New York CNN Business  — 

More than a dozen of the richest Americans have a message for 2020 presidential candidates: Tax us more.

In a letter sent to candidates Monday, 18 members of some of the nation’s wealthiest families advocated for a wealth tax on people who amassed great personal fortunes, including themselves.

“We are writing to call on all candidates for president, whether they are Republicans or Democrats, to support a moderate wealth tax on the fortunes of the richest one-tenth of the richest 1% of Americans – on us,” said the letter, which was first published in the New York Times Monday.

It said that millions of middle-class Americans already pay a wealth tax annually on their primary form of wealth: property taxes on their homes. The letter points out that Democratic candidates Elizabeth Warren, Beto O’Rourke and Pete Buttigieg have proposed a wealth tax. But the letter’s writers said, “Some ideas are too important for America to be part of only a few candidates’ platforms.”

This letter is not the first time that wealthy Americans have called for more taxes on themselves and others who are well-off. Berkshire Hathaway (BRKA) CEO Warren Buffett famously said he believed it was wrong that his income was taxed at a lower rate than that of his secretary. That prompted President Barack Obama to propose a minimum tax on millionaires’ incomes that became known as the “Buffett rule.” But that and other tax-the-rich proposals have typically been limited to taxes on income or inheritances, not on overall wealth.

Among those signing the letter are financier George Soros, a major donor to liberal causes, and his son Alexander. Another signer is Abigail Disney, a documentary filmmaker and granddaughter of Roy Disney, Walt Disney’s brother. She has been critical of CEO pay levels, including that of Disney CEO Robert Iger.

Also signing the letter are Facebook (FB) co-founder Chris Hughes, who is the co-chair of the Economic Security Project, which advocates for a guaranteed income for all Americans. Molly Munger, the daughter of Berkshire vice chairman Charlie Munger, also signed the letter. She started the Advancement Project, a public policy group dedicated to the “fair distribution of opportunities and privileges.”

Others signing the letter include Louise and Robert Bowditch, Sean Eldridge, Stephen English, Agnes and Catherine Gund, Nick Hanauer, Arnold Hiatt, Regan Pritzker, Justin Rosenstein, Stephen Silberstein, Ian Simmons and Liesel Pritzker Simmons. The final name on the letter is “anonymous.”

The letter said the wealth of the top 1/10th of 1% is nearly equal to the wealth of the lowest 90% of American households.

“Those of us signing this letter enjoy uncommon fortunes, but each of us wants to live in an America that solves the biggest challenges of our common future,” it said. The letter said the trillions in tax revenue raised through such a wealth tax should be spent on addressing climate change, universal child care, student loan debt relief, infrastructure modernization, public health and tax credits for those with low incomes.