Below are the 10 states with the highest state income tax rates in 2018:California: 1 to 13.3 percentHawaii: 1.4 to 11 percentOregon: 5.0 to 9.9 percentMinnesota: 5.35 to 9.85 percentIowa: 0.33 to 8.53 percentNew Jersey: 1.4 to 10.75 percentVermont: 3.35 to 8.75 percentWashington, D.C.: 4.0 to 8.95 percentNew York: 4.0 to 8.82 percentWisconsin: 4.0 to 7.65 percent