Is Your Prenup Ironclad? Challenging and Enforcing Agreements in NY

A prenuptial agreement can be one of the most powerful tools for protecting your financial future, but only if it stands up in court. In New York, even small technical errors or procedural missteps can render an agreement invalid. From missing acknowledgments to unclear financial disclosures, what may seem like a “simple contract” can quickly unravel under judicial scrutiny. 

If you are facing a divorce or considering a prenup, the guidance of a Manhattan divorce lawyer who understands New York’s strict requirements is critical. The courts take a hard line on both form and fairness, and a well-prepared strategy can make the difference between enforcement and invalidation. For trusted, experienced counsel, contact The Law Office of Richard Roman Shum, Esq. at (646) 259-3416 to schedule a confidential consultation and ensure your rights are fully protected.

New York’s Strict Formalities (DRL § 236(B)(3))

Before a court will even consider the contents of a prenuptial agreement, it first acts as a gatekeeper, ensuring the document meets New York’s exacting statutory requirements. The controlling law, New York Domestic Relations Law (DRL) § 236(B)(3), sets forth three absolute, non-negotiable conditions for a valid and enforceable agreement:

• It must be in writing. A verbal prenuptial agreement carries no legal weight in New York. Oral promises or “understandings” are meaningless unless turned into writing.
• It must be subscribed by both parties. Each party must sign (“subscribe”) to the agreement. The statute does not require the signatures to appear at the very end, only that both parties have signed the written instrument.
• It must be acknowledged or proven in the manner required to entitle a deed to be recorded. This final requirement is often the fatal flaw. It is a highly technical formality, but it is also the most litigated and the one that has destroyed countless otherwise fair agreements.

Why “Acknowledgment” Is Not the Same as “Notarization”

Many people casually refer to a prenup being “notarized.” But the statute demands far more. The acknowledgment requirement, borrowed from New York’s Real Property Law, is precise, procedural, and unforgiving.

A proper acknowledgment requires two distinct steps:

• The signer must appear before the notary (or other authorized officer) and orally acknowledge that they are the person named in the agreement and that they signed it voluntarily.
• The notary must then execute a proper certificate of acknowledgment, which must be in substantial compliance with the Real Property Law. This certificate must affirm that the notary “knows or has satisfactory evidence that the person making it is the person described in and who executed such instrument.”

If either step is missing or even worded improperly, the acknowledgment fails.

The Courts Have Strict Tolerance for Technical Defects

New York’s highest court has long enforced these formalities strictly, but more recent cases recognize limited flexibility. The safest practice remains to ensure every acknowledgment certificate strictly tracks the statutory language.

Matisoff v. Dobi (90 N.Y.2d 127)

The parties had a postnuptial agreement that was signed but never acknowledged. Even though both admitted in court that they had signed it, the Court of Appeals declared it unenforceable, period. The court held that the acknowledgment requirement is a legislative mandate, not a mere formality that can be excused or waived.

Galetta v. Galetta (21 N.Y.3d 186)

Here, the prenup was signed and notarized, but the notary’s certificate for the husband was missing one critical phrase confirming that the notary “knew or had satisfactory evidence” of the signer’s identity. That omission, though seemingly minor, was fatal. The Court of Appeals invalidated the entire agreement years later, even though the omission seemed minor, demonstrating how technical acknowledgment errors can still be fatal if not properly executed.

Before an attorney ever analyzes provisions on property division or spousal maintenance, they must examine the acknowledgment certificates. If the acknowledgment is defective or missing altogether, the inquiry stops there. The prenuptial agreement is unenforceable, regardless of its fairness or the parties’ intent.

Manhattan Divorce Lawyer Richard Roman Shum, Esq.

The Main Grounds for Challenging a Valid Prenup

Once a prenuptial agreement passes the strict formal requirements, the focus shifts from form to substance. The battle becomes one of fairness, consent, and disclosure. Under New York law, the party seeking to overturn a validly executed prenup bears a heavy burden of proof. To succeed, they must establish one or more recognized grounds for invalidation.

