Can I deduct carryover passive losses (K-1 partnership in a different state) from 2020 Iowa sourced passive income? I'm a nonresident of all states involved.

[SamS1]

Possibly.  In Iowa, you enter all your Federal income, the state tax is calculated, then the Iowa tax is apportion and you are given a tax credit for your out of state income.  This is completed on IA 126.  The numerator is your Iowa source income and the denominator is your total income.   That percentage is subtracted from 100% then multiplied by the total Iowa tax to determine the amount of the Non-resident/Part-year resident tax credit.

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