Connecticut's top marginal state income tax rate is 6.99%. 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.
High mill rates make property tax a large share of the monthly payment. Statewide median household income is $91,000, which is the default loaded above.
Remember that a state with no income tax is not automatically cheaper overall. Connecticut has an effective property tax rate of 1.79% and average homeowners insurance of $1,700 a year — states without wage income tax typically recover revenue through property or sales taxes.