Colorado State Tax Returns: Rates, TABOR Refund, and Deadlines

Your Colorado state tax return is filed on Form DR 0104, due April 15 of the year after the tax year ends, with a flat 4.0% rate applied to your federal taxable income after Colorado-specific additions and subtractions. The 2025 return is due April 15, 2026, and the same 4.0% rate carries into 2026. Even filers who owe nothing should file, because Colorado’s TABOR sales tax refund is claimed on the return itself.

Who Has to File

Colorado requires a return from anyone who had a federal filing obligation (or any Colorado tax liability) and falls into one of three groups:

Full-year residents, who owe Colorado tax on all income regardless of where it was earned.
Part-year residents, who owe tax on everything earned while living in Colorado plus any Colorado-sourced income from the rest of the year.
Nonresidents with Colorado-sourced income, such as wages from a Colorado employer or income from Colorado rental property.¹

Nonresidents specifically need to file whenever they have taxable Colorado-sourced income and a federal filing obligation.² Keep records of your residency dates and the sources of your income, because those details decide which portion of your income Colorado can tax.

The April 15 Deadline and the Extension Trap

Returns are due April 15 of the year following the tax year, moving to the next business day if the 15th falls on a weekend or holiday.³

Colorado grants an automatic six-month extension to file, with no separate request required.⁴ The catch: the extension covers paperwork only, not payment. Anything you owe is still due April 15. If you think you will owe, send an estimated payment with Form DR 0158-I or through Revenue Online by April 15, or penalties and interest start running from that date.

The 4.0% Flat Rate

Colorado taxes every dollar of taxable income at the same rate. HB24-1065 cut the individual and corporate rate from 4.40% to 4.0% for tax years beginning on or after January 1, 2025, and that 4.0% rate applies to both the 2025 and 2026 returns.⁵ Multiply your Colorado taxable income by 0.04 to get your base liability before credits.

Building the Return on Form DR 0104

The DR 0104 starts with your federal taxable income — the bottom-line figure from Form 1040, after the standard or itemized deduction has already been subtracted. Colorado then layers its own additions and subtractions on top. Your federal return has to be finished first.

Have these ready:

Your completed federal Form 1040 or 1040-SR for the taxable income figure.
W-2s and 1099s showing Colorado tax withheld.
Social Security Numbers or ITINs for everyone on the return.
Your residency dates if you moved into or out of Colorado during the year.

Form DR 0104 and its schedules are on the Department of Revenue website or can be completed through Revenue Online.⁶ Part-year residents and nonresidents also need Form DR 0104PN to calculate the Colorado-taxable portion of their income.

Revenue Online is the state’s free e-file portal and processes faster than paper.⁷ Approved third-party software also connects to the state system. If you mail a paper return, the address depends on whether you are including a payment; checks go with a DR 0104V voucher, payable to the Colorado Department of Revenue. Use certified mail if you want proof of a timely postmark.

The TABOR Sales Tax Refund

The Taxpayer’s Bill of Rights, a 1992 constitutional amendment, caps state revenue and requires any surplus to be refunded.⁸ For the 2025 tax year, the main refund mechanism is the state sales tax refund credit, claimed directly on the DR 0104. The amount is a flat dollar figure that varies by filing status and adjusted gross income tier, ranging from $19 for a single filer at the lowest AGI tier up to $118 for joint filers at the top tier.

You can receive the credit as a payment even if you owe no Colorado tax, but you have to file a return to get it, and the claim deadline is the October 15 extended filing date.⁹ In some surplus years Colorado has used a temporary rate reduction instead (the 2024 year used a temporary 4.25% rate), but for 2025 the sales tax credit is the vehicle.⁸

Credits and Subtractions Worth Checking

Child Tax Credit and Family Affordability Tax Credit

Colorado’s state child tax credit covers children under age 6 and runs from $200 to $1,200 per qualifying child depending on income. It phases out above $77,000 AGI for single filers and $87,000 for joint filers.¹⁰

The separate family affordability tax credit covers children under 17 and is substantially larger: up to $3,273 per child age 5 and under, and up to $2,455 per child ages 6 through 16, at the lowest income levels. It phases out completely at $85,000 AGI for single filers and $96,000 for joint filers. Both credits are claimed on Schedule DR 0104CN.¹⁰

Colorado Earned Income Tax Credit

If you claimed the federal EITC, Colorado automatically allows a state EITC equal to 50% of the federal amount for 2025.¹¹ It is refundable, so you receive it as a payment even with no tax liability.

Pension and Annuity Subtraction

Taxpayers age 55 to 64 can subtract up to $20,000 of qualifying pension and annuity income from Colorado taxable income. At 65 or older, the limit is $24,000.¹² Joint filers calculate the subtraction separately for each spouse based on that spouse’s own age and income; unused room cannot shift between spouses.

