Uninsured and Underinsured Motorist Coverage, Explained
About 1 in 7 drivers is uninsured. What uninsured and underinsured motorist coverage pays, which states require it and how to choose your limits.
Updated October 7, 2026 · 6 min read
Key takeaways
- Uninsured motorist coverage (UM) pays for your injuries when the at-fault driver has no insurance or it's a hit-and-run.
- Underinsured motorist coverage (UIM) pays when the at-fault driver's limits are too low to cover your costs.
- About 15.4% of drivers, more than 1 in 7, were uninsured in 2023, according to the Insurance Research Council.
- About 20 states plus D.C. require UM or UIM, and many others require insurers to offer it.
What UM and UIM cover
Your liability insurance pays for damage you cause to other people. It does nothing for you if someone else causes the crash and can't pay. That's where these coverages come in:
- Uninsured motorist (UM) pays your medical bills, lost wages and pain and suffering when the at-fault driver has no insurance, and in most states when a hit-and-run driver can't be found.
- Underinsured motorist (UIM) pays when the at-fault driver has insurance, but not enough. If they carry a $25,000 limit and your injuries cost $60,000, UIM can help cover the rest, up to your limit.
- Uninsured motorist property damage (UMPD), available in some states, pays to repair your car when an uninsured driver hits it, usually with a small deductible.
How common uninsured drivers are
The Insurance Research Council estimates that 15.4% of drivers were uninsured in 2023. The rate varies widely by state: Mississippi was highest at 28.2%, while Maine was lowest at 5.7%. In some states, more than one in five drivers on the road has no coverage.
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Which states require it
According to the Insurance Information Institute, about 20 states plus Washington, D.C. require uninsured or underinsured motorist coverage. Many other states require insurers to include it unless you reject it in writing. A few, like Ohio, don't even require insurers to offer it. See your state's rules in our car insurance by state guide.
How much UM/UIM to buy
A common rule of thumb is to match your UM/UIM limits to your own liability limits. If you carry 100/300 bodily injury liability, consider 100/300 UM/UIM. The coverage protects you and your passengers, and it's usually one of the less expensive parts of a policy.
Don't reject it without thinking
When you sign a rejection form, you give up the protection that pays when the other driver can't. If you have health insurance, it may cover some medical bills, but it won't replace lost wages or pay for pain and suffering. Get a quote with UM/UIM included before you decide to drop it.
Frequently asked questions
Does uninsured motorist coverage pay for hit-and-run accidents?
In most states, yes, for injuries. Rules for vehicle damage in hit-and-runs vary by state and policy.
Do I need UM if I have health insurance?
Health insurance may pay medical bills, but it won't cover lost wages or pain and suffering, and it may not cover your passengers. UM covers those.
What is stacking?
In some states you can combine UM/UIM limits across multiple vehicles for higher coverage. It costs more but raises your protection.
Sources
How this guide was made: researched and drafted with AI assistance (Wren AI), and checked against the government and industry sources listed above. Wren AI is an AI tool, not a person or a licensed insurance agent.
This guide is general information, not insurance, legal or tax advice. Coverage, rules and prices vary by state, insurer and policy. Confirm details with a licensed agent before you buy. Read our editorial policy.