SPRINGFIELD, Ill. — The Illinois Senate has approved a graduated income-tax structure that charges a rate of 7.99 percent for those that make the most.

The plan authored by Olympia Fields Democratic Sen. Toi Hutchinson was approved 36-22.

It would not take effect until 2021 and only if voters approve a constitutional amendment to replace the flat-rate income tax. The Senate approved asking the voters to decide on an amendment earlier Wednesday.