C.R.S. § 40-10.1-107

(1) Each motor carrier shall maintain and file with the commission evidence of financial responsibility in such sum, for such protection, and in such form as the commission may by rule require as the commission deems necessary to adequately safeguard the public interest. (2) The financial responsibility required by subsection (1) of this section must be in the form of a liability insurance policy issued by an insurance carrier or insurer authorized to do business in this state, or a surety bond issued by a company authorized to do business in this state, or proof of self-insurance. (3) An insurance policy, surety bond, or self-insurance pursuant to subsection (2) of this section shall be kept continuously effective during the life of a certificate or permit and the commission shall require such evidence of continued validity as the commission deems necessary. (4) No termination of an insurance policy or surety bond is valid unless the insurer or surety has notified both the holder of the policy or bond and the commission at least thirty days before the effective date of the termination.