Tax-Rates.org provides free access to printable PDF versions of the most popular Colorado tax forms. Be sure to verify that the form you are downloading is for the correct year. Keep in mind that some states will not update their tax forms for 2016 until January 2017.
If the form you are looking for is not listed here, you will be able to find it on the Colorado 's tax forms page (see the citations at the bottom of this page).
11/-0001Form 104EP - Estimated Individual Income Tax Return
You must pay estimated income tax if you are self employed or do not pay sufficient tax withholding. Estimated tax payments are due on a quarterly basis; The due dates are: April 15 (first calender quarter), June 15 (second calender quarter), September 15
11/-0001Form 104 - Individual Income Tax Return
Form 104 is the general, and simplest, income tax return for individual residents of Colorado. You may file by mail with paper forms or efile online.