Key Takeaways
Uninsured & Underinsured Motorist Coverage
Uninsured motorist (UM) coverage pays for your injuries and, in some states, vehicle damage when you're hit by a driver who carries no auto insurance. Underinsured motorist (UIM) coverage steps in when the at-fault driver has insurance, but their policy limits aren't high enough to cover your full losses. Together, these coverages protect you from financial harm caused by someone else's inadequate insurance decisions.
UM/UIM coverage is often split into bodily injury (UM/UIM BI) and property damage (UM/UIM PD) components, each with separate limits and, in some states, separate deductibles. Some policies also include uninsured motorist coverage for hit-and-run accidents, though this varies by insurer and state law.
Why This Coverage Exists
Every state requires drivers to carry liability insurance, yet millions don't. The Insurance Research Council has estimated that approximately one in eight drivers on U.S. roads is uninsured. That figure climbs higher in certain states. Even among insured drivers, many carry only the bare state-required minimums — limits that can be exhausted quickly by a single emergency room visit.
UM/UIM coverage was designed to fill exactly this gap. Rather than leaving you to pursue an at-fault driver in civil court — a process that can take years and still yield nothing if the driver has no assets — your own insurer steps in and compensates you as if it were the at-fault party's insurer. It is, in effect, insurance against other people's lack of insurance.
For a deeper look at what state minimums actually cover and why they often fall short, see our breakdown of state minimums vs. full coverage.
~1 in 7
Estimated share of U.S. drivers who are uninsured
According to Insurance Research Council estimates, a significant portion of drivers on American roads carry no auto insurance at any given time.
$25,000
Common state minimum bodily injury liability limit
Many states set their required per-person liability minimum at $25,000 — a figure that can be consumed by a single emergency room visit for a serious injury.
How UM and UIM Coverage Each Work
Uninsured motorist (UM) coverage responds when the driver who caused your accident carries no insurance at all. This includes most hit-and-run situations, depending on your state's rules and policy language. UM bodily injury pays for your medical treatment, lost wages, pain and suffering, and rehabilitation costs. UM property damage — where available — pays to repair or replace your vehicle.
Underinsured motorist (UIM) coverage handles a different scenario: the at-fault driver has insurance, but their policy limits are lower than your total damages. For example, if your medical bills total $80,000 but the at-fault driver carries only $25,000 in bodily injury liability, your UIM coverage can cover the remaining $55,000 up to your own UIM limit.
The two coverages are usually sold together and listed as a single line item on your policy declarations page with split limits (e.g., $100,000 per person / $300,000 per accident) or a combined single limit. It's worth understanding how UM/UIM fits alongside liability, collision, and comprehensive coverage on a complete policy.
Check Your Declarations Page for UM/UIM Limits
Your policy's declarations page lists every coverage type and its corresponding limit. If you don't see UM or UIM listed, you may not be carrying it — especially if you're in a state where it's optional. A quick review now can reveal gaps before an accident makes them costly.
Common Situations Where It Applies
UM/UIM is not a theoretical coverage. It activates in everyday accidents that can happen to any driver.
It's also worth noting that pedestrians and cyclists struck by an uninsured driver may be able to claim under their own auto policy's UM coverage in many states — the coverage isn't exclusively for occupants of a vehicle.
What to Consider When Choosing Your Limits
Because your UM/UIM coverage must substitute for someone else's liability coverage, a useful starting point is to mirror your own liability limits. If you carry $100,000/$300,000 in liability, matching those figures for UM/UIM ensures you're protected to the same degree you protect others.
Consider these factors when evaluating your limits:
- Medical costs: Serious injuries involving surgery, hospitalization, or long-term rehabilitation can generate six-figure bills rapidly.
- Lost income: UM/UIM bodily injury can compensate for wages lost while you recover — higher limits help if you have significant earning capacity.
- Assets at risk: If you have substantial savings or property, inadequate coverage could leave you absorbing costs your insurer won't pay.
- Stacking rules in your state: Some states allow you to stack limits across multiple insured vehicles, effectively multiplying your available coverage.
Discussing limits with a licensed insurance agent is the most reliable way to match coverage to your actual financial exposure. For help structuring that conversation, see how to have a more informed conversation with your insurance agent.
This article provides general educational information about auto insurance coverage and is not personalized insurance, financial, or legal advice. Coverage terms, availability, and requirements vary by state and insurer. Always read your policy documents carefully and consult a licensed insurance professional for guidance specific to your situation.