The Microsoft founder and billionaire spoke about the Democratic presidential candidate’s plan at The New York Times DealBook conference on Wednesday.
“I’ve paid over $10bn [£7.8bn] in taxes. I’ve paid more than anyone in taxes,” he said. ”If I had to pay $20bn, it’s fine.
“But when you say I should pay $100bn, then I’m starting to do a little math about what I have left over.”
He added: “Sorry, I’m just kidding.”
Ms Warren has proposed a 6 per cent tax on wealth above $1bn.
Asked if he would speak to Ms Warren about her tax plans, he said: “You know I’m not sure how open minded minded she is.
“Or that she’d even be willing to sit down with somebody who has large amounts of money.”
Mr Gates also said he would not make “political declarations” about who he would vote for if the choice was between Donald Trump and Ms Warren.
“But I do think no matter what policy somebody has in mind, a professional approach is even – as much as I disagree with some of the policy things that are out there, I do think a professional approach to the office – whoever I decide would have the more professional approach in the current situation probably will weigh, is the thing that I will weigh the most.
“I hope the more professional candidate is an electable candidate.”
I’m always happy to meet with people, even if we have different views. @BillGates, 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.) https://t.co/m6G20hDNaV
— Elizabeth Warren (@ewarren)
Ms Warren responded on Twitter, saying she would be happy to meet with Mr Gates to “explain exactly how much you’d pay under my wealth tax”.
She added: “I promise it’s not $100bn.”
Mr Gates is worth an estimated $107bn, according to Bloomberg.
Last week, Ms Warren revealed how she would fund her controversial Medicare for All plan, insisting ordinary Americans would not pay “one penny” extra in taxes.