A political movement that wants to increase taxes for Massachusetts’s highest income earners is picking up steam as it heads toward the ballot.

The group Raise up Massachusetts is pushing an amendment to the state constitution that would add an additional four percent tax on income over $1 million.

It’s not exactly right to call this proposal a “millionaires’ tax”, since the higher rate would only apply to income above one million dollars. So the first cool million you earn in a given year would be taxed the same way it is now, but anything you earn over the million mark is where the new higher tax would come in. While the state has a fair share of folks with over a million in the bank, few millionaires in Massachusetts actually take home seven figures in a given year.

That means that their aren’t even that many top-dollar earners in Massachusetts who this would apply to.

The million-and-up tax hike would hit around one half of one percent of Massachusetts taxpayers, currently estimated to be fewer than 20,000 people. Call it the “Half of the One Percent” tax.

“I was working with hundreds of activists across the state, collecting tens of thousands of signatures and I know from talking to people at polling locations that, on street corners, in my neighborhood and across Massachusetts, that people are ready for investment in education and transportation,”

Ben Wright, the director of Progressive Massachusetts, one of several left-leaning groups that banded together to collect the signatures.

Opponents say the plan will backfire when many of those high-earners move out of the state and take all their taxable income dollars with them. Southern New Hampshire or sunny Florida might start to look pretty good, especially if you’ve already got buckets of money and the mobility that comes with it.

The group dropped off over a hundred and fifty thousand signatures from voters it needs to move the process forward.

It’s a long process to change our tax system and supporters also need lawmakers to approve it before it can appear on voters’ 2018 ballot.