C.R.S. 10-4-609: what the statute requires
Colorado auto insurers must provide coverage protecting people insured under the policy who are, in the statute's language, "legally entitled to recover damages from owners or operators of uninsured motor vehicles" (C.R.S. 10-4-609(1)(a)(I)).
The coverage can be declined, but the statute permits rejection only where the named insured rejects it in writing. A rejection that does not satisfy the statute may be ineffective, which can mean coverage exists on a policy the insured believed carried none. That form is worth reading before anyone concludes there is nothing to claim against. A driver working for a transportation network company cannot reject the coverage during a prearranged ride.
For underinsured claims the statute provides that the coverage "shall cover the difference, if any, between the amount of the limits of any legal liability coverage and the amount of the damages sustained," and then adds the sentence that decides most disputes: "The amount of the coverage available shall not be reduced by a setoff from any other coverage." Colorado UIM stacks on top of the liability payment instead of absorbing it.
Whether limits from more than one vehicle or policy can be combined is separate and fact-specific. The statute permits a single policy or endorsement issued for a single premium covering multiple vehicles to be limited to applying once per accident, so the answer depends on the declarations pages, how premiums were charged, and the policy wording.
The four situations where UM/UIM applies
No liability insurance at all. Your UM coverage may be the only realistic source of payment.
Hit-and-run. Under C.R.S. 10-4-609(6), an alleged tortfeasor is treated as uninsured where that person cannot be located for service, or where insurance coverage cannot be identified through reasonable effort.
A driver who caused the crash without contact. A vehicle forces you into a barrier or another lane and continues on. These claims can proceed, and corroborating evidence such as an independent witness or camera footage is typically expected.
An underinsured driver. The other driver had a policy, but the limit sits below your documented losses. Their carrier pays its limit and the UIM claim addresses the shortfall up to your own limit.
The filing deadline and comparative fault
Colorado UM/UIM claims are governed by C.R.S. 13-80-107.5, the statute the Colorado Supreme Court applied in Pham v. State Farm Mutual Automobile Insurance Co., 2013 CO 17. The general period is three years after the cause of action accrues. The statute adds periods tied to the underlying claim: for UM, two years after the insured knows the particular tortfeasor is not covered; for UIM, two years after the insured received payment of a settlement or judgment. It also provides a floor, that in no event shall the insured have less than three years after the cause of action accrues.
Accrual is not simply the date of the crash. Subsection (3) ties it to when both the injury and its cause "are known or should have been known by the exercise of reasonable diligence."
Which of those periods controls depends on the procedural history of the claim, and the policy itself may carry a shorter contractual notice requirement. Late notice is a defense insurers raise, so the deadlines belong on the table in the first week.
Colorado applies modified comparative negligence under C.R.S. 13-21-111, which permits recovery where the claimant's negligence "was not as great as the negligence of the person against whom recovery is sought." A claimant assessed at 50 percent or more recovers nothing, and any lower share reduces the award proportionally. On a UM/UIM claim it is your own carrier making that argument.
