Postnuptial Agreement in Florida: What It Covers, Cost, and When It Holds Up

Marriages change. One spouse inherits a house from a parent. The other puts family savings into a new business. One of you steps away from work to raise the kids. Suddenly the question “what happens to all this if we ever split up?” is not so easy to ignore.

A postnuptial agreement in Florida lets married couples answer that question now, calmly and on their own terms.

This guide explains what a postnup can and cannot do, how Florida courts decide whether one is valid, and what it takes to get one. If you are ready to put an agreement in writing, our postnuptial agreement lawyers can walk you through it.

What Is a Postnuptial Agreement?

A postnuptial agreement, or postnup, is a written contract that spouses sign after they are married. It sets out how property, debts, and support would be handled if the marriage ends in divorce, and it can also address what each spouse receives if the other dies.

Without an agreement, Florida law decides those questions for you. In a divorce, a judge divides marital property starting from an equal split and decides alimony based on statutory factors. A postnup lets you replace those default rules with terms you both chose while you were getting along.

Couples sign postnups for practical reasons, and many of them are not planning to divorce at all. Common triggers include:

• an inheritance or a large gift that one spouse wants to keep separate;
• starting or growing a business or professional practice;
• one spouse leaving a career to care for children or family;
• a second marriage, where each spouse wants to protect assets for children from a prior relationship; and
• rebuilding trust after a financial secret or infidelity.

What a Postnup Can and Cannot Cover in Florida

A postnup is powerful, but it is not unlimited. Florida courts will enforce agreements about money and property between the spouses. They will not let a contract decide issues that belong to the children.

What You Can Include

• Separate and marital property. Florida law treats assets excluded “by valid written agreement of the parties” as nonmarital, so a postnup can keep a house, an inheritance, or an investment account out of the division.
• Debts. You can decide who is responsible for existing debts and for debts taken on later.
• Alimony. Spouses can agree to set, limit, or waive alimony. Before you give it up, read our guide to alimony in Florida so you know what you would be waiving.
• A business. A postnup can protect a company or practice, including its future growth.
• Rights at death. Spouses can waive inheritance rights such as the elective share and homestead, which is explained below.

Without a clear agreement, these questions often turn into the most expensive part of a divorce. Learn more about how Florida handles property division in a divorce.

What a Florida Court Will Not Enforce

Child support and time-sharing cannot be locked in by a postnup. Florida courts decide those issues based on the child’s best interests at the time of the case, and child support is checked against the state guidelines.

A clause that limits child support or sets a parenting schedule in advance is not binding on the judge.

If you have children, those decisions are made later with help from our child custody attorneys, not in the agreement. Terms that try to control personal behavior, such as household chores, are also generally a poor fit for a legal contract.

Can a Postnup Include an Infidelity Clause?

An infidelity clause gives a spouse who cheats less property or alimony if the marriage ends. Couples often ask for one after an affair. No Florida statute addresses these clauses, and a court may be reluctant to enforce a term that punishes personal conduct.

Florida divorces are no fault, but a judge may still consider adultery and its economic impact when deciding alimony. Have a lawyer write the money terms so the rest of the agreement still works if a judge strikes the cheating clause.

Postnup vs. Prenup in Florida

A prenup and a postnup can cover similar ground, but Florida treats them differently. The biggest difference is which rules apply.

Section 61.079 applies only to agreements made “in contemplation of marriage.” A postnup falls outside it, so Florida courts judge it under the standard the Florida Supreme Court set in Casto v. Casto. If you are not married yet, see our page on prenuptial agreements instead.

Can a Postnup Change an Existing Prenup?

Yes. If you signed a prenup before the wedding, Florida law lets you amend or revoke it after marriage, but only by a written agreement signed by both spouses. No new payment or exchange is needed for the change to be enforceable.

Many couples use a postnup this way to update an old prenup after a business, a move, or children change the picture.

Postnuptial Agreement vs. Divorce Settlement

A postnup is signed by spouses who plan to stay married. It only sets the rules in case the marriage ends later. A marital settlement agreement is different. It is signed to end the marriage and divides property and support now, usually during the divorce case.

The difference matters. In Macar v. Macar (2001), the Florida Supreme Court held that the Casto test does not govern a settlement reached through court-ordered mediation in a contested divorce. An agreement signed after a divorce is filed is generally treated as a settlement, with different rules for challenging it.

When Is a Postnuptial Agreement Enforceable in Florida?

