Tax season is officially open in Colorado. The Colorado Department of Revenue, Taxation Division, recently announced that taxpayers can now file their 2023 state income tax returns. They've shared practical tips to help Coloradans avoid delays, reduce filing mistakes, and receive refunds faster.

Whether you're a full-time resident, part-year filer, or someone who earned income in Colorado last year, this guide will walk you through everything you need to know. From who must file and what forms to use, to deductions, credits, and the filing methods available—we’ll break down the process clearly, one step at a time.

Colorado has a flat income tax rate and closely ties state filing requirements to your federal return, so starting early and getting organized is key. We’ll also show you how to file your taxes online for free, claim helpful tax credits, and avoid common errors that might hold up your return.

Do You Need to File a Colorado Tax Return?

If you filed a federal income tax return for 2023, chances are you’ll also need to file one with the state of Colorado. Unlike some states that set minimum income thresholds, Colorado’s requirement is tied directly to your federal filing obligation or whether you earned taxable income from within the state.

Who Must File in Colorado

You must file a Colorado tax return if you meet any of the following conditions:

  • You were a full-year Colorado resident and are required to file a federal return with the IRS
  • You were a part-year Colorado resident and earned income during the time you lived in the state
  • You were a nonresident who earned income from Colorado sources (for example, if you temporarily worked in Denver but live elsewhere)

Colorado also requires you to file even if you don’t owe anything, as long as you had a federal filing requirement. This is especially important for people with lower incomes, retirees, or those who are eligible for a refund based on tax credits.

Examples of Who Should File

  • A college student who worked a part-time job in Colorado and filed a federal return
  • A retiree receiving out-of-state pension income while living in Colorado
  • A freelancer based in another state who earned income from clients in Colorado
  • A family that moved to Colorado in mid-2023 and had income in both states

Don’t Assume You're Exempt

Even if you don’t think you owe state taxes, you may still qualify for a rebate or refund. For example, full-year residents over 18 can receive a sales tax refund—but only if they file. Filing also helps the state determine eligibility for certain income tax credits and ensures accurate records for future years.

Key Colorado Tax Deadlines and What They Mean

Colorado follows the same basic tax calendar as the IRS, and meeting these deadlines is essential—even if you’re not ready to pay immediately. Missing important dates can lead to penalties, delayed refunds, and unnecessary stress.

April 15, 2024: Main Deadline

Your 2023 Colorado tax return and any payment you owe are due by April 15, 2024. This deadline applies whether you file electronically or by mail. The state accepts e-filed returns until midnight, while paper returns must be postmarked no later than that day.

Automatic Filing Extension Until October 15

Colorado grants a six-month automatic extension to file—but it’s essential to know that this extension does not apply to payments. If you owe taxes, you must still estimate and pay at least 90% of your tax liability by April 15 to avoid interest and penalties.

To make an extension payment, use Form DR 0158-I or pay directly through Revenue Online.

Penalties for Missing the Deadline

If you fail to file on time, Colorado may charge:

  • A failure-to-file penalty, which is typically higher than failure-to-pay penalties
  • Daily interest on any unpaid tax starting April 16
  • Additional late payment fees will be imposed if no payment is made by the deadline

Even if you can’t pay immediately, it’s better to file your tax return on time and arrange a payment plan later.

Tip: Don’t Wait to File if You’re Expecting a Refund

If you’re due a refund, there's no penalty for filing late—but there’s also no reason to wait. Filing early may help you avoid identity verification issues or delays in processing.

Which Colorado Tax Forms Do You Need

Filing your Colorado tax return starts with the proper forms. Colorado offers several versions depending on your income type, residency status, and whether you're claiming credits or deductions. Choosing the correct form ensures your return is processed correctly and helps avoid unnecessary delays.

Primary Forms for Most Filers

  • DR 0104: This is the standard Colorado Individual Income Tax Return used by most residents, part-year residents, and nonresidents.
  • DR 0104EZ: A simplified version for full-year residents with basic tax situations. You may qualify to use this if:
    • You have no dependents
    • You take the standard deduction
    • You don’t claim most credits or subtractions
  • DR 0104X: Use this form to file an amended return if you made a mistake or need to correct information on a previously filed return.

Supporting Schedules You May Need

Depending on your situation, you may also need to attach one or more of the following:

  • DR 0104PN: For part-year residents and nonresidents, used to allocate income earned in Colorado.
  • DR 0104AD: To claim subtractions from income such as retirement benefits, military pay, or contributions to CollegeInvest or ABLE accounts.
  • DR 0104CR: Used to claim income tax credits, including the earned income tax credit, child tax credit, and clean energy-related credits.
  • DR 0104US: If you purchased taxable goods from out-of-state vendors and owe consumer use tax.

Payment and Extension Forms

  • DR 0900: If you owe taxes and are mailing a paper check, include this payment voucher.
  • DR 0158-I: If you need to make an extension payment, use this form before April 15.

Where to Find These Forms

All forms and instructions are available for download from the Colorado Department of Revenue’s website at tax.colorado.gov. You can also file electronically through Revenue Online or compatible tax software.