Fraud and Failure of Financial Disclosure

Although full and fair financial disclosure is best practice and strongly considered by courts, New York law does not automatically void a validly executed prenuptial agreement for incomplete disclosure. Only intentional concealment or misrepresentation, fraud, or overreach can justify setting it aside.

This is not about simple mistakes or minor omissions. Fraud involves intentional deception, such as hiding offshore accounts, falsifying business valuations, or failing to disclose significant liabilities. The law is clear: a person cannot knowingly waive rights to assets or interests that were never disclosed to them.

Duress, Coercion, and Undue Influence

Allegations of duress or coercion are common but notoriously difficult to prove. The legal standard for duress in New York is very high. It requires showing that the challenger was subjected to threats, violence, or other forms of pressure so severe that they had no reasonable alternative but to sign.

Merely feeling pressured, anxious, or regretful is not enough. New York courts have repeatedly ruled that a threat to call off the wedding by itself does not constitute legal duress. While courts will consider the timing of the signing, such as a last-minute presentation of the agreement, it is only one factor among many.

A successful claim usually involves a pattern of coercive behavior. For instance, a court might find duress if the prenup was presented just days before the wedding, the spouse had no independent attorney, was financially dependent on the other party, and the terms were dramatically one-sided. Only when these elements converge does the court find genuine coercion or undue influence.

Unconscionability and Overreaching

Perhaps the most nuanced and powerful ground for challenge is unconscionability, which is the notion that an agreement is so one-sided that it offends basic fairness. New York courts recognize that prospective spouses do not negotiate as strangers at arm’s length; they share a confidential and fiduciary relationship.

In Christian v. Christian (42 N.Y.2d 63), the Court of Appeals held that courts must “throw their cloak of protection” over prenuptial agreements to ensure they are entered into fairly and equitably, free from fraud or duress.

However, the standard is not mere inequality or a bad bargain. To invalidate an agreement, the disparity must be so extreme and shocking that “no person in their senses and not under delusion would make it, and no honest and fair person would accept it.” The unfairness must be manifest and substantial, so much so that it “shocks the conscience.”

In practice, successful challenges under this ground rarely rest on a single defect. They rely on a cumulative narrative of overreaching, for example, where a party failed to make full disclosure, manipulated the negotiation process, delayed the signing, and included grossly disproportionate terms. Courts view these combined factors as evidence of overreaching, the very abuse that Christian v. Christian sought to prevent.

Spousal Maintenance (Alimony) Waivers

Clauses concerning spousal maintenance (alimony) receive special scrutiny under DRL § 236(B)(3). 

Courts apply a two-step analysis. First, they assess whether the waiver was fair and reasonable when signed. Second, they take a “second look” at the time of divorce to ensure that enforcing the waiver would not be unconscionable or leave one spouse unable to support themselves 

This second review provides critical protection. Even if a waiver was perfectly fair when signed, it may later be struck down if enforcing it would leave one spouse unable to support themselves or at risk of becoming a public charge.

This dynamic test ensures that prenuptial agreements remain equitable over time, reflecting both the parties’ intent and their changing circumstances.

Ground	What must be shown	Key statute or case law
Fraud and Failure of Financial Disclosure	Intentional concealment or misrepresentation of significant assets or liabilities. Minor errors are not enough.	Christian v. Christian (42 N.Y.2d 63)
Duress, Coercion, and Undue Influence	Agreement was signed under serious pressure or threats. Feeling anxious or pressured isn’t enough.	High burden of proof under New York law
Unconscionability and Overreaching	Terms are so unfair that they shock the conscience. Often involves poor disclosure or manipulation.	Christian v. Christian standard
Spousal Maintenance (Alimony) Waivers	Waiver must have been fair when signed and remain fair at the time of divorce.	DRL § 236(B)(3)

A Loophole in Spousal Support Waivers

The law on prenuptial agreements continues to evolve. A 2025 case from Kings County Supreme Court has introduced a new way to challenge maintenance (alimony) waivers, exposing a potential weakness in many existing agreements.

