If a Colorado driver chooses not to maintain an insurance policy on his or her vehicle, the driver must

If a Colorado driver does not wish to maintain an automobile insurance policy as required by state law, he or she must obtain a certificate of self-insurance from the Division of Motor Vehicles. [Financial Responsibility Law/Compulsory Insurance, Understanding Colorado's Motor Vehicle Laws, Colorado Driver Handbook] Note, however, that this option is only available to residents and businesses that own at least 25 vehicles. [Registration Requirements, Colorado Department of Revenue, Division of Motor Vehicles website]