What Makes a Prenup Invalid in Florida?

1. What Makes a Prenup Legal and Valid in Florida?

The formal test is short. A Florida premarital agreement has to be in writing and signed by both people, and the marriage itself is the only consideration the agreement needs. Nothing has to be paid or promised on top. The agreement takes effect on the wedding day, and from then on it can be changed or cancelled only by another written agreement signed by both spouses.

Florida does not require a notary, a filing with the clerk, or a minimum waiting period before the wedding. Couples are often surprised by how little the statute demands, and the low bar is the reason most fights are about how the agreement was signed rather than what it says.

One formality gets missed all the time. A prenup that waives rights at death, such as the elective share or homestead, is governed for that purpose by the probate code, and the probate code requires the waiving spouse to sign in front of two subscribing witnesses when the agreement is signed by Florida residents. An agreement with two signatures and no witnesses can be perfectly good in a divorce and still fail to deliver the estate result the couple wanted. How a prenup works at death covers that side in full.

2. What Voids a Prenup? The Three Grounds Florida Allows

In a divorce, Florida’s premarital act puts the burden on the spouse who wants out. The agreement is unenforceable only if that spouse proves one of these.

1. The signature was not voluntary. The person did not freely choose to sign.
2. Fraud, duress, coercion or overreaching produced it. A lie about the agreement or the finances, a threat, or one side taking unfair advantage of the other.
3. The terms were unconscionable when signed, and the disclosure failed. All of the disclosure conditions in the next section have to be missing too.

The first two grounds are about the circumstances of signing. The statute names no deadline before the wedding, so a signature in the final week does not void an agreement by itself. A late signature is still the fact a duress or overreaching argument gets built on, because the other person can say the venue was booked, the guests had flights, and walking away was not a real option.

Most of the agreements that fall, fall on those first two grounds. A spouse who can prove pressure at signing never has to argue about whether the terms were fair.

3. Unconscionable Terms and the Disclosure Test

Unfair terms alone do not void a Florida prenup. The third ground needs four things together. The terms were unconscionable when the agreement was signed, and before signing the challenger also lacked all three of the following protections.

• was not given a fair and reasonable disclosure of the other person’s property and debts,
• did not voluntarily and expressly waive, in writing, any disclosure beyond what was provided, and
• did not have, and could not reasonably have had, adequate knowledge of the other person’s finances.

If any one of those conditions is met, the one-sided agreement survives. A wife who signed a lopsided agreement after seeing a schedule of her husband’s $2.4 million in accounts is bound by it. So is a husband who signed a written waiver of further disclosure, and so is a spouse who already knew the other’s finances from years of running a business together. Whether terms are unconscionable at all is decided by the judge as a matter of law rather than by a jury.

The practical lesson is that the disclosure schedule protects the spouse with more money. Attaching it costs an afternoon, and leaving it off turns a hard bargain into a vulnerable one.

4. A Challenge After a Death Runs on Different Rules

Florida’s premarital act says in its first subsection that it applies only to proceedings under the Family Law Rules. The three grounds above are therefore the divorce test. When a spouse dies and the survivor tries to claim the elective share, homestead or a family allowance despite the agreement, the fight happens in probate court under a different statute.

The probate statute changes two things. The waiving spouse must have signed in front of two subscribing witnesses if the agreement was signed in Florida by Florida residents. And no financial disclosure is required at all for an agreement signed before the marriage. Disclosure is required only for a waiver signed after the wedding, which is why a postnuptial agreement carries more paperwork than a prenup.

The right to set the agreement aside still exists at death. The Florida Supreme Court has said a surviving spouse can attack the agreement if the signature was coerced or otherwise improperly obtained, or if the spouse was incompetent when signing. What the survivor cannot do is win on the argument that nobody showed her the numbers.

5. Terms a Florida Court Will Not Enforce Anyway

A few provisions fail no matter how carefully the agreement was signed, and they fail on their own without taking the rest of the agreement down with them in the ordinary case.