In J.M. v. G.V. (2025 NY Slip Op 25004), the court addressed a question of first impression:

Must a self-represented spouse receive the presumptive spousal maintenance calculations to make a knowing waiver of those rights?

The court’s answer was yes.

The parties had signed a prenuptial agreement one week before the wedding. The wife had counsel; the husband did not. The agreement included a standard waiver of spousal maintenance. After reviewing Domestic Relations Law § 236, the court concluded that a waiver is only “knowing” if the person understands the actual value of the right being waived.

The court held that for a maintenance waiver to be valid, especially when one party is unrepresented, the agreement must include the full presumptive maintenance calculations, including both parties’ incomes and the computed guideline amount as of the signing date. A simple clause such as “I waive all maintenance” is no longer sufficient.

This decision could affect many prenuptial agreements in New York. It turns the maintenance guidelines into a required disclosure during drafting, not just a tool for divorce proceedings. Attorneys preparing or reviewing prenups must now ensure that any maintenance waiver includes these calculations to protect the agreement’s enforceability.

Enforcing Your Agreement: How to Defend Your Prenup

If you are the party seeking to enforce a prenuptial agreement, your strategy is different. Your goal is to preserve the strong presumption of validity that New York law gives these agreements and to prevent your spouse from meeting their very high burden of proof.

Your attorney’s first task is to introduce the agreement into the divorce proceeding and show that it is facially valid. This means proving that the agreement is in writing, signed by both parties, and includes acknowledgment certificates that comply with the standards set in Galetta v. Galetta.

Once these elements are established, the burden shifts to your spouse. They must then prove, through specific facts, that some unfairness or misconduct occurred that justifies setting the agreement aside. Courts describe this as showing a “particularized inequality.”

Defeating the “Shifting Burden”

A common tactic used by challengers is to try to shift the burden of proof. In Matter of Greiff (92 N.Y.2d 341), the Court of Appeals recognized that in rare cases, the special relationship between engaged couples could justify shifting this burden.

Under the Greiff standard, if the challenger proves by a preponderance of the evidence that the circumstances suggest probable undue or unfair advantage, the burden flips. At that point, the party defending the agreement must prove that it was entered into freely, fairly, and without fraud or coercion.

This motion often determines the outcome of the case. The defense depends on whether the negotiation process was fair and transparent. The best way to defeat a Greiff challenge is to show that the agreement was created through a clear, fair, and well-documented process.

Building a Bulletproof Defense

A strong defense of your prenuptial agreement relies on proof that the negotiation was fair and informed. The following factors are your best protection against claims of overreaching or coercion:

• Independent Legal Representation: This is the most important safeguard. If your spouse had their own attorney, it is very difficult for them to claim later they were coerced, misled, or did not understand the agreement.
• Full Financial Disclosure: Your defense should include complete and accurate financial disclosures attached to the agreement. Courts give significant weight to signed and acknowledged financial schedules.
• Adequate Timing and Negotiation: The record should show that the agreement was provided well before the wedding and that there was time for review. Evidence of ongoing discussions, negotiations, or exchanged drafts between attorneys supports fairness and defeats any claim that it was a “take it or leave it” situation.

Skilled Representation Matters in Prenup Cases

A prenuptial agreement is more than a financial plan; it is a reflection of trust and foresight. Yet in New York, even the most carefully drafted agreement can fail if it does not meet the state’s strict technical and fairness standards. Whether you are preparing, reviewing, or enforcing a prenup, the process demands precision and legal experience.

As New York courts continue to refine how these agreements are interpreted, having a knowledgeable attorney by your side is essential. Speak with The Law Office of Richard Roman Shum, Esq. today at (646) 259-3416 to discuss your situation in confidence. An experienced Manhattan divorce lawyer can help you understand your options and secure an agreement that truly protects your interests.