C.R.S. § 39-22-310

It is the intent of the general assembly that, in interpreting or construing the provisions of this part 3, statutes shall be given the strongest weight, then rules and regulations, and then the administrative interpretation or construction of said provisions by the executive director or the department of revenue; the administrative interpretation shall be given no greater weight than the interpretation of the taxpayer regardless of how long-standing such administrative interpretation or construction might be, unless such administrative interpretation or construction is set forth in rules and regulations promulgated by the executive director.