How do state income tax rates vary across the US?

State income tax structures vary widely. Nine states have no individual income tax at all (Florida, Texas, Nevada, Wyoming, South Dakota, Washington, Alaska, Tennessee, and New Hampshire on wages). Others use flat rates (Illinois at 4.95%) or graduated brackets (California tops out at 13.3%). State taxes can add substantially to your effective rate and must be factored into any income or residency planning.