Note that you only need to calculate this deduction if you itemized your deductions for the state on your 2015 return and included your federal income taxes. To check this, take a look at your 2015 Montana return line 42, if the standard deduction box is checked, then you can stop here. If the itemized deduction is checked, next look at the attached worksheet for state itemized deductions and assure that you deducted your 2015 estimated federal income taxes paid during the year. If so move on to calculating if any or a portion of your refund is taxable using the second worksheet above.
