Paper: Letter (8.5in x 11in)
COLORADO DEPARTMENT OF REVENUE
DENVER CO 80261-0009
Due on the last day of March when filing online.
Payable to "Colorado Department of Revenue"
on the 28th of February the following calendar year.
To transmit forms W-2 and/or 1099 to the state.
Colorado Department of Revenue
Tax Information Call Center: (303) 238-7378