I understand your comment but your response would drive a smaller addition to the state return, not more. In my case say I have $511 of muni-bond interest in a national/multi-state fund. In practice the Iowa amount is not consequential at 0.2% but let's say for argument it is 5% like FL. Then I would exempt 5% of the $511 or ~ $25 and 511-25 = $486 would be added back on my Iowa return (rather than the original $511).
I have checked the multiple states source without any additional selections. IN MY CASE, the Fed return is properly picking up the $511, the MN resident state return is picking up the $511 and the Iowa is for some reason adding another $2 and entering $513. I verified this by zeroing out the interest and $2 still appears in the Iowa addition.
