Democratic presidential hopeful Elizabeth Warren offered to meet Bill Gates after the Microsoft billionaire expressed skepticism about her proposal for a “wealth tax” affecting the richest Americans — and assured him he would not have to pay $100 billion.

Gates, speaking at a New York Times conference on Wednesday, said he favored “progressive” taxation but worried about the impact of a large wealth tax on “innovation.”

“I’ve paid over $10 billion in taxes, I’ve paid more than anyone,” Gates, one of the world’s wealthiest individuals, said in the interview.

“If I had to pay $20 billion, it’s fine but when you say I should pay $100 billion, ok, then I’m starting to do a little math … You really want the incentive system to be there.”

Asked if he would consider meeting Warren, Gates said, “I’m not sure how open-minded she is, or that she would even be willing to sit down with somebody who has large amounts of money.”

Warren took the cue from Gates in a response on Twitter, offering to meet the Microsoft founder and philanthropist.

“I’m always happy to meet with people, even if we have different views,” Warren wrote.

Addressing Gates directly, she said “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.)”

On Thursday, Warren’s website was updated with a “tax calculator” enabling billionaires to determine how much they would pay under her proposals.

Gates would pay $6.37 billion from a net worth of $107 billion, according to the calculator, slightly less than the $6.697 billion that would be owed by Amazon co-founder Jeff Bezos.

Warren has proposed a tax on the wealthiest US citizens to help cover her health care program and has also said she wants to break up some of the big technology firms such as Facebook and Google.

Gates said he was “glad to pay a fair bit more in taxes” but said he did not plan to play a role in the election campaign through political donations.

When asked who he’d vote for if Warren were to face off with Donald Trump, Gates — who has openly criticized the Republican president in the past — said he’d opt for the “more professional” candidate.

“I hope that the more professional candidate is an electable candidate,” he said Wednesday at the New York Times event.