Colo. Rev. Stat. § 39-2-111
The administrator shall examine all complaints filed with him wherein it is alleged that a class or subclass of taxable property in a county has not been appraised or valued as required by law or has been improperly or erroneously valued or that the property tax laws have in any manner been evaded or violated. Complaints shall be in writing and may be filed only by a taxing authority in a county or by any taxpayer. Complaints may be filed only with respect to property located in the county in which the taxing authority levies taxes or in which the taxpayer owns taxable property. If the administrator finds the complaint is justified, he may use his findings as the basis for petitioning the state board of equalization for an order of reappraisal pursuant to section 39-2-114.
C.R.S. § 39-2-111