Postnuptial Agreements and Asset Protection in Florida

A postnuptial agreement is a contract between spouses executed after marriage that defines property rights, allocates debts, and establishes spousal support terms in the event of divorce or death. For married couples who did not execute a prenuptial agreement before the wedding, a postnuptial agreement is the only contractual tool available to override Florida’s default equitable distribution rules while the marriage continues.

From an asset protection standpoint, postnuptial agreements address a gap that statutory exemptions cannot fill. Tenancy by the entirety protects jointly owned assets from individual creditors during the marriage, but that protection terminates the moment a divorce is finalized. Homestead protects the residence from forced sale by judgment creditors, but the family court retains broad discretion over the marital home in a dissolution proceeding. A postnuptial agreement establishes enforceable rules that the family court must follow when dividing property, provided the agreement satisfies Florida’s enforceability requirements.

The Casto Standard: How Postnuptial Agreements Differ from Prenuptial Agreements

Florida’s Uniform Premarital Agreement Act, codified at § 61.079, governs prenuptial agreements executed on or after October 1, 2007. By its terms, the statute applies only to premarital agreements and proceedings under the Florida Family Law Rules of Procedure. Postnuptial agreements fall outside the UPAA’s scope and are instead governed by Florida common law, with the enforceability framework established by the Florida Supreme Court in Casto v. Casto, 508 So. 2d 330 (Fla. 1987).

The distinction matters because the Casto standard imposes requirements that are different from, and in some respects stricter than, those of the UPAA. Under the UPAA, a prenuptial agreement is enforceable even if its terms are unfair, provided the challenging party received adequate financial disclosure or voluntarily waived the right to disclosure. Under Casto, a postnuptial agreement can be vacated on the additional ground that it makes an unfair or unreasonable provision for the challenging spouse, given the parties’ relative circumstances at the time of execution.

Casto establishes two independent grounds for challenging a postnuptial agreement. The first is that the agreement was obtained through fraud, deceit, duress, coercion, misrepresentation, or overreaching. The second is a two-part test: the challenging spouse must first establish that the agreement is unfair or unreasonable given the parties’ relative ages, health, education, and financial status, and if unfairness is established, a rebuttable presumption arises that the agreement resulted from concealment by the other spouse or from the challenging spouse’s lack of adequate knowledge of the marital finances.

The practical consequence is that postnuptial agreements face greater judicial scrutiny than prenuptial agreements. A prenuptial agreement between parties with vastly unequal bargaining power will generally be enforced if disclosure was adequate. A postnuptial agreement with the same terms may be vacated if the court finds the outcome unreasonable, even if both parties had full knowledge of the finances. Courts recognize that spouses negotiating during a marriage are not dealing at arm’s length and apply heightened scrutiny accordingly.

What a Postnuptial Agreement Can Address

Postnuptial agreements in Florida can address the same financial matters as prenuptial agreements. The agreement can define which assets are separate property and which are marital property subject to division. It can establish, modify, waive, or eliminate spousal support. It can allocate responsibility for debts incurred before and during the marriage. It can also address the disposition of property at death, including provisions that coordinate with wills, trusts, and life insurance designations.

A postnuptial agreement cannot adversely affect a child’s right to support. Florida courts determine child custody and child support based on the child’s best interests at the time of separation, and no marital agreement can override that authority.

One important use of a postnuptial agreement is reclassifying assets acquired during the marriage. Under Florida’s default rules, most assets acquired by either spouse during the marriage are marital property subject to equitable distribution under § 61.075. A postnuptial agreement can designate specific assets as the separate property of the acquiring spouse, including a business started during the marriage, an investment account funded with one spouse’s earnings, or real estate purchased in one spouse’s name. Without this contractual designation, those assets would be divided by the court in a divorce.

Enforceability Requirements

Florida courts require postnuptial agreements to satisfy several conditions to be enforceable.

The agreement must be in writing and signed by both spouses. Oral agreements regarding property division are not enforceable in dissolution proceedings.

Both spouses must enter into the agreement voluntarily. Because spouses owe fiduciary duties to each other, courts examine the circumstances surrounding execution more carefully than they would for a prenuptial agreement negotiated before the marriage. Agreements presented during a period of marital crisis, particularly when one spouse threatens divorce unless the other signs, face particular scrutiny for coercion.

Full and fair financial disclosure is essential. Each spouse must provide the other with a complete picture of their income, assets, and liabilities. The Casto court emphasized that when a postnuptial agreement is unreasonable on its face, a presumption arises that the challenging spouse lacked adequate knowledge of the marital finances. Attaching current financial statements, tax returns, and account summaries as exhibits to the agreement is the most effective way to defeat this presumption.

