Colorado Department of Revenue Fax Numbers: Tax, DMV, and Cover Sheets

The Colorado Department of Revenue fax number depends on which division you’re contacting. For DMV title and registration paperwork, fax (303) 205-5978.¹ For driver records and Driver Control forms, fax (303) 205-5949.² The taxation side is harder to pin down: CDOR’s main tax contact page does not publish a general fax line, so the number printed on your notice is the one to use, and if you don’t have a notice, call (303) 238-7378 to ask which fax line handles your matter.³

DMV Fax Numbers

Title transfers, insurance verification, and registration corrections all go to the Title and Registration section at (303) 205-5978.¹

Driver records, certified driving record requests, and court-ordered documents go to Driver Control at (303) 205-5949. Older directories sometimes list (303) 205-5730, but the current Driver Control contact page uses (303) 205-5949. If you want to confirm before sending, the Driver Control phone line is (303) 205-5809.²

Taxation Fax Numbers

CDOR’s taxation division routes fax traffic to internal units rather than one general line, and the main tax contact page does not publish a fax number.³ If you’re responding to a letter from the Department, check the notice itself. It will typically show a fax number for the unit handling your case, and individual income tax, sales tax, and withholding tax each route differently.

If you don’t have a notice in hand, call the tax information line at (303) 238-7378 to confirm the correct fax before sending. Taxpayer Service Representatives take calls Monday through Friday, 8:00 a.m. to 4:30 p.m. Mountain Time. Sending to the wrong number can land your documents in the wrong queue or lose them entirely.

What to Put on the Cover Sheet

A fax with no identification is a fax that goes nowhere. Every cover sheet should include your full legal name, your Social Security Number or Colorado Account Number, a daytime phone number, and a total page count that includes the cover sheet itself. If you’re responding to a notice, add the Source Code printed in the upper-right corner of the letter. That code is how the Department matches your submission to your file.⁴

Two forms come up often. The DR 0004 is the Colorado Employee Withholding Certificate for adjusting state tax withholding on your paycheck.⁵ The DR 0145 works as either a Tax Information Authorization or a Power of Attorney, depending on how you complete it.⁶ Both download from CDOR’s website.

Faxing a Response to a Tax Notice

When CDOR sends a notice, you can provide the requested documents or file a formal protest. Those are different actions. Sending documentation on its own does not preserve your right to protest the Department’s findings.⁴

If you’re protesting, your cover letter needs to include:

The Source Code from the upper-right corner of the notice
The tax periods in dispute
An itemized breakdown of the amounts and types of tax you disagree with
A written explanation of why you believe the tax is not owed
Whether you want a hearing with the Executive Director or prefer to submit a written brief
A signature from the taxpayer, a business officer, or someone with a valid power of attorney

You have 30 days from the mailing date of the notice to request a hearing or submit a written brief. The Department cannot extend this deadline; it’s set by §39-21-103(7), C.R.S.⁴ Faxing beats mailing when the clock is tight, because mailed submissions take four to six weeks to process.⁷

Keep the Transmission Confirmation

After a successful fax, your machine prints a transmission report showing the date, time, receiving number, and result. Keep that report with a copy of what you sent. If the Department later says nothing arrived and you’re near a filing deadline, the confirmation is your evidence that the documents went through.

Signature Requirements

For tax-related faxes, sign in ink first, then send. Colorado’s Department of Revenue requires an original signature from the taxpayer or an authorized representative on protest letters and powers of attorney.⁴ The IRS follows the same convention on faxed forms, generally requiring a handwritten signature rather than a typed name or digital mark. Print the document, sign it, then feed the signed pages through the machine.

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Colorado Department of Revenue. Contact Us – DMV
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Colorado Department of Revenue – Motor Vehicle. Contact Us – Driver Control
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Colorado Department of Revenue. Contact Us – Department of Revenue – Taxation
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Colorado Department of Revenue. Protest Rights and Process
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Department of Revenue – Taxation. DR 0004 – Colorado Employee Withholding Certificate
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Colorado Department of Revenue – Taxation. DR 0145 – Colorado Tax Information Authorization or Power of Attorney
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Colorado Department of Revenue. Contact Us By Mail