Montana's top marginal state income tax rate is 5.9%. 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.
No general sales tax. Statewide median household income is $69,000, which is the default loaded above.
Remember that a state with no income tax is not automatically cheaper overall. Montana has an effective property tax rate of 0.74% and average homeowners insurance of $2,000 a year — states without wage income tax typically recover revenue through property or sales taxes.