Is President Trump’s historic Palm Beach estate, Mar-a-Lago, worth $18 million or closer to $500 million? That question — and Mr. Trump’s property valuations more broadly — is central to the $250 million civil fraud case brought by New York’s attorney general, Letitia James, against the former president.

For the right answer, the advice of Florida real estate brokers and appraisers seems to be that the judge is way off the mark.

On Tuesday, a New York Supreme Court judge, Arthur Engoron, used a Palm Beach County assessor’s appraisal of Mar-a-Lago at $18 million as evidence to rule in a pre-trial judgment that Mr. Trump, his sons, and co-defendants in the Trump Organization committed fraud by inflating the values of their real estate holdings to gain more favorable terms on loans and insurance.

If Judge Engoron’s ruling stands, Mr. Trump could lose control of his New York properties. The stakes are high. The rest of the counts against Mr. Trump in the civil fraud case will be tried starting Monday, after an appeals court denied Mr. Trump’s bid to delay it this week.

Mar-a-Lago, a members’ only club where Mr. Trump also lives, is likely out of reach of New York regulators, but the accusation that Trump overstated its value is central to Judge Engoron’s fraud ruling. So is Mar-a-Lago worth only $18 million? That valuation is certainly raising eyebrows in real estate circles and on social media for being “insanely low.”

Palm Beach is one of the wealthiest towns in the world and the value of a historic, waterfront property there such as Mar-a-Lago can be astronomical. “I spoke with my appraisers,” a Palm Beach real estate broker, Lee Allen Schultz, tells the Sun, “they thought the $18 million was ridiculous.”

“Just the land value alone, I think we get close to the $500 million, with just that alone, without even the property and how iconic it is — iconic before Trump even took it over,” Mr. Schultz says.

“It’s almost obnoxiously low,” another Palm Beach realtor with over 30 years of experience in the area, tells the Sun. Like many brokers the Sun contacted, he did not want his name used because of the controversy surrounding the former president and the fact that 50 percent of his customers might be turned off “just seeing my name in print next to his.”

This broker would not give an estimate for the property but noted that Mar-a-Lago has 17 acres and stretches across the island, with beachfront on both sides. “There are no comparables. There’s nothing to go on. It would be like you asking me how much is the Mona Lisa worth?” he says.

“The value of Mar-a-Lago would vary depending on whether it’s assessed as a private club or a residential property in Palm Beach,” a real estate broker, Victoria Piroso, tells the Sun. “If it were put on the market, it would likely be viewed as an income-generating asset. In such a scenario, it could potentially fetch around $500 million or even more, given its historical significance on the island.”

These brokers pointed to other properties on Palm Beach Island that have sold recently for sums that far exceed $18 million and contain only a small fraction of Mar-a-Lago’s acreage or square footage. Mr. Schultz points to 940 North Lake Way, a bayfront property with less than one acre, that sold in July for $50 million. Rush Limbaugh’s widow sold his Palm Beach estate in March for $155 million.

Mr. Trump bought Mar-a-Lago in 1985 for $10 million, but Palm Beach property prices have gone up substantially in recent years. Forbes magazine appraised Mar-a-Lago at $160 million in 2018. The  property boasts 128 rooms, a 20,000-square-foot ballroom, tennis courts, and a waterfront pool.

Mar-a-Lago is deed restricted and cannot be converted to a residential property, which may lower its value. The brokers who spoke with the Sun, though, say the appraised value between $18 and $27.6 million is laughable. They also note that Mar-a-Lago’s property tax assessed value is $33 million, which is also “very low,” though property owners generally like this to be low to save money on taxes. 

A chief property tax appraiser for Palm Beach County, Cecil Jackson, told Newsweek that clubs like Mar-a-Lago are assessed based on membership numbers, dues, and the cost to run the facility. These valuations are “for tax purposes only and not for financing or … for a lending institution,” he said.

President Trump took to Truth Social after Tuesday’s ruling to call Judge Engoron’s ruling a “radical attack” and a “Witch Hunt.”

“This partisan Democrat judge pretends Mar-a-Lago is only worth $17 million. Mar-a-Lago is worth over $1 billion. A tennis court at Mar-a-Lago is worth $17 million,” Mr. Trump posted.  “This is a factual dispute for a jury to decide at trial. Not by a judge — without a trial.”

“In an attempt to destroy my father and kick him out of New York, a Judge just ruled that Mar-a-Lago, in Palm Beach Florida, is only worth approximate ‘$18 Million dollars,’” Eric Trump posted to X. He added that the property is “speculated to be worth” more than “a billion dollars making it arguably the most valuable residential property in the country. It is all so corrupt and coordinated.”

Donald Trump Jr. joked on X, “If Mar-a-Lago is worth $18 million… I’ll take 10 please!”

The $18 million assessment may be laughable, but the ramifications are serious. Judge Engoron wrote in his decision that Mr. Trump’s $426 to $612 million valuation of Mar-a-Lago to secure loans was “an overvaluation of at least 2,300 percent.”

“A discrepancy of this order of magnitude, by a real estate developer sizing up his own living space of decades, can only be considered fraud,” Judge Engoron wrote. “The documents here clearly contain fraudulent valuations that defendants used in business, satisfying OAG’s burden to establish liability as a matter of law against defendants.”