• Child support. A premarital agreement cannot adversely affect a child’s right to support. Custody and time-sharing are decided later by the child’s best interests.
• An alimony waiver that leaves a spouse on public assistance. If the waiver would make a spouse eligible for public assistance at the separation or divorce, the court can order the other spouse to pay enough support to avoid that.
• A void marriage. If the marriage itself is later found void, the agreement is enforced only to the extent needed to avoid an inequitable result.
• Anything against public policy or a criminal law. Everything else is open, including property, debts, alimony, life insurance and what happens at death. What a prenup can cover walks through the full list.

6. Can You Challenge a Prenup, and When?

Yes. A Florida prenup can be challenged in the divorce itself, by the spouse against whom it is being enforced, and it can be challenged in probate after a death by a surviving spouse who claims rights the agreement waived.

Timing works in the challenger’s favor and against it at once. Florida pauses any limitation period on a claim under a premarital agreement for as long as the marriage lasts, so nobody loses the right to raise it by waiting through a long marriage. The same statute keeps laches and estoppel available to either side, which means years of living under the agreement and accepting its benefits can still be used against the spouse who now wants out.

The person defending the agreement also has work to do. The disclosure schedule, the drafts that passed between two lawyers, the date of signing and the identity of the witnesses are the evidence that answers a challenge. Agreements fall most often when those records were never kept.

Challenging or defending an agreement is litigation. Kevin litigates probate and trust disputes, including fights over spousal waivers after a death, and that work is quoted per matter rather than at a flat fee. See probate litigation.

7. How to Make a Prenup Legal and Hard to Challenge

Each step below answers one of the grounds a challenger would raise.

1. Sign early. An agreement signed two or three months before the wedding is hard to describe as coerced. See how to get a prenup in Florida for the timeline.
2. Attach a real disclosure from each side. Account balances, real estate, business interests and debts, with values and dates.
3. Add a written waiver of further disclosure. The statute names the waiver expressly, so a signed waiver closes the disclosure route even where a value was missed.
4. Give each person a separate lawyer. Florida does not require it, and a lawyer on each side is the strongest evidence that the signature was informed and voluntary.
5. Sign before two subscribing witnesses and a notary, and initial every page. The witnesses are required for the death-rights waiver when signed in Florida. The notary and initials cost nothing and make a swapped page or a disputed signature hard to claim.

What a New Agreement or a Challenge Costs

Drafting a new prenup or postnup is a flat fee quoted at consult, because the price turns on what has to be valued and disclosed and on whether a business, a trust interest or a blended family is involved. What a Florida prenup costs explains the range.

Challenging or defending an existing agreement in a divorce or a probate case is litigation and is quoted per matter. Nobody can price a lawsuit honestly before reading the agreement and the record of how it was signed, and we will not pretend otherwise. Government costs such as filing and recording fees are additional and passed through at cost.

Frequently Asked Questions

Common Situations

The agreement handed over at the rehearsal dinner. A bride receives a 30-page agreement two days before the wedding, with no schedule of her fiancé’s assets and no time to call a lawyer. She signs. Years later the agreement is exposed on the voluntariness ground and on the disclosure route at once, and the spouse who drafted it is the one who has to defend the circumstances.

The lopsided agreement with a full schedule. A husband gives up any claim to his wife’s medical practice, worth several times everything he owns. She attached a valuation and both had lawyers. He calls the terms unfair, and Florida answers that unfairness alone does not void an agreement the other person signed with the numbers in front of him.

The widow who never saw the accounts. A second wife signed a prenup waiving everything and was never told what her husband owned. After his death she argues she would not have signed with full information. Florida requires no disclosure for a waiver signed before the marriage, so her claim depends on proving coercion or incapacity at signing rather than ignorance.