Property Tax, Rent, and Heat Credit Rebate

The PTC Rebate is aimed at older residents with limited income. You must be a full-year Colorado resident, age 65 or older (or a surviving spouse age 58 or older), with total income under $19,094 (single) or $25,788 (joint). The maximum rebate is $1,178. Beginning January 1, 2026, individuals with disabilities under age 65 and surviving spouses under 58 will claim benefits through the new Disability Assistance Credit instead; you can claim only one of the two programs per tax year.¹³

Deduction Addback for High Earners

If your federal AGI exceeds $300,000, Colorado requires you to add back part of the deduction you claimed on your federal return, whether standard or itemized. The addback is the amount by which your federal deduction exceeds a statutory cap.¹⁴

The cap drops sharply between 2025 and 2026:

Tax years 2023 through 2025: $12,000 (single), $16,000 (joint).
Tax year 2026 and later: $1,000 (single), $2,000 (joint).

A single high-earner taking the federal standard deduction in 2025 adds back only what exceeds $12,000. In 2026, that same filer adds back everything above $1,000, which pushes Colorado taxable income up by thousands of dollars.¹⁴ It is worth planning for before the 2026 return.

Quarterly Estimated Payments

If you have income without withholding — self-employment earnings, rent, investment gains — Colorado generally requires quarterly estimated payments when you expect to owe more than $1,000 in net tax after withholding and credits.¹⁵ The deadlines are April 15, June 15, September 15, and January 15 of the following year, each shifting to the next business day if it lands on a weekend or holiday.¹⁶ Use the DR 0104EP worksheet to size each payment; underpayment is calculated on Form DR 0204.

Late Filing, Late Payment, and Payment Plans

Colorado’s late payment penalty is 5% of the unpaid tax for the first month or fraction of a month, plus 0.5% for each additional month the balance remains unpaid, capped at 12%. Interest also accrues from the original due date. These apply even if you filed an extension, because the extension does not postpone payment. Paying what you can by April 15 and filing later is almost always cheaper than filing on time and paying late.

If you cannot pay in full, Colorado offers monthly payment plans with no extra setup fee beyond the ongoing penalty and interest. After you receive a bill, you can arrange a plan through Revenue Online. For current-year debt before a bill arrives, call the Collections Section at (303) 205-8291 after April 15. If standard terms create hardship, Form DR 6596 (Statement of Economic Hardship) requests extended terms; keep paying the standard amount while that application is reviewed. Missing a payment, filing a later return late, or failing to return the required waiver cancels the plan and makes the full balance due immediately.¹⁷

Fixing a Return You Already Filed

To correct an error, file Form DR 0104X through Revenue Online or by mail with the revised figures.¹⁸ One deadline catches people out: if the IRS changes your federal return, you must file a Colorado amended return within 30 days of receiving notice of the federal change.¹⁹ Because the Colorado calculation begins with federal taxable income, a federal adjustment almost always changes your state liability as well.

Rules for Military Servicemembers

Active-duty servicemembers keep the residency of the state they lived in when they entered service unless they formally change it. If Colorado is your home of record, your military pay is included in Colorado taxable income. If you are stationed in Colorado but a legal resident elsewhere, Colorado cannot tax your military pay, though any non-military Colorado-sourced income still has to be reported.²⁰

A servicemember whose home of record was Colorado but who later changed legal residence can reacquire Colorado residency through steps like registering to vote, buying residential property, or titling a vehicle here. After reacquiring residency, active-duty military pay can be subtracted from Colorado taxable income on Schedule DR 0104AD. Full-year Colorado residents stationed outside the United States for at least 305 days during the tax year may file as nonresidents, and an accompanying spouse meeting the same test can do the same. Personnel serving in a designated combat zone can postpone both filing and payment for 180 days after the assignment ends, with penalties and interest deferred during that period.²⁰

1
Department of Revenue – Taxation. Individual Income Tax – Filing Requirements
2
Department of Revenue – Taxation. Part-Year and Nonresident
3
Department of Revenue – Taxation. Individual Income Tax – Due Dates and Filing Extension
4
Department of Revenue – Taxation. Extension Payment for Colorado Individual Income Tax
5
Colorado General Assembly. HB24-1065 – Reduction of State Income Tax Rate
6
Department of Revenue – Taxation. DR 0104 – Individual Income Tax Return
7
Department of Revenue – Taxation. Department of Revenue – Taxation
8
Department of Revenue – Taxation. Taxpayer’s Bill of Rights (TABOR) Information
9
Department of Revenue – Taxation. Income Tax Topics: State Sales Tax Refund
10
Colorado Department of Revenue. 2025 Colorado Child Tax Credit Instructions
11
Department of Revenue – Taxation. Income Tax Topics: Earned Income Tax Credit
12
Department of Revenue – Taxation. Income Tax Topics: Social Security, Pensions and Annuities
13
Department of Revenue – Taxation. Property Tax/Rent/Heat Credit (PTC) Rebate
14
Department of Revenue – Taxation. Individual Income Tax Guide
15
Department of Revenue – Taxation. DR 0104EP – Individual Estimated Income Tax Payment Form
16
Department of Revenue – Taxation. Individual Income Tax – Estimated Payments
17
Department of Revenue – Taxation. Payment Plans
18
Department of Revenue – Taxation. DR 0104X – Amended Individual Income Tax Return
19
Department of Revenue – Taxation. Amending an Individual Income Tax Return
20
Department of Revenue – Taxation. Active Duty Servicemembers