DOR Taxation web site

Electronic Filing Authorization

All tax preparers who are accepted by the IRS to e-file federal returns are automatically accepted to e-file Colorado state returns through the IRS. They must be able to send returns to the Martinsburg Service Center and use tax software that is accepted by Colorado. If you have registered as an Electronic Return Originator (ERO) with the IRS and you have an Electronic Filer Identification Number (EFIN) you are automatically accepted by Colorado. You do not have to fill out a registration form or send Colorado a copy of your Federal acceptance letter.

Colorado Electronic Filing Help Desk: (303) 866-3889



Individual Income Tax Information
Individual Income Software Developer Information Web Page

Electronic Filers Handbook


Corporation Information
Corporation Software Developer Information Web Page

Partnership/S-Corp Information
Partnership/S-Corp Software Developer Information Web Page