This return, together with remittance by check, draft or money order made payable to the Colorado Department of Revenue, must be filed with the:
Colorado Department of Revenue
Denver, CO 80261-0009
on or before the 15th day of the month following the close of the taxable period. Mailed returns must be postmarked the 15th day of the month or prior thereto.
If you are filing an amended return you are required to mark the Amended Return box. A separate amended return must be filed for each period. The amended return must show all tax columns as corrected, not merely the difference(s). The amended return will replace the original return in its entirety.