The DR 1106 Annual Transmittal of State 1099s should be filed in January for withholding taxes reported on Federal form 1099.
If you are filing an amended return you are required to mark the amended return box. 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.
Any 1099 statements you distribute that contain Colorado state withholding must be sent to the department. Attach this form to the total withholding statements (1099s) that were furnished to each payee.