Updated July 2026
What Is Uninsured and Underinsured Motorist Coverage Insurance?
Uninsured motorist coverage (UM) pays for your injuries and property damage when an at-fault driver has no insurance. Underinsured motorist coverage (UIM) pays the difference when the at-fault driver's liability limits are too low to cover your full losses. Both coverages apply only when the other driver is legally responsible for the crash — they don't cover your own mistakes or single-vehicle accidents.
- You're stopped at a red light in Honolulu when a driver without insurance rear-ends you at 35 mph. You have $8,000 in medical bills and $6,500 in vehicle damage. The at-fault driver has no coverage to pay your claim. Your UM coverage pays your medical bills up to your bodily injury limit, and your underinsured property damage coverage pays the $6,500 vehicle repair minus your deductible.
- A driver with Hawaii's minimum $20,000 bodily injury limit runs a stop sign and T-bones your car. You suffer a broken collarbone and miss six weeks of work, totaling $45,000 in medical bills and lost wages. The at-fault driver's $20,000 liability policy pays out in full, but you're still $25,000 short. If you carry $50,000 in UIM coverage, your policy pays the remaining $25,000 to cover your full loss.
- You carry Hawaii's minimum liability limits but no UM/UIM coverage. An uninsured driver causes a crash that leaves you with $30,000 in medical bills. Your liability coverage only pays for damage you cause to others — it provides zero protection when someone else hits you. You're responsible for the full $30,000 out of pocket unless you sue the uninsured driver and successfully collect, which is unlikely if they couldn't afford insurance.
Who Needs Uninsured and Underinsured Motorist Coverage Insurance?
You should carry UM/UIM coverage if you don't have health insurance that covers auto accident injuries, if you drive in areas with high uninsured driver rates, or if you financed your vehicle and can't afford to replace it out of pocket after a total-loss crash caused by an uninsured driver. It's also critical if you carry high liability limits — a driver with $100,000 in liability coverage who gets hit by someone with Hawaii's $20,000 minimum is underinsured by $80,000, and only UIM coverage closes that gap.
Match your UM/UIM limits to your liability limits if you want the same protection from other drivers that you provide to them. If you carry $100,000 in liability coverage, carry $100,000 in UM/UIM — otherwise you're protected against drivers with less coverage than you carry, but not against drivers who match your limits and cause a serious crash.
How Much Does Uninsured and Underinsured Motorist Coverage Insurance Cost?
UM/UIM coverage typically adds $8 to $18 per month to a Hawaii auto insurance policy, or $96 to $216 annually, depending on your selected limits and whether you match your liability limits or purchase lower UM/UIM limits.
- Your UM/UIM coverage limits — matching your liability limits costs more than purchasing lower UM/UIM limits, but protects you against drivers carrying the same coverage you carry.
- Whether you add UM property damage coverage — some Hawaii insurers include it automatically, others charge an additional $3 to $6 per month to cover vehicle damage from uninsured drivers.
- Your ZIP code's uninsured driver rate — areas with higher uninsured motorist rates see slightly higher UM/UIM premiums because claims are more frequent.
- Stacking versus non-stacking coverage — stacking allows you to combine UM/UIM limits across multiple vehicles on your policy, which increases your total available coverage and raises your premium by 15% to 25%.
- Your claims history — a prior UM/UIM claim may increase your premium at renewal, though the increase is typically smaller than an at-fault accident surcharge.