Just the actual tax assessed by the other states.
So you usually have to do the non-resident states first.
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Usually???? You need to specify which state is your resident state, and which other states are involved.
Why??? Because some states have reciprocal tax agreements between them and a few others have reverse-reciprocal tax agreements.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*