Updated July 2026
What Is Uninsured and Underinsured Motorist Coverage Insurance?
Uninsured motorist coverage (UM) and underinsured motorist coverage (UIM) protect you when another driver causes a crash but can't pay for the damage. UM applies when the at-fault driver has no insurance at all. UIM applies when they have insurance, but their liability limits are too low to cover your medical bills, lost wages, or vehicle repair costs. Both coverages pay through your own insurance carrier, not the other driver's.
- You're stopped at a red light when another driver rear-ends you. You have $18,000 in medical bills and $9,000 in vehicle damage. The other driver has no insurance. Your $25,000 UM bodily injury coverage pays your medical costs up to the limit, and your $10,000 UM property damage coverage pays for vehicle repairs minus your deductible. Without UM coverage, you'd pay out of pocket or sue the uninsured driver directly—a process that rarely recovers anything.
- Another driver runs a stop sign and totals your vehicle. You have $22,000 in medical expenses and your car is worth $16,000. The at-fault driver carries Arizona's minimum liability limits: $25,000 per person for bodily injury and $15,000 for property damage. Their policy pays $25,000 for your injuries and $15,000 for your vehicle, leaving you $13,000 short. Your UIM coverage pays the gap up to your policy limits. Without UIM, you absorb the $13,000 loss.
- Your parked car is sideswiped overnight and the driver flees. Repairs cost $7,500. If you carry UM property damage coverage and collision coverage, you can choose which to file under. UM property damage often has a lower deductible. If you only have collision, you pay your collision deductible and your carrier covers the rest. UM coverage alone won't pay for hit-and-run vehicle damage unless the other driver is later identified and confirmed uninsured.
Who Needs Uninsured and Underinsured Motorist Coverage Insurance?
You should carry UM and UIM coverage if you drive frequently in areas with high uninsured driver rates, if you can't afford to pay medical bills or vehicle repairs out of pocket after a crash, or if you carry liability-only insurance and want protection for your own injuries. It's also critical if you finance or lease a vehicle—gap insurance won't help if the at-fault driver has no coverage and you're left owing more than the car is worth.
Compare the annual cost of UM/UIM coverage to your ability to pay $15,000–$30,000 in medical bills or vehicle repairs if another driver can't. If that amount would create financial hardship, the $95–$215 annual premium is justified. If your health insurance has high deductibles or doesn't cover lost wages, UM bodily injury coverage fills that gap.
How Much Does Uninsured and Underinsured Motorist Coverage Insurance Cost?
Adding UM and UIM coverage typically costs $8–$18 per month, or roughly $95–$215 annually, depending on your coverage limits and location.
- Coverage limits you select—higher UM/UIM limits cost more but close larger gaps when the other driver's insurance falls short.
- Your ZIP code—areas with higher uninsured driver rates or more frequent hit-and-run claims see higher UM premiums.
- Whether you stack coverage—stacking UM limits across multiple vehicles on one policy increases the total available coverage and raises the premium.
- Your carrier's claims experience—insurers that pay more UM claims in Arizona adjust pricing to reflect that risk.
- Bundling with collision and comprehensive—carriers often discount UM when you carry full coverage rather than liability-only.