Subtractions on the state return are for income items that are taxable on the federal return but not taxable on the state return. Since exempt interest dividends are not taxable on the federal return, there would be no subtraction for the state return.
However, if any of your exempt interest dividends are taxable on the state return you'd see an addition. If any of the exempt interest dividends are from investments in other states, that amount is taxable and will be added to your Minnesota return.