A postnup is generally legally binding in Florida if it is in writing, signed voluntarily by both spouses, and signed with a clear picture of each other’s finances. Under Casto v. Casto, a spouse can ask a court to set it aside on two grounds:

1. Unfair dealing. The agreement was reached through fraud, deceit, duress, coercion, misrepresentation, or overreaching.
2. Unfair terms without enough information. The agreement makes an unfair or unreasonable provision for the challenging spouse, and that spouse did not have enough knowledge of the other’s finances when signing.

That second ground is where most of the risk lives. It means a lopsided agreement can still hold up, but only if the spouse who gave up more knew what they were giving up.

Why Full Financial Disclosure Matters

Once a spouse shows that a postnup is unreasonable for them, given both spouses’ circumstances, Florida courts presume that the other spouse concealed financial information or that the challenging spouse did not know enough about the other spouse’s finances. The spouse defending the agreement must then prove one of two things:

• there was a full, frank disclosure of the value of the property and both spouses’ income before signing; or
• the challenging spouse already had a general and approximate knowledge of the property and income.

In practice, the safest approach is to attach a written financial disclosure to the agreement, listing assets, debts, and income for both spouses. Giving each spouse time to review it, and ideally a separate lawyer, makes a later challenge much harder.

Waiving rights at death has its own formal rule.

Under Section 732.702 of the Florida Statutes, a spouse can waive the elective share, homestead, and other inheritance rights, but the waiver must be signed in front of two witnesses, who also sign it.

When it is signed after the wedding, each spouse must also make a fair disclosure of their estate. A postnup should line up with each spouse’s will and estate plan.

How to Get a Postnuptial Agreement in Florida

You can sign a postnup any time after the wedding, whether that is a month or twenty years later. A careful process usually looks like this:

1. Talk about goals. Agree on what you want the postnup to protect and why.
2. Exchange financial information. Each spouse lists assets, debts, income, and approximate values.
3. Get legal advice. Ideally, each spouse has a separate lawyer who explains what they are giving up.
4. Draft the agreement. One lawyer drafts, and the other reviews and suggests changes.
5. Take time to review. Avoid last-minute signing, which can look like pressure later.
6. Sign properly. Both spouses sign in writing, with two witnesses for any inheritance waiver. Many lawyers also have it notarized.
7. Revisit it after big changes, such as a new business, a move, or the birth of a child.

Can You Use a Template or Skip the Lawyer?

Florida law does not require a lawyer, and online postnuptial agreement templates are easy to find. The risk is that a generic form was not written for Florida.

Templates often miss the two-witness rule for inheritance waivers, skip a proper disclosure schedule, or use rules from community property states such as California.

A postnup is only tested years later, when one spouse has a reason to fight it. A short review by a Florida lawyer costs far less than finding out in court that the agreement does not hold.

If you still choose to do it yourselves, attach a signed financial disclosure for both spouses, give each spouse time to read everything, and sign any inheritance waiver in front of two witnesses. One lawyer usually represents only one spouse, so the other spouse should get an independent review.

How Much Does a Postnuptial Agreement Cost?

The cost of a postnuptial agreement depends mostly on how complex your finances are and how much negotiating is needed. A simple agreement between spouses with a few assets costs far less than one involving a business, real estate, or retirement accounts.

Many family lawyers charge a flat fee for drafting a postnup, while others bill by the hour. If each spouse has a separate lawyer, there will be two fees. The main cost drivers are:

• the number and type of assets involved, especially a business;
• whether the agreement covers alimony and rights at death;
• how much back-and-forth the spouses need; and
• how much work it takes to prepare the financial disclosure.

Before hiring anyone, ask for a written fee quote that says what it includes: drafting, revisions after the other spouse’s lawyer reviews it, the financial disclosure schedules, and the signing with witnesses. A low quote that leaves out review or signing can cost more later.

Compared with a contested divorce, a postnup is usually a small expense. Our guide on how to file for divorce in Florida shows how quickly costs grow when spouses have to fight over property and support.

Talk to Weldon Law Group About a Postnuptial Agreement

A postnup only helps if it holds up when you need it. Weldon Law Group drafts and reviews postnuptial agreements with Florida’s disclosure rules and the Casto standard in mind. Because we also handle estate planning, we can make sure your agreement and your will work together.

Contact Weldon Law Group to talk about protecting your property and your peace of mind.

Frequently Asked Questions