Independent legal counsel for each spouse, while not strictly required, substantially strengthens enforceability. The Casto court noted that competency of counsel is not itself a ground to vacate a postnuptial agreement, but the absence of independent counsel for both parties invites arguments that one spouse did not understand the agreement’s consequences.

The agreement must not be unconscionable. Unlike the UPAA framework for prenuptial agreements, where unconscionability alone is insufficient without a concurrent disclosure failure, the Casto standard allows courts to vacate a postnuptial agreement based on unreasonableness combined with inadequate knowledge, even if the disclosure was technically provided. The question is whether the challenging spouse actually understood the financial information, not merely whether it was made available.

Postnuptial Agreements vs. Prenuptial Agreements

The table below summarizes the key differences between postnuptial and prenuptial agreements under Florida law.

Factor	Prenuptial Agreement	Postnuptial Agreement
Governing law	§ 61.079 (UPAA)	Common law; Casto v. Casto
When executed	Before marriage	During marriage
Consideration	Marriage itself	Independent consideration may strengthen enforceability
Unfairness standard	Enforceable even if unfair, provided disclosure was adequate	May be vacated if unfair and challenging spouse lacked adequate knowledge
Fiduciary scrutiny	Parties not yet in fiduciary relationship	Spouses owe fiduciary duties; heightened judicial scrutiny
Disclosure requirement	Fair and reasonable disclosure required unless waived in writing	Full disclosure essential; inadequate knowledge triggers presumption against enforceability
Counsel requirement	Not required but recommended	Not required but strongly recommended given fiduciary relationship

The heightened scrutiny applied to postnuptial agreements means that drafting precision and documentation quality are more important than for prenuptial agreements. A postnuptial agreement that would survive challenge as a prenuptial agreement may fail under the Casto standard if the court determines the outcome is unreasonable in light of the parties’ relative circumstances.

When a Postnuptial Agreement Makes Sense for Asset Protection

Several common scenarios create a need for postnuptial asset protection that a prenuptial agreement was not available to address.

A spouse who starts a business during the marriage faces the risk that the business will be classified as marital property and subject to equitable distribution. Without a postnuptial agreement, the non-owner spouse may be entitled to a share of the business’s value, potentially forcing a buyout, valuation dispute, or liquidation. A postnuptial agreement can designate the business as the owner-spouse’s separate property and waive the non-owner spouse’s claim to its value.

A spouse who receives a substantial inheritance during the marriage should keep those funds segregated from marital assets to preserve their separate character. Commingling inherited funds with joint accounts converts them into marital property. A postnuptial agreement can confirm that specific inherited assets remain separate property even if some commingling has occurred, though the agreement’s effectiveness depends on meeting the Casto enforceability standards.

A couple experiencing increased liability exposure—such as a spouse entering a high-risk profession—may use a postnuptial agreement to concentrate assets in the non-debtor spouse’s name. This strategy carries fraudulent transfer risk if implemented after a claim has arisen or is reasonably anticipated, but a postnuptial agreement executed before any specific liability exists creates a contractual basis for the asset allocation that predates the creditor’s claim.

Couples who marry without a prenuptial agreement and later realize they need defined property boundaries can use a postnuptial agreement to accomplish retrospectively what a prenuptial agreement would have done prospectively. The key difference is that the postnuptial agreement must satisfy the stricter Casto standard rather than the UPAA framework.

Limitations

A postnuptial agreement does not protect assets from all divorce-related obligations. Alimony waivers in postnuptial agreements are enforceable, but a court retains authority to order sufficient support to prevent a spouse from becoming destitute and eligible for public assistance. Child support cannot be waived or modified by agreement.

The Casto standard’s unfairness test creates a practical ceiling on how one-sided a postnuptial agreement can be. An agreement that leaves one spouse with substantially all marital assets while the other receives little or nothing is vulnerable to challenge, even if both spouses had independent counsel and full financial disclosure. The more imbalanced the agreement, the greater the burden on the defending spouse to demonstrate that the challenging spouse entered into it with full knowledge and without coercion.

Postnuptial agreements also do not insulate assets from fraudulent transfer claims. If a married couple executes a postnuptial agreement transferring the debtor spouse’s assets to the non-debtor spouse after a claim has arisen, a creditor can challenge the transfer under Chapter 726 of the Florida Statutes. The postnuptial agreement does not provide a shield against avoidance actions merely because the transfer was made pursuant to a marital contract.