Had Kevin Costner and Christine Baumgartner divorced in Palm Beach County instead of Santa Barbara, their 2004 prenuptial agreement would very likely have held up just as it did in California, and her challenge to its spousal support waiver would have faced even steeper odds. Florida does not require independent counsel to waive alimony, and it enforces prevailing-party fee clauses. The child support fight, the move-out deadline, and the timeline would all have looked different, though.

The Costner case is a useful study for South Florida families with a prenup, a premarital home and children. It shows what a well-drafted prenup can and cannot control. This post walks through the major issues and explains how Florida law would treat each one. It is commentary on publicly reported events, not a view on either party’s conduct.

Baumgartner filed for divorce in Santa Barbara County Superior Court in May 2023, after 18 years of marriage, and the case was finalized in February 2024. Nearly every dispute traced back to the couple’s premarital agreement.

Date	Event
Feb 2024	Court records filed February 20 show the divorce is final (AP via WNDU)
Sept 2023	The couple announce an amicable settlement of all issues, ending a planned November trial on the prenup’s validity (NBC News)
Sept 2023	After two days of testimony, Judge Thomas Anderle sets child support at $63,209 a month (Fox 35)
Aug 2023	Baumgartner asks the court to raise child support to $175,057 a month (TODAY)
July 2023	Temporary child support set at $129,755 a month; Costner ordered to advance $200,000 in attorney’s fees and $100,000 in forensic costs (Fox 7)
July 2023	Judge orders Baumgartner to move out of the Santa Barbara-area estate by July 31 (NBC News)
June 2023	Costner files to enforce the prenup’s 30-day move-out clause; he says the home is a premarital asset bought in 1988 (NBC News)
May 2023	Baumgartner files for divorce citing irreconcilable differences; she initially seeks about $248,000 a month in child support (Fox News)
Sept 2004	The couple marry at Costner’s Aspen, Colorado ranch after signing a premarital agreement

Under the prenup, Costner reportedly owed Baumgartner $1 million after she filed, a $200,000 deposit toward a new home, and a year of property taxes and insurance. She, in turn, had 30 days to leave his separate-property residence. Costner had offered about $75,000 a month in child support before the court ruled. The couple had three children, all teenagers when the case was filed.

In Florida, Baumgartner’s challenge to the prenup would likely have been harder to win than in California. Florida’s version of the Uniform Premarital Agreement Act, Section 61.079, Florida Statutes, lets spouses waive or limit alimony and decide in advance who keeps which property.

Under Section 61.079(7), a Florida court will refuse to enforce a premarital agreement only if the challenging spouse proves one of the following:

• Involuntary signing. The agreement was not signed voluntarily.
• Fraud, duress, coercion, or overreaching. The agreement was the product of improper pressure or deception.
• Unconscionability plus nondisclosure. The agreement was unconscionable when signed, and the spouse did not receive fair and reasonable disclosure of the other’s finances, did not waive disclosure in writing, and did not otherwise know about them.

Three differences from California stand out:

Issue	California	Florida
Independent counsel for a spousal support waiver	Required, or the waiver is unenforceable (Cal. Fam. Code § 1612(c))	Not required by statute
Unconscionability of a support waiver	Judged at the time of enforcement	Judged at signing; a narrow exception applies if the waiver would leave a spouse on public assistance (§ 61.079(7)(b))
Waiting period before signing	Seven days for unrepresented parties (Cal. Fam. Code § 1615)	None by statute, though a last-minute signing can support a duress claim

The Costner agreement was signed 16 years before Baumgartner filed. A Florida judge would look at fairness and disclosure as of 2004, not at how wealthy Costner had become by 2023. Florida does not void a prenup simply because it later looks lopsided.

The agreement’s built-in penalty also matters. Baumgartner was reportedly warned that losing a challenge would mean repaying more than $1 million plus Costner’s legal fees (LBC). The Florida Supreme Court held in Lashkajani v. Lashkajani, 911 So. 2d 1154 (Fla. 2005), that prevailing-party attorney’s fee clauses in prenups are enforceable. A Florida prenup can raise the cost of an unsuccessful challenge in much the same way. For more, see our guide to prenuptial agreements in Florida and our high-net-worth prenup FAQ.