Step-by-Step Guide to Filing Your Colorado Return

Filing your Colorado income tax return doesn’t have to be overwhelming. This step-by-step guide is designed to walk you through the process, whether you’re handling your taxes, using software, or working with a tax preparer.

Step 1: Complete Your Federal Return First

Start by filing your federal tax return (Form 1040). Colorado uses your adjusted gross income (AGI) from the federal return as the starting point for your state filing. Without a completed federal return, you won’t be able to move forward.

Step 2: Gather All Your Tax Information

Have the following documents ready before starting:

  • W-2s and 1099s from all income sources
  • Records of estimated tax payments
  • Statements for deductions or credits (retirement contributions, tuition, etc.)
  • Last year’s state tax return (optional but helpful)

Step 3: Fill Out Colorado Form DR 0104

This is the main form. You’ll enter:

  • Personal information: Name, address, SSN, filing status (must match your federal return)
  • Federal AGI: Transfer from your federal Form 1040
  • Colorado additions and subtractions: Use Form DR 0104AD if applicable
  • Tax owed: Apply the flat 4.4% tax rate to your taxable income
  • Credits: Use Form DR 0104CR to claim any tax credits
  • Payments made: Include withholdings or estimated payments already submitted

Step 4: Include Supporting Schedules if Needed

You may need:

  • DR 0104PN: If you were a part-year resident or earned income in another state
  • DR 0104US: If you owe consumer use tax
  • DR 0104CH: If you’re making a voluntary contribution to a specific fund
  • DR 0104CN or DR 0347: For child tax credit or childcare-related credits

Step 5: Double-Check for Common Errors

Before submitting:

  • Make sure all Social Security numbers are correct
  • Review all math and ensure your refund or amount due is accurate
  • Verify bank account information for direct deposit
  • Check that your filing status is consistent with your federal return
  • Don’t forget to sign and date your return

Step 6: Choose How You Want to File

You can file your taxes online through:

  • Revenue Online at colorado.gov/revenueonline
  • Tax software (e.g., TurboTax, TaxSlayer)
  • A CPA or tax expert

Or, file by mail if you prefer paper returns.

Income Tax Credits and Subtractions You Might Qualify For

Filing your Colorado tax return isn’t just about reporting income—it’s also a chance to reduce your debt or boost your refund by claiming credits and deductions. Colorado offers a range of income tax credits, subtractions, and rebates to help eligible individuals and families maximize their tax savings.

Common Income Tax Credits

Several income tax credit programs can reduce the amount you owe—or increase your refund—if you meet specific income requirements or situations.

  • Earned Income Tax Credit (EITC): Designed for working individuals and families with lower incomes, this credit can provide a significant benefit. Colorado offers a refundable EITC based on your federal eligibility.
  • Child Tax Credit: If you have qualifying children under a certain age, you can claim the child tax credit, which can vary based on income level and number of dependents.
  • Child Care Expenses Credit: Helps offset the cost of child care for working parents.
  • Innovative Motor Vehicle Credit: For those who purchased a qualifying electric vehicle.

You’ll typically need to file Form DR 0104CR to claim these credits.

Subtractions and Deductions That Reduce Your Taxable Income

Colorado allows several deductions (referred to as "subtractions" on state forms) that can lower your income tax burden:

  • Military retirement pay or public pension income
  • Social Security benefits and certain disability payments
  • CollegeInvest 529 contributions (up to $31,000 for joint filers per beneficiary)
  • ABLE account contributions, designed for individuals with disabilities
  • U.S. government interest (such as from savings bonds)

Use Form DR 0104AD to report these subtractions.

Property and Sales Tax Rebates

Full-year Colorado residents age 18 and older may be eligible for the state sales tax rebate—a benefit that requires filing a return even if no tax is owed. The rebate is $800 for individuals and $1,600 for joint filers, provided you meet the residency and income criteria.

Property tax and rent-related rebates are also available through the Property Tax/Rent/Heat Credit (PTC) Rebate program. This is especially useful for seniors, people with disabilities, and low-income households.

When to Get Expert Help

Consulting with a tax expert or using Colorado’s Revenue Online system can help if you're unsure whether you qualify for a particular credit or deduction. They can guide you through the documentation needed and ensure you claim everything you’re entitled to.

How to File Your Taxes Online or By Mail

Once you’ve gathered your documents and completed your return, it’s time to choose how you’ll submit it. Colorado supports both online filing and traditional mail-in methods, and each comes with its pros and cons depending on your access to technology, location, and personal preferences.

Filing Your Taxes Online

The Colorado Department of Revenue recommends e-filing to speed up processing and reduce errors. You can file for free using:

  • Revenue Online at colorado.gov/revenueonline
  • Approved third-party tax software (many offer free versions for simple returns)
  • A tax preparer or CPA

Filing your taxes online offers several benefits:

  • Faster refunds (usually within 3 to 5 weeks)
  • Fewer errors, thanks to automated calculations
  • Immediate confirmation of receipt
  • Accessible from any device with internet access

For those who need assistance, the state offers guidance through its website, and many nonprofit programs in Denver and other areas provide free tax help for qualifying individuals.

