I myself never have to deal with state taxes. But having done my time overseas while in the military, I still retained my "home state" for tax purposes. Fuzzy recollections from those days, I seem to recall that for some of those that had home states that taxed personal income, your income was excluded from state taxation if two conditions were met.
1) You earned the money while physically working for that money outside of that state.
2) You were not physically in that state for more than "X" number of days during the tax year.
