Colorado Tax Deadlines
State income tax filing deadlines, extensions, and estimates for 2026.
Colorado Department of Revenue
https://tax.colorado.gov
individual deadline
Due: Apr 15, 2026
Extension: Oct 15, 2026
Form: Form DR 0104
Colorado provides an automatic 6-month extension to file.
Estimated Payments
Sole Proprietorship deadline
Due: Apr 15, 2026
Extension: Oct 15, 2026
Form: Form DR 0104
Business income reported on CO personal return.
Estimated Payments
Partnership deadline
Due: Mar 16, 2026
Extension: Sep 15, 2026
Form: State partnership return
Calendar-year due date follows federal timing for pass-through entities.
S Corporation deadline
Due: Mar 16, 2026
Extension: Sep 15, 2026
Form: State S-corporation return
Calendar-year due date follows federal timing for pass-through entities.
C Corporation deadline
Due: Apr 15, 2026
Extension: Oct 15, 2026
Form: State C-corporation return
Calendar-year due date follows federal timing for corporations.
Estimated Payments
LLC deadline
Due: Mar 16, 2026
Extension: Sep 15, 2026
Form: State LLC return
Calendar-year due date follows federal timing for pass-through entities.
Nonprofit deadline
Due: May 15, 2026
Extension: Nov 15, 2026
Form: State nonprofit return
Nonprofit annual return generally due the 15th day of the 5th month.
Estimated Tax Payments
View all quarterly estimated payment due dates for Colorado.
FAQ
Does Colorado conform to federal due dates?
Many Colorado deadlines follow the federal calendar. Always confirm on Colorado Department of Revenue.
Where can I file Colorado tax forms?
Visit Colorado Department of Revenue at https://tax.colorado.gov for official forms and e-file options.