Updated July 2026
What Is Uninsured and Underinsured Motorist Coverage Insurance?
Uninsured motorist coverage (UM) pays when the driver who hits you has no insurance. Underinsured motorist coverage (UIM) pays when their liability limits are too low to cover your full damages. Both come as a package—you can't buy one without the other. The coverage applies to bodily injury and, if you add the property damage endorsement, to vehicle repair costs your collision coverage doesn't handle.
- You're stopped at a red light. The driver behind you doesn't brake and hits you at 35 mph. You have $8,000 in medical bills and $6,500 in vehicle damage. The other driver has no insurance. Your UM bodily injury coverage pays the $8,000 in medical costs. If you added UM property damage, it pays the $6,500 repair bill minus your deductible. Without UM/UIM, you pay both out of pocket or sue a driver who likely has no assets.
- Another driver runs a stop sign and T-bones your car. You suffer a broken collarbone and need surgery. Total medical bills: $42,000. The at-fault driver carries Washington's minimum liability limit of $25,000 per person. Their insurer pays the $25,000 maximum. Your UIM coverage pays the remaining $17,000. Without UIM, you're responsible for that $17,000 gap unless you want to spend years in court chasing someone who already proved they carry minimum coverage.
- A driver sideswiped your car on I-5 and fled. You didn't get the plate, but your passenger saw the vehicle make contact and your door has paint transfer. You file a police report. Your UM property damage coverage pays for the $4,200 in repairs minus your deductible. If the other car had swerved into your lane and caused you to crash into a guardrail without making contact, UM wouldn't apply—you'd need collision coverage for that scenario.
Who Needs Uninsured and Underinsured Motorist Coverage Insurance?
You should carry UM/UIM if you can't afford to cover a $30,000 medical bill or total loss vehicle replacement out of pocket. It's especially valuable if you carry liability-only coverage and skip collision—UM property damage becomes your only way to recover repair costs when an uninsured driver hits you. If you have passengers regularly—kids, carpool riders, elderly parents—UM bodily injury protects them when the other driver's limits run out.
Compare the annual UM/UIM premium to your collision deductible plus your health insurance out-of-pocket maximum. If the coverage costs less than 10% of that combined exposure, buy it. If it costs more, and you already have collision and health coverage, you're paying for overlapping protection. Check your state's uninsured driver rate—if it's above 10%, the odds justify the cost even with other coverage in place.
How Much Does Uninsured and Underinsured Motorist Coverage Insurance Cost?
Adding UM/UIM bodily injury coverage typically costs $8–$18 per month in Washington, or $96–$216 annually. Adding UM property damage increases that by another $3–$8 per month.
- Your UM/UIM limits—most carriers let you match your liability limits, so choosing $100,000 per person costs more than $25,000 per person.
- Whether you add UM property damage coverage as an endorsement—bodily injury UM/UIM is standard, but property damage is optional and priced separately.
- Your ZIP code's uninsured driver rate—King County and Spokane County have different uninsured motorist percentages, and carriers price accordingly.
- Whether you stack coverage across multiple vehicles on your policy—stacking multiplies your per-person limit by the number of insured cars, and costs 30–60% more.
- Your claims history—filing a UM claim can affect future premiums the same way an at-fault collision claim does, even though you weren't at fault.