Are Postnuptial Agreements Enforceable in Long Island, New York?

If you’re married and trying to protect your financial interests, you may be wondering, are postnuptial agreements enforceable in Long Island, New York? This is a common concern, especially for couples who didn’t sign a prenuptial agreement but now face changing financial circumstances.

Whether you’ve received a large inheritance, merged assets through a joint account, or started to define what’s yours and what belongs to the other spouse, a postnuptial agreement can offer a clearer path forward. But under New York law, not every postnuptial agreement is enforceable. If the agreement isn’t properly structured or fails to meet certain legal requirements, it could be set aside during divorce proceedings.

This blog explains how New York courts treat postnuptial agreements, what makes them valid, and the factors that could lead a judge to invalidate one.

What Is a Postnuptial Agreement in New York?

A postnuptial agreement is a legal contract made between married couples that defines how assets, debts, and financial support will be handled in the event of a divorce or the death of one spouse. Unlike prenuptial agreements, which are signed before marriage, postnuptial agreements are signed after you’re already married.

In New York, postnuptial agreements are considered a type of marital agreement and must follow specific rules to be valid under the law.

Legal Requirements for a Valid Postnuptial Agreement

To be enforceable in New York, your postnuptial agreement must meet certain standards. The courts won’t automatically uphold an agreement just because both spouses signed it.

Here’s what New York courts generally look for:

• Full and fair disclosure of each spouse’s financial circumstances at the time of the agreement
• The agreement must be in writing and signed by both spouses
• The signatures must be acknowledged before a notary public
• The agreement must not be unconscionable (grossly unfair) to one spouse
• Both you and your spouse should ideally have separate attorneys, though it is not required by New York law

Although Domestic Relations Law § 236(B)(3) does not use the word “postnuptial,” it applies to any agreement made “before or during the marriage,” which courts interpret to include postnuptial agreements.

If any of these elements are missing or questionable, the agreement may be challenged and declared invalid during the divorce process.

What a Postnuptial Agreement Can Cover

A well-drafted postnuptial agreement can address many aspects of your financial life. For married couples in Long Island, these agreements are often used to:

• Define marital property vs. separate property
• Allocate property division in the event of a divorce
• Protect a significant amount of assets from a previous marriage
• Outline spousal support obligations
• Preserve inheritance rights for children from a prior relationship

By clearly defining separate property, such as a business, inheritance, or real estate, you reduce the likelihood of future disputes. For example, you can specifically identify real estate, a family business, or retirement accounts as separate property if you don’t want them to be considered marital property.

When a Postnuptial Agreement Might Be Invalid

Even if you follow the formal requirements, there are still situations where a court might rule the postnuptial agreement unenforceable. Here are a few common issues that can lead to problems:

• Lack of full and fair disclosure at the time of signing
• One spouse was coerced or signed under pressure
• The agreement was grossly one-sided and unfair to one spouse
• The terms attempt to waive child support or interfere with child custody, which violates public policy

For example, if one spouse hides significant debts or assets and the other signs without knowing, the court may decide the agreement is invalid. The same goes if a spouse unfairly pressures the other into signing without legal advice.

Can a Postnuptial Agreement Address Child Support or Custody?

No. Under New York law, you cannot waive or predetermine child support or child custody terms in a postnuptial agreement. These matters are always decided based on the child’s best interests at the time of the divorce.

Even if both you and your spouse agree to a specific custody or support arrangement in the agreement, the court is not bound by those terms. The judge will consider what works best for the child based on the circumstances at the time of separation.

Benefits of a Postnuptial Agreement in Long Island

While postnuptial agreements are not right for every couple, they can bring significant benefits in the right situations. You might want to consider one if:

• You or your spouse owns a business
• You received a large inheritance and want to keep it separate
• There’s been a change in financial stability or financial support
• One or both of you has children from a previous marriage
• You and your spouse want to update your financial arrangements without ending the marriage

In some cases, signing a postnuptial agreement can even help preserve a troubled marriage by reducing financial tension and outlining clear expectations moving forward.

Why You and Your Spouse Should Use Separate Attorneys

One of the most common reasons a postnuptial agreement is later invalidated by the court is because one spouse didn’t fully understand what they were signing. That’s why it’s always better for both you and your spouse to have a separate postnuptial agreement lawyer. This helps protect the agreement from claims of duress, coercion, or unfairness.

A postnuptial agreement lawyer can review the terms with you, explain what you’re giving up or gaining, and help you assess whether it’s in your long-term financial interests. If your spouse agrees to terms without understanding the impact, that can raise red flags during divorce proceedings.

Postnuptial Agreements and Estate Planning

These agreements are not only used in the event of divorce. They can also help protect assets if your spouse dies. In Long Island, many couples also use postnuptial agreements as part of a broader estate plan, especially when there are children from prior relationships or significant separate assets involved.

If you want to keep such property out of probate or avoid conflicts between family members, clearly defined postnuptial agreements can work alongside your will or trust.

Protect What You’ve Built. Talk to a Long Island Postnuptial Agreement Lawyer Today

Whether you’re updating your financial plans, preserving separate property, or addressing concerns in your marriage, the Long Island family law lawyers at Hedayati Law Group, P.C. can help you draft or review a postnuptial agreement that reflects your goals. Since 2009, we’ve advised married couples across Suffolk County, Nassau County, and New York City on property division, spousal support, and marital agreements with long-term stability in mind.

With over 150 years of combined legal experience, our team brings a strong background in finance, litigation, and family law to every case. We understand the sensitive nature of postnuptial agreements and work to protect your interests while reducing the risk of future legal disputes.

If you’re searching for a “postnup lawyer near me” who understands both the legal and financial impact of these agreements, we’re ready to help. When you work with us, we take the time to understand your situation, explain your options, and develop a strategy that supports your financial future, whether you’re staying married or preparing for the possibility of divorce.

Call us at (516) 334-4100(516) 334-4100 or fill out our confidential online form to schedule your free consultation with a postnuptial agreement attorney. We’re here to help you move forward with confidence.

We’re here to protect your rights so you can move forward on your terms.

Copyright © 2025. Hedayati Law Group, P.C.  All rights reserved.

The information in this blog post (“post”) is provided for general informational purposes only and may not reflect the current law in your jurisdiction. No information in this post should be construed as legal advice from the individual author or the law firm, nor is it intended to be a substitute for legal counsel on any subject matter. No reader of this post should act or refrain from acting based on any information included in or accessible through this post without seeking the appropriate legal or other professional advice on the particular facts and circumstances at issue from a lawyer licensed in the recipient’s state, country, or other appropriate licensing jurisdiction.

Hedayati Law Group, P.C.
666 Old Country Road, Suite 444
Garden City, NY 11530
(516) 334-4100(516) 334-4100
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