BASIC INFORMATION
WHO (must file):
Residents:
All residents who filed a federal return
must file a Colorado
income tax return.
Nonresidents:
You must file if you have Colorado source
income and are required to file a federal
return,
or have a Colorado income tax liability.
WHAT (forms do you file)
Residents:
Form 104 Colorado Individual Income Tax
Return
Nonresidents:
Form 104PN Part-year/Nonresident Colorado
Individual Income Tax Return
WHEN (are the tax returns due)
Original due date: April 15th
Extended due date: October 15th
WHERE (do you mail the tax returns)
Colorado
Department of Revenue
1375 Sherman Street
Denver, CO 80261-0005
