2025 Colorado State Tax Deadlines

Colorado Individual Income Tax Filing deadlines and extensions for 2025 for tax professionals to reference when working with clients.

If your client is a resident of Colorado or has been involved in significant business operations within the state, they might be required to file Colorado State Taxes. This document outlines the most important tax deadlines and tax extensions for Colorado in 2025.

2025 Colorado State Tax Deadlines

If your clients are residents or have been involved in significant business operations within Colorado, then they might be required to file Colorado State Taxes. This page outlines the most important tax deadlines and tax extensions for Colorado in 2025.

Colorado Business Tax Deadlines for 2025

C Corporation

Colorado C Corporation Tax Deadlines for 2025
You must file and pay Corporate Income Taxes in Colorado by April 15, 2026.

• File Online with the Colorado Department of Revenue
• File by Mail must be postmarked by the due date
• Form 112 – Colorado Corporation Income Tax Return

Extension to File Taxes in Colorado for 2025 

The Extension Deadline for Colorado corporate tax returns is October 15, 2026.

Colorado automatically grants a six-month extension on filing corporate income tax returns. This means you do not need to file for an extension in Colorado.

This is an extension to FILE, not an extension to PAY – payment is still due April 15, 2026.

Pass-Throughs

Colorado S Corporation & Partnership Tax Deadlines for 2025
You must file in Colorado by April 15, 2026.

• File Online with the Colorado Department of Revenue
• File by Mail must be postmarked by the due date
• Forms:
  • Form 112S – S Corporation Income Tax Return
  • Form 106 – Partnership Return of Income

Extension to File S Corporation & Partnership Taxes in Colorado for 2025
The Extension Deadline for Colorado S Corporation or Partnership tax returns is October 15, 2026.

Colorado automatically grants a six-month extension on filing pass-through entity tax returns. This means you do not need to file for an extension in Colorado.

This is an extension to FILE, not an extension to PAY – payment is still due April 15, 2026.

Colorado Individual Tax Deadlines for 2025

Estimated Tax Deadline for Colorado 2025
Estimated tax payments are due:

• April 15, 2025
• June 16, 2025
• September 15, 2025
• January 15, 2026

Individual Tax Deadline for Colorado 2025
You must file and pay Individual Income Taxes in Colorado by April 15, 2026.

• File Online with the Colorado Department of Revenue
• File by Mail must be postmarked by the due date
• Form 104 – Colorado Individual Income Tax Return

Extension to File Taxes in Colorado for 2025
The Extension Deadline for Colorado individual tax returns is October 15, 2026.

Colorado automatically grants a six-month extension on filing personal income taxes. This means you do not need to file for an extension in Colorado.

This is an extension to FILE, not an extension to PAY – payment is still due April 15, 2026.

Sources

• Colorado Department of Revenue Tax Filing Information
• Colorado Department of Revenue Tax Forms

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The material discussed on this page is meant for general illustration and/or informational purposes only and is not to be construed as investment, tax, or legal advice. You must exercise your own independent professional judgment, recognizing that advice should not be based on unreasonable factual or legal assumptions or unreasonably rely upon representations of the client or others. Further, any advice you provide in connection with tax return preparation must comply in full with the requirements of IRS Circular 230.