reluctant to enforce them. Even in states that do recognize postnups, courts apply stricter scrutiny than they do to prenups. Both spouses must have independent legal counsel, provide full financial disclosure, and sign voluntarily. An agreement that is significantly one-sided is more likely to be invalidated.

How much does a postnuptial agreement cost?

Costs range from $2,500 to $5,000 per spouse for a straightforward postnup to $10,000 to $25,000 or more per spouse for complex situations involving business interests or substantial wealth. Because each spouse needs independent counsel, the total cost is at least double the per-spouse amount. This is still a fraction of the cost of litigating the same issues in a contested divorce.

How This Guide Was Researched

This guide was created by reviewing publicly available legal information from official state statutes, judiciary websites, court resources, and family law publications. The goal is to explain family law topics in plain English so readers can better understand the process before speaking with an attorney.

Sources and Legal References

This guide is based on publicly available legal information and official sources, including:

• Premarital and Marital Agreements Act – Uniform Law Commission
• Marital Settlement Agreement – Legal Information Institute
• Prenuptial Agreement – Legal Information Institute
• Marital Property – Legal Information Institute
• ABA Family Law Section Resources

For more about how we research our guides, see our editorial policy and sources methodology.

Related Guides

Learn more about related family law topics:

• Divorce checklist
• Property division in divorce
• How to file for divorce
• Complete guide to divorce
• Dividing retirement accounts in divorce

Last updated: March 2026. This guide summarizes general legal information based on publicly available sources and is provided for educational purposes only. It does not constitute legal advice. For advice specific to your situation, consult a licensed attorney in your state.