California's top marginal state income tax rate is 13.3%. 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.
Proposition 13 caps assessment growth at 2% a year while you own the home. Statewide median household income is $92,000, which is the default loaded above.
Remember that a state with no income tax is not automatically cheaper overall. California has an effective property tax rate of 0.71% and average homeowners insurance of $1,600 a year — states without wage income tax typically recover revenue through property or sales taxes.