Iowa's top marginal state income tax rate is 3.8%. State tax is progressive here, so most filers pay an effective rate well below the top figure — the calculator applies a blended approximation rather than modeling the full bracket schedule.
Recently consolidated to a flat individual income tax. Statewide median household income is $73,000, which is the default loaded above.
Remember that a state with no income tax is not automatically cheaper overall. Iowa has an effective property tax rate of 1.4% and average homeowners insurance of $1,800 a year — states without wage income tax typically recover revenue through property or sales taxes.