Filing by Mail

You can still file your tax return on paper if you prefer. Download the forms from the Colorado Department website, complete them by hand, and mail them to the correct address based on your payment situation.

Mailing Tips:

  • Include all required forms and schedules
  • Sign and date your return
  • Do not staple your check to the return if you owe a balance
  • Use certified mail or delivery tracking
  • Make a copy of your return for your records

Need Help?

You can visit Revenue Online or call the Department of Revenue directly if you encounter issues. Filing doesn’t have to be a hassle—many filers can complete the process in under an hour, especially using digital tools and step-by-step guides.

How to Make Payments or Get Your Refund

Whether you owe money or expect a refund, Colorado offers multiple options to keep the process smooth. Understanding how payments and refunds work can help avoid delays, penalties, or unnecessary paperwork.

If You Owe Taxes

If your return shows that you owe money, you have a few options for paying:

Online Payments

Paying online through Revenue Online is the fastest and most secure option. You can:

  • Transfer directly from a bank account (no fees)
  • Use a credit or debit card (processing fees apply)
  • Schedule payments in advance

Online payments are tracked immediately, helping you avoid late penalties and interest.

Mailing a Payment

If you prefer to mail a check or money order:

  • Make it payable to “Colorado Department of Revenue.”
  • Include Form DR 0900 if filing electronically
  • Write your Social Security number, tax year, and "Form 104" on the check
  • Do not staple the check to your return

To avoid penalties, make sure your payment is postmarked by April 15. Even if you’ve already filed, a payment is considered late if it isn’t submitted by the deadline.

If You’re Expecting a Refund

You'll receive a refund if you’ve paid more than you owe. You can choose:

  • Direct deposit to your bank account (fastest method)
  • Paper check, mailed to your address on file

To track your refund, go to tax.colorado.gov/refund and enter:

  • Your SSN
  • Refund amount or Letter ID
  • Your filing status

Equal Treatment for All Taxpayers

Colorado processes payments and refunds equally, regardless of how you file. Whether you use a CPA, file by mail, or submit through your phone, your return will be handled in the same queue.

Colorado Tax Filing Checklist

Before you submit your Colorado return, take a few minutes to review this checklist. It’ll help ensure your filing is complete, accurate, and ready to go—online or by mail.

Pre-Filing Preparation

  • Prepare all required documents: W-2s, 1099s, and other income forms
  • Review your federal return to confirm adjusted gross income
  • Gather documentation for any deductions, credits, or subtractions
  • Have your banking info ready if you want a direct refund

Completing Your Return

  • Fill out Form DR 0104 or DR 0104EZ, based on your tax situation
  • Attach required schedules like DR 0104AD (subtractions) or DR 0104CR (credits)
  • Include any additional forms, such as DR 0104PN for part-year filers
  • Use your federal return as a reference for key entries

Double-Check Before You File Your Tax Return 

  • Verify names, Social Security numbers, and filing status
  • Ensure your spouse has signed if you file jointly
  • Check your calculations carefully to avoid delays
  • Confirm all required lines are filled, even with a $0 balance
  • Make copies for your records (keep them for several years)
  • Use this example to stay organized: sort forms by type, paperclip schedules, and include a payment voucher if owed 

Final Tips to Maximize Your Refund

  • Review eligibility for the earned income tax credit, child tax credit, and rebate programs
  • Double-check any property tax or rent-related credits
  • File early to maximize your chances of a fast refund
  • If in doubt, consult a tax expert or CPA

Frequently Asked Questions (FAQs)

Who qualifies for the Earned Income Tax Credit in Colorado?

The earned income tax credit is available to individuals and families with low to moderate incomes. To qualify, a person must have earned income from employment or self-employment and meet income limits based on household size. A tax expert can help determine eligibility, especially for part-year residents or those with multiple income sources.

Can I claim the Child Tax Credit if I lived in Colorado for only a year?

Many part-year residents can still claim the child tax credit if they meet IRS guidelines and earned qualifying income. Even if you lived in Colorado for only half the year, you may be eligible if your dependents meet age and relationship requirements. A tax expert can confirm your eligibility based on federal and state rules.

How can I get the maximum refund when filing a Colorado tax return?

To get the maximum refund, claim all eligible credits and deductions, including child care costs, property tax rebates, and education expenses. Submitting receipts for groceries, school supplies, and charitable donations may help if they meet deduction guidelines. Filing early and consulting with tax experts also improves accuracy and helps reduce refund delays.

Is it worth getting tax help if my return is simple?

Even a straightforward return can hide missed savings. A tax expert may identify credit deductions that a person could overlook. This is especially true if you recently moved, are self-employed, or own a home. Free help is often available from nonprofit programs or VITA sites, especially for seniors or lower-income people.

Can I still file a return if I missed the deadline in prior years?

Yes, you can file your Colorado tax returns from several years back. While you might not qualify for a refund after a specific period, you can still reduce tax liabilities or update records. If you previously paid for medical, school, or groceries that may qualify under past deductions, consult a tax expert to see what’s still available.