Elon Musk on Saturday asked his 62.5 million followers on Twitter if he should sell 10% of his Tesla stock.

“Much is made lately of unrealized gains being a means of tax avoidance, so I propose selling 10% of my Tesla stock,” Musk wrote in a tweet referring to a “billionaires’ tax” proposed by Democrats in the US Senate.

Musk tweeted that he would abide by the results of the poll. It received more than 700,000 responses in the hour after Musk posted it, with nearly 56% of respondents approving the proposal to sell the shares.

Musk’s shareholding in Tesla comes to about 170.5 million shares as of 30 June and selling 10% of his stock would amount close to $21bn based on Friday’s closing, according to Reuters calculations.

Analysts say he may have to offload a significant number of shares anyway to pay taxes since a large number of options will expire next year.

The comments from Musk come after the proposal in Congress to tax billionaires’ assets to help pay for Joe Biden’s social and climate-change agenda. Musk is one of the world’s richest people and owner of companies including SpaceX and Neuralink. He has criticized the billionaires’ tax on Twitter.

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

Tesla board members including Elon Musk’s brother Kimbal have recently sold shares in the electric carmaker. Kimbal Musk sold 88,500 shares while fellow board member Ira Ehrenpreis sold shares worth more than $200m.