A Florida court would almost certainly treat Costner’s home, bought in 1988, as his nonmarital property. Under Section 61.075, assets acquired before the marriage belong to the spouse who brought them in.

The value added during the marriage is a separate question. In Florida, enhancement in value of a nonmarital asset is marital when it results from either spouse’s work or from marital money. Paying down a mortgage on a premarital home with marital income can also create a marital share. Our Marital Mortgage Paydown Calculator estimates that share. A prenup like Costner’s, which reportedly kept his residence separate, would close those doors.

The move-out fight would also play out differently:

• Temporary exclusive use. A Palm Beach County judge can grant one spouse temporary exclusive use of a residence through a temporary relief order, often with the children’s stability in mind.
• The prenup still counts. A clear move-out clause would weigh heavily, and a judge would likely set a firm deadline, much as Judge Anderle did with his July 31 order.
• Domestic violence overrides. A protective injunction can award exclusive use of a home regardless of title or a prenup. Nothing like that was alleged in the Costner case.

In Florida, as in California, a prenup cannot cap child support. Section 61.079(4)(b) says a premarital agreement may not adversely affect a child’s right to support. The $30,000-a-month child support figure that NBC News reported was in the Costner prenup would not bind a Palm Beach County judge.

Florida’s guidelines in Section 61.30 work differently from California’s formula. The schedule stops at $10,000 of combined monthly net income. Above that, the basic obligation is the $10,000 amount plus a percentage of the excess:

Number of children	Percentage of combined net income above $10,000 a month
1	5.0%
2	7.5%
3	9.5%

Time-sharing then reshapes the number. When each parent has at least 20% of the overnights, Section 61.30(11)(b) multiplies the basic obligation by 1.5 and credits each parent for their overnights. With three children, a 50/50 schedule and nearly all the income on one side, the paying parent’s share works out to roughly three-quarters of the basic obligation.

As a purely hypothetical illustration, take $1 million a month in combined net income, almost all earned by one parent. The basic obligation would be about 9.5% of $990,000 plus the schedule amount, or roughly $97,000. Under equal time-sharing, support would land near $73,000 a month before any deviation. That is in the same range as the $63,209 the California court ordered. Try our Florida Child Support Calculator for a starting estimate.

The real fight in high-income Florida cases is over deviation. A judge may move up to 5% from the guideline amount after considering the children’s needs and the family’s standard of living, and further with written findings. In Finley v. Scott, 707 So. 2d 1112 (Fla. 1998), the Florida Supreme Court confirmed the guidelines apply to high earners, while leaving room to deviate based on the children’s actual needs. The lifestyle argument Baumgartner’s lawyers made in Santa Barbara is the same argument a Florida parent would make. See our page on child support in a Florida divorce.

Both Costner and Baumgartner asked for joint custody, and Florida law would have pointed them the same way. Since 2023, Section 61.13(2)(c)1 presumes that equal time-sharing is in a child’s best interests. A parent seeking more must prove otherwise by a preponderance of the evidence.

Three Florida rules would shape a case like this one:

• A written parenting plan. Florida does not use the word “custody.” The court approves a parenting plan that sets the schedule and assigns shared parental responsibility for major decisions.
• Teenagers’ preferences. Under Section 61.13(3)(i), a child’s reasonable preference is one factor, weighed by the child’s maturity. Florida judges usually hear it through a guardian ad litem or an evaluator, not courtroom testimony.
• Relocation limits. Moving a child more than 50 miles from the principal residence for at least 60 consecutive days requires the other parent’s written agreement or court approval under Section 61.13001. A parent leaving a premarital home, as Baumgartner did, would need to stay within that range or get permission.

Overnights also drive child support. Our Florida Overnight Timesharing Calculator counts them under a proposed schedule.

