Updated July 2026
What Is Uninsured and Underinsured Motorist Coverage Insurance?
Uninsured motorist coverage (UM) pays when an at-fault driver has no insurance. Underinsured motorist coverage (UIM) pays when their liability limits fall short of your damages. Both cover medical expenses, lost wages, and vehicle repair costs up to your policy limits. You file the claim with your own carrier, not the at-fault driver's.
- A driver with no insurance rear-ends you at a stoplight. You have $8,000 in medical bills and $5,000 in vehicle damage. Their liability coverage would normally pay, but they carry none. Your UM coverage pays the $8,000 medical and your UIM pays the $5,000 vehicle damage, minus your deductible if your policy includes one.
- An at-fault driver carries Colorado's minimum liability limit of $25,000 per person. Your injuries total $60,000 in medical costs and lost wages. Their policy pays the $25,000 maximum. Your UIM coverage pays the remaining $35,000, up to your UIM policy limit.
- A driver sideswibes your car and flees. Witnesses provide a partial plate number, but police never locate the driver. If you carry UM coverage and can document the incident, your policy may cover medical bills. Your collision coverage handles the vehicle damage regardless of whether the other driver is found.
Who Needs Uninsured and Underinsured Motorist Coverage Insurance?
Carry UM/UIM if you drive in metro areas with high uninsured rates, if your health insurance has high deductibles or excludes auto accident injuries, or if you finance a vehicle and collision coverage alone won't cover a total loss caused by an uninsured driver. It's the only coverage that pays your medical bills when the at-fault driver has no insurance and you don't carry medical payments coverage.
Match your UM/UIM limits to your liability limits if you carry full coverage — a $100,000 liability policy with $25,000 UM leaves you underinsured if an uninsured driver causes serious injury. If your health insurance has a high deductible or excludes auto injuries, UM medical coverage fills that gap. Compare the annual premium to your health insurance deductible and your vehicle's value to decide if the cost justifies the protection.
How Much Does Uninsured and Underinsured Motorist Coverage Insurance Cost?
UM/UIM coverage typically adds $8 to $18 per month to a Colorado policy, or $96 to $216 annually, depending on your selected limits and whether you stack coverage across multiple vehicles.
- Your UM/UIM limit selection — matching your liability limits costs more but closes the coverage gap if an uninsured driver causes serious injury.
- Stacking election — stacked UM/UIM multiplies your per-vehicle limit by the number of insured vehicles, increasing both coverage and premium.
- Deductible structure — some Colorado carriers offer UM property damage with a deductible, reducing premium but requiring out-of-pocket payment before coverage applies.
- Collision coverage interaction — carriers price UM property damage lower if you already carry collision, since collision covers most hit-and-run vehicle damage.
- County uninsured driver rate — Denver and Pueblo counties have higher uninsured motorist rates than statewide averages, which can increase UM/UIM pricing.
- Claims history — prior UM claims signal higher risk to carriers and raise renewal premiums more than liability-only claims.