Colorado Revised Statutes Title 39. Taxation § 39-28-108. Penalty

(2)(a) If a person neglects or refuses to make a return as required by this article, the executive director of the department shall impose a penalty of one hundred dollars.

(b) If a person fails to pay the tax in the time allowed for the discount in section 39-28-104(1) or 39-28-103.3, a penalty equal to ten percent thereof plus one-half of one percent per month from the date when due, not to exceed eighteen percent in the aggregate, together with interest on such delinquent taxes at the rate computed under section 39-21-110.5, shall apply.

(c) In computing and assessing the penalty, penalty interest, and interest pursuant to paragraph (b) of this subsection (2), the executive director of the department may make an estimate, based upon such information as may be available, of the amount of taxes due for the period for which the taxpayer is delinquent.