The year 2021 has seen President Biden and congressional Democrats explore, very publicly and painfully, seemingly every possible way to squeeze more tax money out of the American people. This exploration has taken place though the federal government just enjoyed the biggest revenue haul in two decades, inflation is higher than it’s been in three decades, and Senator Kyrsten Sinema (D., Ariz.) has taken all tax-rate increases off the table.

Just over the past week, a billionaire wealth tax proposal has suddenly moved from the edge to the very center of the negotiating table for President Biden’s sweeping Build Back Better agenda.

What explains the shift? The reasons are both negative and positive.

On the negative side: Kyrsten Sinema.

As Democrats inch closer to finalizing their social spending package, Senate Democrats are eyeing a tax on billionaires amid pushback on income and corporate levy hikes.

The proposal, called the Billionaires Income Tax, may affect roughly 700 Americans with more than $1 billion of wealth or earning over $100 million annually for three consecutive years.

Billionaires may face an annual levy on the increased value of assets, such as stocks and bonds, regardless of when they sell, known as “mark-to-market.” However, investors may still write off losses every year.