Baumgartner reportedly planned to challenge the prenup’s spousal support waiver. In Florida, that waiver would likely be enforced at final judgment, because Section 61.079 expressly allows spouses to eliminate alimony by agreement. The narrow exception is a waiver that would leave a spouse eligible for public assistance, which was not a realistic concern here.

Florida does draw one line Californians may not expect. Since Belcher v. Belcher, 271 So. 2d 7 (Fla. 1972), Florida courts have held that a prenup cannot waive temporary support while the divorce is pending. A spouse who signed away alimony can still ask for temporary support until the final judgment.

Without a prenup, the 2023 rewrite of Section 61.08 would govern. Florida measures a marriage from the wedding to the filing date, so a September 2004 wedding and a May 2023 filing makes an 18-year, mid-length marriage.

Alimony type	Florida rule	For an 18-year marriage
Temporary	Only while the case is pending	Available, even with a prenup waiver
Bridge-the-gap	Up to 2 years; not modifiable	Available
Rehabilitative	Up to 5 years; requires a specific plan	Available
Durational	Up to 60% of the marriage’s length for a 10–20 year marriage; capped at 35% of the net-income gap	Up to about 11 years
Permanent	Eliminated in 2023	Not available

Even without a waiver, Florida’s 35% cap and the need-and-ability test mean alimony is rarely the largest number in a high-income case. Our Florida Durational Alimony Calculator shows the limits for a given marriage.

The Santa Barbara court ordered Costner to advance $200,000 in attorney’s fees and $100,000 for forensic accountants. A Palm Beach County judge has the same power under Section 61.16, which awards fees based on one spouse’s need and the other’s ability to pay. Under Rosen v. Rosen, 696 So. 2d 697 (Fla. 1997), a Florida judge may also weigh whether a party litigated unreasonably. Our page on the expense of litigation in a Florida divorce explains how these awards work.

The calendar would also differ:

• No six-month wait. California requires six months between service and a final judgment. Florida’s Section 61.19 requires only 20 days after filing. A September settlement in Florida could have become final within weeks, not in February.
• Front-loaded disclosure. Under Family Law Rule 12.285, both spouses exchange financial affidavits and core documents early. That narrows fights over income like the ones that drove the Costner support hearings. See our post on discovery in a Florida divorce.
• Mediation first. The Fifteenth Judicial Circuit generally requires family mediation before trial, which is where most Palm Beach County cases settle, often confidentially.

Our Florida divorce roadmap shows each stage from filing to final judgment.

The Costner case shows that a solid prenup decides most of the money questions, while the children’s issues stay with the court. Families in West Palm Beach, Palm Beach, Jupiter, Wellington, Palm Beach Gardens, and Boca Raton can take these steps:

• Disclose fully and sign early. Complete financial disclosure and time to review are the best defense against a Section 61.079 challenge.
• Each spouse with a lawyer. Florida does not require it, but independent counsel makes a duress or overreaching claim much harder to prove.
• Address the home. Spell out who stays in a premarital residence, for how long, and who pays to move.
• Do not try to set child support. A prenup cannot limit it. Plan instead for how a high-income parent will document the children’s actual needs.
• Use fee-shifting clauses. Under Lashkajani, a prevailing-party fee provision can discourage a weak challenge.
• Revisit the agreement. A postnuptial agreement can update terms after children, a business, or a large increase in wealth.

If you are negotiating a prenuptial agreement or facing a divorce in which one already exists, contact the Law Offices of James S. Cunha, P.A. at (561) 429-3924 to schedule a confidential consultation. Our office at 250 S. Australian Avenue, Suite 1402, West Palm Beach, is minutes from the Palm Beach County Main Courthouse, and we represent clients throughout Palm Beach, Martin, St. Lucie, Broward and Miami-Dade counties.

This article discusses publicly reported events and general principles of Florida law for informational purposes only. It does not express an opinion on the conduct of either party, is not legal advice, and does not create an attorney-client relationship. Laws change, and every case depends on its facts.