Sources of Law

• Fla. Stat. §61.079 (Uniform Premarital Agreement Act). §61.079(1) (applies only to proceedings under the Florida Family Law Rules of Procedure); §61.079(3) (writing signed by both parties; enforceable without consideration other than the marriage); §61.079(4)(a)8. and (4)(b) (any matter not violating public policy or a criminal statute; a child’s right to support may not be adversely affected); §61.079(5) (effective upon marriage); §61.079(6) (amendment or revocation after marriage only by written agreement signed by the parties); §61.079(7)(a)1. to 3. (unenforceable if the party resisting enforcement proves the agreement was not executed voluntarily, was the product of fraud, duress, coercion, or overreaching, or was unconscionable when executed and the party was not provided fair and reasonable disclosure, did not voluntarily and expressly waive disclosure in writing, and did not have and reasonably could not have had adequate knowledge); §61.079(7)(b) (support despite waiver to avoid public-assistance eligibility); §61.079(7)(c) (unconscionability decided by the court as a matter of law); §61.079(8) (void marriage); §61.079(9) (limitation periods tolled during the marriage; laches and estoppel available); §61.079(10) (does not alter agreements under §§732.701 and 732.702). History, s. 1, ch. 2007-171.
• Fla. Stat. §732.702(1) (spousal rights at death may be waived before or after marriage by a written agreement signed by the waiving party in the presence of two subscribing witnesses, the witness requirement applying to instruments signed by Florida residents); §732.702(2) (fair disclosure required for an instrument executed after marriage; none required before marriage); §732.702(3) (no consideration beyond execution).
• Estate of Roberts, 388 So. 2d 216, 217 (Fla. 1980) (upholding §732.702(2), which removed the disclosure requirement of Del Vecchio v. Del Vecchio, 143 So. 2d 17 (Fla. 1962), for agreements signed before marriage, and noting that a challenge for coercion, an improperly obtained signature or incompetence at signing remains available). Opinion read in full.
• Statutes retrieved from flsenate.gov and the in-repo statute files on October 2, 2026.

The Detail That Decides These Cases

Trial work teaches you which sentence a lawyer on the other side will pull out and read to the judge, and in a prenup fight that sentence is almost never in the agreement. The sentence is in the story of how the agreement was signed.

In one case I have reviewed, a Florida man remarried, and seven months into the marriage he signed a new will leaving everything to his three adult children and nothing to his wife. He died about three weeks after signing it. His widow asked the probate court for the homestead, a family allowance and her elective share. His son, serving as personal representative, pointed to the prenuptial agreement she had signed, in which each of them gave up any claim to the other’s property. She answered that he had never told her what he owned, and she took that argument all the way to the Florida Supreme Court in 1980, asking it to strike down the statute that excuses disclosure before a marriage. She lost everything she had asked for.

I have a few take-home points.

The first is that her argument would have had real force in a divorce. Florida’s premarital act lets a spouse escape unconscionable terms where there was no fair disclosure, no written waiver of it and no way to know. The probate code asks nothing of the kind for an agreement signed before the wedding, and she was in probate court.

The second is that the court left a door open, and it is the door I would look at first in any case like hers. A signature that was coerced or otherwise improperly obtained, or a person who lacked capacity when signing, can still undo the agreement after a death. Coercion and capacity are questions about the day of signing, and the answers live in the people who were in the room.

Practice pointer. Draft every prenup to survive the stricter divorce test even though the death side requires less. Attach the disclosure schedule and the written waiver of further disclosure, and the agreement holds in both courts.

Avoid treating the absence of a disclosure requirement at death as a reason to skip disclosure. The same document will be read under the divorce statute if the marriage ends that way first.

An honest limit belongs here. Whether particular terms are unconscionable is decided by a judge looking at that agreement and that marriage, and two agreements that look alike can come out differently. Nobody can tell you how a challenge will end without reading the agreement and learning how it was signed.

Kevin D. Klagge, Esq., admitted in Florida since 2012. The case above is a published opinion in other parties’ matter, not a matter this firm handled, and it predicts nothing about yours.

Updated on October 2, 2026. Reviewed by Kevin D. Klagge, Esq., Fla. Bar No. 99502. Attorney Kevin Klagge represents families, businesses, and international clients in estate and tax planning, business structuring, and international law, with a focus on Florida legal tools. He litigates estate and business issues in court. General information about Florida law, not legal advice, and no attorney-client relationship is created. Do not send confidential information until we have agreed to represent you.