DOR Taxation web site

Protest Rights

You received a Notice of Deficiency or Rejection of Refund Claim from the Department. Now what should you do?


Follow the 3 Rs: Review, Research and Respond/Remit


1. Review. Review the Notice and compare it to your corresponding tax return. You should be able to see what changes the Department made.


2. Research. Research the change to see if it is accurate. Our FYI Publications can help you more fully understand the nature of the tax or credit that was modified. Another good source of information is the annual tax booklet that corresponds to your return.


Once you understand why you received the Notice:


3. Respond or Remit.


Respond if you do not agree with the changes made by the department. 


The Notice you received should inform you what documentation the department requires you to send. If not please see our FYI publications and tax booklets for more information. Be sure to enclose a copy of your Notice with your response, and a cover letter that includes the following:


  • Name and address of taxpayer
  • Source Code (code listed in the upper right of the letter)
  • The taxable period(s) involved
  • The amount(s) and kind(s) of tax in dispute
  • An itemized schedule of the findings with which the taxpayer does not agree
  • A statement summarizing the reasons the taxpayer believes the tax is not due
  • Affirmative or negative determination of taxpayer to use brief in lieu of hearing as provided in §39-21-103(7), C.R.S.
  • Taxpayer signature*

*Signature can be the named individual taxpayer, general partner of a partnership, officer of a named corporation, or an individual authorized by such proper person's power of attorney. If the written brief is prepared by counsel, counsel must also sign.

 You can also submit your protest online through our Revenue Online service.

The Department will review your case in the order in which it was received. Depending on the Department's caseload and nature of your case, it may take up to six months for a response to your protest.


You have the right to a hearing with the Executive Director, or you may file a written brief in lieu of the hearing. However, you have only 30 days from the date of the Notice to request a hearing or to file your written brief. By law this requirement cannot be extended or negotiated by the Department.




Remit your payment if you agree with the changes. Several payment options are available.


Mail any correspondence to:

Colorado Department of Revenue
Denver CO 80261


Should you still have questions regarding your Notice you may speak to a Department representative by contacting us.