In general, when filing a part-year return, most states will tax:
- all the income you received when you were a resident of that state; plus
- the income that came from sources within that state while you were a nonresident.
Let's say you lived in State A at the beginning of the year. They will tax all the income you had through February plus the wages from your old company, which is located in State A.
State B will tax you on all the income you received from February on.
Prepare the return for State A first. Then any taxes you paid will flow to State B's return for a credit.
