Contact Us

Contact Us by Email, Phone, and Fax

Taxpayer Helpline: (303) 238-7378

  • Taxpayer Service Representatives are available Monday through Friday, 8:00 a.m. to 4:30 p.m. (except on state holidays).

Other Contact Phone Numbers:  

Electronic Payment/EFT Help

Phone: 303-205-8333
Report Tax Evasion, Fraud or Scams- Please call this number if you believe you are a victim of fraud or a scam.
Phone: 303-205-8262
Bankruptcy-Please contact this section only if you have an active case already filed in bankruptcy court.
Phone: 303-866-3711
Collections- The Collections Section can assist with payments, payment plans, wage/bank garnishments, judgments, liens, and third-party collection agencies.
Phone: 303-205-8291
Fax: 303-866-2037
Hours: Mon-Thurs 8am-4:30pm, Fri 9am-4:30pm
Automated Collection Services, Inc. (ACSI)
Integral Recoveries, Inc. (IRI)
General Tax Questions
Phone: 303-238-7378
Email: - Please allow 3-4 business weeks for an email response for general tax inquiries. For a faster response, please call the general tax phone number or come in to one of the service center locations listed below. 
Compliance-The Compliance section can assist with outstanding tax debt for businesses.
Criminal Tax Investigations
Discovery-The Discovery Section can assist with tax adjustments and estimated returns based on third-party data. The Discovery Fraud Section can assist with taxpayer verification.
Phone: 303-205-8292
Fax: 303-866-3018
Hours: Mon-Fri, 8am-5pm, Walk-in service ends at 4:30pm
Excise Tax (cigarette and tobacco products tax and licensing, liquor excise tax, master settlement agreement, prepaid wireless fee, public utility administration fee)
Phone: 303-205-6848 or 303-205-6879

Fuel Tax (fuel excise, IFTA, aviation sales tax, exempt fuel, passenger mile tax)
Phone: 303-205-8205
Marijuana Tax
Field Audit
Phone: 303-692-7981
Tax Professionals Hotline
Phone: 303-232-2419

Sign Up for Tax News and Updates by Email

Subscribe to our free email subscription service to receive notifications when new tax information is available. With a subscription, you automatically receive updates without having to return to the website and check for changes. Email updates are a free service provided by CDOR. Your email address will only be used to deliver the information you've requested. 

Contact Us by Mail

Correspondence - Letters & Protests

U.S. Postal Service
Colorado Department of Revenue
Section or Employee Name and Room Number
P.O. Box 17087
Denver, CO 80217-0087
Express Mail Delivery – DHL, FedEx, UPS, etc.
Colorado Department of Revenue
Section or Employee Name and Room Number
1375 Sherman Street
Denver, CO 80203

Tax Payments

Be sure to include the payment form/voucher and mail payments to:
Colorado Department of Revenue
Denver, CO 80261-0004

Please note the following when sending correspondence and payments to the Colorado Department of Revenue:

  • The zip code 80261 is exclusive to the Colorado Department of Revenue. As a result, a street address or box number is not required when mailing forms or payments to 80261 via USPS First Class Mail. Be sure to add the zip code + 4 digits (80261-XXXX) to ensure proper delivery and payment processing.
  • Be sure to check the letter you received or your tax form for the correct mailing address first! If there is an address noted, be sure to send your correspondence and/or payment to the address on the form or letter.
  • Be advised that sending correspondence and/or payments without proper postage or via certified mail may delay the delivery of your mail, which may cause due dates to be missed.
  • Do not combine correspondence, payments and/or tax forms (other than payment forms/vouchers) in the same envelope.  Each of these requires special handling, so they must be sent separately and must be routed to the proper address. 

More information on mailing Tax Forms and Returns can be found on the Mail a Form web page.


Service Center Locations

When visiting our offices, it is important to note that you should bring your government-issued photo ID or driver license.  At this time, our office staff cannot accept cash or credit card payments.  All hand-delivered payments must be made with a check or money order, or to release a garnishment, a certified check. Please not that all service center locations are closed on state holidays

1375 Sherman St.
Denver CO 80203
Hours: Mon-Fri, 8am-5pm
Parking is limited to paid meters and lots, and is quite limited January – May during the legislative session.   
Colorado Springs 
2447 N. Union Blvd.
Colorado Springs CO 80909
Hours: Mon-Fri, 8am-5pm 
Fort Collins
3030 S. College Ave.
Ft. Collins CO  80525
Hours: Mon-Fri, 8am-5pm (closed for lunch from 12-1pm)
Grand Junction
222 S. 6th St., Room 208
Grand Junction CO  81501
Hours: Mon-Fri, 8am-5pm
827 W. 4th St., Suite A
Pueblo CO 81003
(Inside the DMV)
Hours: Mon-Fri, 8am-5pm

Citizen's Advocate

The Governor’s Office of Constituent Services ensures each State Department has a Citizen Advocate.  The Citizen Advocate is different from a Taxpayer Advocate in that they can assist in all divisions with the Department of Revenue including Enforcement, Lottery, Motor Vehicle and Taxation.  The advocate helps navigate concerns to Revenue management when normal methods for resolving issues or disputes have been ineffective.  Concerns are tracked to ensure a   prompt response.  Rules, regulation and statute can sometimes limit outcomes; however, the advocate will provide specifics.  We are restricted from providing any legal advice.  If this is your first attempt to resolve a problem, please use   one of our other contact methods listed above. The advocate will coordinate and facilitate a resolution with the appropriate division, generally within three working days.

ADA Accomodations

Relay Colorado is a free service for people with hearing or speech loss to communicate with standard telephone users.  Relay Colorado is available 24 hours per day, 365 days per year.
        Simply dial 711 to get connected
        TTY/TeleBraille 800-659-2656
        Voice 800-659-3656