If you discover that your tax return was incorrect, you have five years from the due date of the original return to file an amended Montana tax return and to correct any mistake on your previous return. When you file this amended return, you will need to complete a new Montana tax return that reflects the corrections that you are making to your previously filed tax return. Important: Include copies of any schedules submitted with the original filing even if none of the amounts previously reported have changed. If you are amending your return to carry back a net operating loss, please check the "NOL" box found in the upper left hand corner of your Form 2. Montana Form AMD is available to help you reconcile the changes to the original return. This form is for your information and records. Although not required, we suggest that you complete and attach Form AMD, or a similar form outlining the changes, to your corrected tax return. You can download Form AMD from our website at revenue.mt.gov under "Downloadable Forms".