You can claim a refundable Minnesota credit of $120 for each month you served in a combat zone or qualified hazardous duty area. Partial months count as whole months, and you can claim it even if you had no income and owed no tax. A surviving spouse can claim it if the service member died while serving in a qualifying area.
Apply online through the Minnesota Department of Revenue credit for military service application, or file Form M99. You have to file within 3½ years of the original due date of the return for the time you served.
Your orders or Leave and Earnings Statements showing the months served in the qualifying area, and your federal return showing that the combat pay was excluded from gross income.