The presidential primaries are still months away, but Sen. Elizabeth Warren has already doubled her wealth tax.

As part of her plan to pay for "Medicare for All," Warren would double the top rate of her wealth tax to 6% from 3%.

That would mean Jeff Bezos would pay more than $6.5 billion in wealth taxes this year alone. Not to mention the other new taxes Warren plans for the rich, which includes taxing capital gains at the same marginal tax rate as ordinary income, which means that if Bezos sells Amazon stock – as he does every year to fund Blue Origin – he would pay a tax rate of 37% on the stock. Previously, the rate was 23.8%.

But there is another less-publicized feature of Warren's health-care tax that could be even larger. In addition to taxing capital gains as ordinary income, she would also tax unrealized capital gains. That means that Bill Gates, whose fortune has increase $18 billion this year from Microsoft stock appreciation, would pay a wealth tax of more than $6 billion, plus another $6 billion on the appreciation of his stock – even if he didn't sell any shares. So Gates would owe over $12 billion in taxes this year – unless he put more into his foundation first.

We will see whether Warren's new numbers will change Gates' support for a wealth tax.