UM/UIM in Colorado: What It Really Covers

Uninsured and underinsured motorist coverage (UM/UIM) pays for your injuries when the driver who hit you has no insurance or not enough. In Colorado it comes with every auto policy unless you reject it in writing. Your insurer must also offer UM limits that match your own injury limits (C.R.S. § 10-4-609(1)-(2)). UIM pays on top of the other driver's limits, and it can't be reduced by what MedPay or health insurance already paid.

What are the key UM/UIM rules in Colorado?

1. 1. Included by default: every auto liability policy must carry UM unless the named insured rejects it in writing.
2. 2. Offered at your limits: the insurer must offer UM equal to your bodily injury liability limits.
3. 3. UIM is part of UM: the same coverage pays when the other driver is underinsured.
4. 4. Add-on, not offset: UIM pays the gap between the other driver's limits and your damages, up to your UM limit.
5. 5. No setoffs: MedPay, health insurance, and other coverage can't reduce it.
6. 6. Unlocatable drivers count as uninsured, in certain cases, for your UM claim.

Many Colorado drivers carry only the minimum liability coverage: $25,000 per person and $50,000 per accident for injuries, plus $15,000 for property (C.R.S. § 10-4-620). One ambulance ride, a night in the hospital, and a few months of therapy can pass $25,000 fast. When that happens, UM/UIM is often the difference between a fair recovery and an empty bag.

What is the difference between UM and UIM coverage?

UM, or uninsured motorist coverage, applies when the at-fault driver has no liability insurance, and under most policies when a hit-and-run driver can't be identified. UIM, or underinsured motorist coverage, applies when the driver has insurance but not enough to cover your injuries. Colorado folds UIM into UM coverage (C.R.S. § 10-4-609(4)). Both pay the bodily injury damages you are “legally entitled to recover” from the other driver: medical bills, lost pay, pain, and loss of enjoyment of life. Punitive damages are excluded, and car repairs fall under collision coverage instead.

How much will UIM pay after the other driver's limits run out?

Since 2008, Colorado UIM has worked as an add-on. C.R.S. § 10-4-609(1)(c) says it comes “in addition to” the other driver's limits. It pays the gap between their limits and your losses, up to your own UM limit. Here's a worked example with round numbers:

• • The other driver carries the $25,000 minimum.
• • Your medical bills, lost pay, and pain add up to $85,000.
• • Your UIM limit is $100,000 per person.
• • You collect the $25,000 limit from the other driver, then $60,000 from your UIM.
• • Without UIM, you would stop at $25,000.

Does UM cover a hit-and-run or a driver who can't be found?

Usually, yes. Most policies define an unknown hit-and-run driver as uninsured, so read the definition on your own policy. Colorado adds a specific rule in C.R.S. § 10-4-609(6). Say the other driver is known but can't be found to be served with a lawsuit after a real effort. That driver is treated as uninsured for your UM claim if one more thing is true. Either serving their insurer has failed, or the police report shows no insurer and nobody knows of one. The claim still needs proof, so a police report, witnesses, and video matter. Our hit-and-run guide covers the first 24 hours.

Can I stack UM/UIM coverage from more than one car?

Sometimes. Colorado lets an insurer limit a single policy that covers several cars for one premium to apply once per accident (C.R.S. § 10-4-609(1)(c)). Separate policies bought separately raise a different question, and the answer turns on the policy wording and who each policy covers. Bring every declarations page in your household to a consultation. People are often surprised to find more UIM than they thought.

How long do I have to bring a UM or UIM claim in Colorado?

Colorado sets a separate clock for UM and UIM claims in C.R.S. § 13-80-107.5. The base rule is three years after the claim accrues. If you preserve the claim against the at-fault driver in time, a UIM claim is also timely within two years after you receive the settlement or judgment payment. A UM claim gets two years after you learn the driver has no coverage. Either way, you never get less than three years. Many policies also require your insurer's consent before you settle with the other driver, so ask first.

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Your own UM carrier is still an insurance company, and it acts like one. The same medical record that proves your case against the other driver has to prove it to your insurer. I treat a UIM claim exactly like a liability claim, from the first chart note on.

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How can I make my UM/UIM claim stronger?

1. 1. Get care early and keep going. Gaps in treatment feed denial arguments.
2. 2. Log symptoms daily: headaches, sleep, light sensitivity, range of motion.
3. 3. Ask your doctor to write down work limits and daily-life limits.
4. 4. Be careful with statements. “I'm fine now” will come back later.
5. 5. Save dashcam files, phone location data, and neighbors' camera clips.
6. 6. Get your insurer's written consent before settling with the at-fault driver.

UM/UIM often decides what a serious crash case is really worth. If the driver who hit you had no insurance or too little, our uninsured motorist and underinsured motorist pages explain how we handle these claims. Our MedPay guide covers early medical bills. Start with a free consultation, or browse our personal injury practice pages.