People cast their ballots at a community center during early voting October 25, 2018 in Potomac, Maryland, two weeks ahead of the key US midterm polls. (

Before you get out and vote in Tuesday's midterm elections, better brush up on the ballot measures. Many states have tax issues up for a vote.

A "notable" number of tax measures are on the ballot this year, and if passed, they could have large fiscal effects, said Vanessa Williamson, a fellow in governance studies at Brookings Institution.

During the last 15 years, voters have approved about half of tax measures on ballots, and that's a likely outcome this year. Williamson said she expects voter turnout to be higher this year, compared with the average midterm election, which could influence which measures pass.

"I think it's important more generally to think about what it means for states to turn to their voters to raise taxes, which is normally seen as unpopular," she said.

Issues like marijuana taxes and progressive taxation (for example, Colorado's bill to go from a flat income tax to a graduated one) are more dependent on that higher voter turnout, since they are more partisan issues, Williamson said. Soda and tobacco taxes tend to be less divisive, and so, easier to pass.

Here are some of the big tax issues that voters will decide Tuesday, according to the Tax Policy Center, a joint venture of the Urban Institute and Brookings.