© John Lamparski / Getty Images Bill Gates questions Elizabeth Warren's "wealth tax" plan.



Senator Elizabeth Warren said she would "love to explain" to Bill Gates how much he'd pay under her proposed wealth tax after the world's second wealthiest person said he believed he might pay $100 billion under the levy.

Gates, who added he was "just kidding" after making the remark, is just one of several billionaires who have spoken out against Warren's wealth tax, which would add a 6% surcharge on fortunes above $1 billion to raise money for her Medicare-for-all plan.

Gates is one of several billionaires who have publicly questioned Warren's plan. On Tuesday, JP Morgan Chase's Jamie Dimon — worth an estimated $1.6 billion — told CNBC that the Democratic presidential candidate "vilifies successful people." Billionaire investor Leon Cooperman, meanwhile, was reduced to tears while discussing the 2020 election on CNBC, saying he believes Warren is calling billionaires "deadbeats."

The debate over taxation and fairness comes amid rising wealth inequality. While the U.S. tax system is supposed to be progressive, meaning that wealthier households pay a larger share of their income in taxes than the middle class and the poor, America's 400 richest families now pay a lower tax rate than people in the middle class, according to recent research from two prominent economists, Emmanuel Saez and Gabriel Zucman of the University of California at Berkeley.

Speaking at the New York Times' Dealbook conference on Wednesday, Gates expressed concern about Warren's proposed tax, although he added that he's in support of progressive taxation.

"I've paid over $10 billion in taxes. I've paid more than anyone in taxes," Gates said. "But when you say I should pay $100 billion, then I'm starting to do a little math over what I have left over."

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Gates also said he wasn't sure if Warren would meet with him. "I don't know how open-minded she is or if she'd even be willing to sit down with somebody who has large amounts of money," he said.

Warren shot back on Twitter, saying she'd be happy to sit down with him.

"I'm always happy to meet with people, even if we have different views," she wrote, tagging Gates in her tweet. "If we get the chance, I'd love to explain exactly how much you'd pay under my wealth tax. (I promise it's not $100 billion.)"

Not only is Gates the wealthiest of the country's billionaire crowd to weigh in on Warren's wealth tax, but also one of the most philanthropic. He and his wife, Melinda Gates, co-created the Giving Pledge with fellow billionaire Warren Buffett, which is a vow to give away the bulk of their personal fortunes to charity during their lifetimes.