Musk, the company’s founder and CEO and posted a Twitter poll Saturday afternoon which said, “Much is made lately of unrealized gains being a means of tax avoidance, so I propose selling 10% of my Tesla stock. Do you support this?”

Musk receives no salary from Tesla. His 170.5 million shares of Telsa were worth $208.3 billion as of the close of trading on Friday. At the price of $1,2209.09 per share, 10 percent of them would be valued at $20.8 billion. With a long-term capital gains tax rate of 20% for someone in Musk’s income bracket, it would equal a tax bill from the sale approaching $4.2 billion.

He has owned 80% of those 170.5 million Tesla shares since the company’s initial public offering in 2010.

A ProPublica investigation in June found Musk paid no federal income taxes in 2018 — and in 2017 he paid only $65,000.

“Note, I do not take a cash salary or bonus from anywhere. I only have stock, thus the only way for me to pay taxes personally is to sell stock,” Musk tweeted on Saturday.

Earlier in the week, Musk offered to sell Tesla stock ‘right now’ if the United Nations could prove $6 billion would solve world hunger.

His comments Monday came after UN World Food Programme (WFP) director David Beasley challenged the ultra-wealthy, and in particular the world’s two richest men — Amazon founder Jeff Bezos and Musk — to “step up now, on a one-time basis” to help solve world hunger in an interview with CNN last week.

“Six billion dollars to help 42 million people that are literally going to die if we don’t reach them. It’s not complicated,” Beasley said on CNN’s Connect the World program with Becky Anderson. The sum would equate to roughly 2% of Musk’s net wealth.

Prince William has also criticized billionaires who are focused on space tourism, which could include Musk, who also founded SpaceX. The company sent the first all-tourist crew to space in September, though most of the company’s revenue comes from commercial launches and NASA contracts.

As of Saturday, Musk is the richest man on earth with a total net worth of $338 billion, according to the Bloomberg Billionaires Index.

CNN’s Chris Isidore and Walé Azeez contributed to this story.