What to know about Vermont's wealth tax

If signed into law, it would mark the first-ever wealth tax in U.S.

In a yellow-walled conference room at the Vermont statehouse this week, one attendee ate ice cream and another bounced a toddler on her lap -- but all were focused on a bill that would tax personal wealth for the first time in U.S. history.

At the committee meeting, legislators took up a measure that would tax the capital gains of people with more than $10 million in net worth, even if the gains have not been cashed out.

In other words, if a wealthy person's stock or real estate holdings go up in value over a given year, the individual would have to pay taxes on those gains, even if he or she doesn't sell the underlying asset.

The bill, one of an array of similar measures introduced by state-level Democrats nationwide, takes up a cause championed on Capitol Hill by progressives like Democratic Massachusetts Sen. Elizabeth Warren and Independent Vermont Sen. Bernie Sanders.