if you own apartments in 3 states, are you required to pay income taxes in all 3 states as well?

Working and earning income in each state and yes each state would like to have a share of the state income taxes on that income during the tax filing season for that past tax year.

Hope that you find the above enclosed information useful. 09/20/2014

As bob points out (sort of), income is source by where you (or if a landlord, where the property was) made the money AND by where you live.

You would have to determine for each state whether you are a resident, non-resident or part year resident. Then fill out the tax forms accordingly. If you pay taxes to state A, you may get a partial credit in state B.

California is particularly aggressive in claiming you as a resident.

yes, each state requires taxes on income sourced in that state

as a non resident it is possible none of it will be taxed but if you rent the entire year, there very likely will be some taxable income

This assumes that you do not rent out any of the apartments.

You always have to declare one state as your residence. So you will have to pay taxes there.

There are seven states with no income tax and two that tax interest income only.

Well if you are renting it out to others then yes you are. It gets filed along with your schedule e information about rent income. To get more info I would look into schedule e instructions from the irs site because that will guide you.