How to Pay Colorado State Income Taxes
Where Colorado state income tax payments go and how they move
Colorado state income tax is collected by the Colorado Department of Revenue, not by your employer or a third party. If you owe tax when you file your return, you send payment directly to the state. If your employer withholds too much, you receive a refund. The state accepts payments through its online portal, by mail, by phone, or through a tax professional.
The payment method you choose affects when the state receives your money and when your account is credited. Electronic payments (online or by phone) clear within one business day. Mailed checks take seven to ten business days to arrive and process. If you miss the tax deadline, penalties and interest begin accruing immediately, even if your payment is in transit.
Key Takeaways
- Colorado state income tax payments go to the Colorado Department of Revenue, and you can pay online through their portal, by phone, by mail, or through a tax professional.
- The tax deadline is April 15 unless it falls on a weekend or holiday, and the state counts the postmark date for mailed payments but the transaction date for electronic payments.
- If you cannot pay by the deadline, you can request a payment plan or extension directly from the Department of Revenue, and penalties will be lower if you file your return on time even if you pay late.
- Electronic payments clear within one business day, while mailed checks take seven to ten business days, so timing matters if you are close to the deadline.
- Colorado offers a payment plan for amounts you cannot pay in full, and the state charges interest on unpaid tax from the original due date.
Paying online through the Colorado Department of Revenue portal
The fastest and most direct route is the Colorado Department of Revenue's online payment system. You visit the state's website, enter your Social Security number or federal employer identification number, the tax year, and the amount owed. The system accepts payments by debit card, credit card, or electronic bank transfer (ACH). Credit card and debit card payments incur a convenience fee, usually between 1.5 and 2 percent of the payment amount. ACH transfers have no fee.
Once you submit an electronic payment, the state receives it within one business day. Your account is credited immediately, and you receive a confirmation number. Keep this number for your records. If you are paying close to the April 15 deadline, electronic payment is the safest option because the transaction date—not the date you initiate it—is what counts toward meeting the deadline.
Paying by phone or through a tax professional
You can also pay by phone through an automated system or a representative. The phone number appears on your tax notice and on the Department of Revenue website. Phone payments work the same way as online payments: you provide your tax information and payment method, and the transaction clears within one business day. A convenience fee applies if you use a credit or debit card.
If you work with a tax professional—a CPA, tax attorney, or enrolled agent—they can submit your payment on your behalf through their own system. The timing and fees depend on the method they use. Ask your tax professional whether they charge a separate fee for payment processing and whether they will submit the payment electronically or by mail.
Paying by mail and understanding postmark dates
If you mail a check, the Colorado Department of Revenue's address appears on your tax notice. The state counts the postmark date as your payment date, not the date they receive the check. This means a check postmarked April 15 is considered on time even if it arrives on April 22. However, mailed checks take seven to ten business days to clear, so if you mail payment after April 10, you are relying on the postal service to deliver and postmark it on time.
Include your Social Security number or federal employer identification number and the tax year on the check itself. Do not send cash. If your check is lost or delayed, you will not know for several weeks, and the state will assess penalties and interest from April 15 onward. For this reason, mailing is the riskiest option if you are close to the deadline.
Payment plans and extensions if you cannot pay in full
If you owe tax but cannot pay by April 15, you can request a payment plan directly from the Colorado Department of Revenue. A payment plan allows you to pay the balance over several months. The state charges interest on the unpaid balance from the original due date (April 15), regardless of when you pay. You must file your tax return by the deadline even if you cannot pay; filing on time and paying late results in lower penalties than filing late.
You can also request an extension to file your return, which gives you until October 15 to submit your return to Colorado. However, an extension to file is not an extension to pay. Tax is still due on April 15, and interest and penalties accrue on any unpaid balance from that date forward. The extension only delays when you must submit your return, not when you must pay.
What happens if you miss the deadline and do not pay
If you do not pay by April 15 and do not have an approved payment plan, the Colorado Department of Revenue assesses a failure-to-pay penalty of 0.5 percent of the unpaid tax per month, up to 25 percent total. Interest accrues at a rate set by the state each quarter, currently in the range of 8 to 10 percent annually, though this varies. Both penalties and interest compound, meaning you owe interest on the interest.
The state can place a lien on your property, garnish your wages, or intercept your federal refund to collect unpaid Colorado tax. If you receive a notice of intent to levy, you have a limited time to respond or request a hearing. The sooner you contact the Department of Revenue and arrange a payment plan, the lower your total cost will be.
Estimated tax payments if you are self-employed or have other income
If you are self-employed, own a business, or receive income that is not subject to withholding, Colorado requires you to make estimated tax payments four times per year. These payments are due on April 15, June 15, September 15, and January 15 of the following year. You calculate your estimated tax based on your expected income for the year and pay one quarter at a time.
Estimated payments are made through the same online portal, by phone, or by mail as regular tax payments. If you underpay your estimated tax, you may owe a penalty when you file your annual return, even if you pay the full amount owed by April 15. The penalty is based on how much you underpaid each quarter and how late that payment was. Paying estimated tax on time reduces or eliminates this penalty.
Frequently Asked Questions
What is the Colorado state income tax deadline?
The deadline is April 15 each year, unless it falls on a weekend or holiday, in which case it moves to the next business day. This is the same deadline as federal income tax. The state counts the postmark date for mailed payments and the transaction date for electronic payments.
Can I pay Colorado state tax with a credit card?
Yes, but a convenience fee of 1.5 to 2 percent applies. You can pay online, by phone, or through a tax professional. ACH bank transfers have no fee and are the cheapest electronic option if you have time before the deadline.
What if I owe Colorado tax but also owe federal tax?
Colorado and federal taxes are separate. You pay each to its own agency by its own deadline. The Colorado Department of Revenue does not collect federal tax, and the IRS does not collect Colorado tax. Paying one does not affect the other.
Can the state take my federal refund if I owe Colorado tax?
Yes. If you owe unpaid Colorado tax and do not have an approved payment plan, the state can request that the federal government intercept your federal refund and apply it to your Colorado debt. This is called tax offset. You will receive notice before this happens.
Do I have to file a Colorado return if I only work in Colorado but live in another state?
Colorado taxes income earned in the state, regardless of where you live. If you worked in Colorado during the year, you must file a Colorado return and pay tax on that income, even if you also file a return in your home state. Some states offer a credit for taxes paid to other states to avoid double taxation.