2025 Colorado Income Tax Filing Deadlines for 2024 Returns

Colorado State Income Taxes for the 2024 tax year can be prepared and e-filed, along with your IRS or Federal Income Tax Return. You can also find out how to prepare and e-file just an Colorado state return. Check the deadlines for IRS or Federal Tax Returns.

Tax Deadlines and the Colorado Tax Day

The majority of deadlines listed here are for the 2024 tax year and are due in 2025; some apply to upcoming years and some are IRS or federal deadlines. After Oct. 15 you can no longer e-file tax returns or current year tax amendments. They will have to be filed via paper tax forms.

Deadline

Type

Description

Prepare, eFile, Download
CO + IRS Tax Return

Detailed eFile.com Service Overview

Start Federal and Colorado Tax Returns

April 15, 2025

Income Tax Return

Original Deadline to prepare and e-File a Colorado Income Tax Return. You have until October 15 to complete and e-File your Federal Income and Colorado State Income Tax Return. eFileIT

April 15, 2025

Income Tax Extension

Automatic Colorado Income Tax Extension Details

October 15, 2025

Income Tax Return after the automatic April 15 Colorado Tax Extension

Last day to eFile a 2024 Colorado State Income Tax Return for Tax Extension Filers and late eFilers. You can only eFile (to file by paper see below) Colorado Income Tax Return together with an IRS Tax Return. eFileIT

October 15, 2025 via mail-in Forms. Forms incl. Mailing Address

Income Tax Return after the automatic April 15 Colorado Tax Extension

Deadline for taxpayers who got an automatic CO Tax Extension to file their Colorado Income Tax Return by mail-in Forms - the Forms incl. mailing addresses are listed here - is October 15. (Optionally: the eFileIT deadline is Oct. 15). Instructions on how to only - without the IRS return - prepare and file a Colorado State Income Tax Return on eFile.com.

Complete and Mail In Now

Tax Amendment for All Tax Years

Detailed Instructions on how to prepare and mail in a Colorado State Income Tax Return Amendment.

IRS Due Dates

IRS Tax Return, Extension, Amendment Deadlines

Detailed current and future Federal or IRS Income Tax Deadlines

April 15, 2026

2022 Colorado Income Tax Return Refund

The last day to file and claim your 2022 Colorado Income Tax Return. This deadline does not apply if you owe Income Taxes. After that date your 2022 tax refund will expire. Seedetails on unclaimed refunds.

April 15, 2027

2023 Colorado Income Tax Return Refund

The last day to file and claim your 2023 Colorado Income Tax Return. This deadline does not apply if you owe Income Taxes. After that date your 2023 tax refund will expire. Seedetails on unclaimed refunds.

April 15, 2028

2024 Colorado Income Tax Return Refund

The last day to file and claim your 2024 Colorado Income Tax Return. This deadline does not apply if you owe Income Taxes. After that date your 2024 tax refund will expire. Seedetails on unclaimed refunds.

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