What Is Uninsured Motorist Coverage?

Uninsured motorist coverage pays you when the driver who hit you can't. It sits on your own policy, it steps in when the at-fault driver has no insurance (or has fled), and its underinsured twin steps in when the at-fault driver has some insurance but not enough. In most states it's the only coverage on your policy that pays for your injuries when the other driver has nothing, and in a few it's the only thing that pays for your car.

The reason it exists is simple arithmetic. The Insurance Research Council estimates that 15.4% of U.S. drivers were uninsured in 2023, about one in seven, ranging from 5.7% in Maine to 28.2% in Mississippi, per the National Association of Insurance Commissioners. Liability insurance only works if the other driver bought some. This coverage is for the one-in-seven chance they didn't.

The four coverages hiding under one name

"Uninsured motorist coverage" is usually a bundle of up to four things, and states slice it differently:

• Uninsured motorist bodily injury (UMBI): your medical bills, lost wages and pain and suffering when an uninsured driver injures you or your passengers. This is the core coverage, and the one states mandate when they mandate anything.
• Underinsured motorist bodily injury (UIMBI): the same, when the at-fault driver has insurance but their limits run out before your bills do. A driver carrying a 25/50 state minimum who puts you in the hospital for a week is underinsured almost by definition.
• Uninsured motorist property damage (UMPD): damage to your car from an uninsured driver. Not available in every state, often capped, and sometimes excluded for hit-and-runs.
• Underinsured motorist property damage (UIMPD): the rarest of the four; most states fold it into UMPD or don't offer it.

Insurers sell the bodily-injury pair together as "UM/UIM" and price it by the limit you pick, usually matched to your liability limits. The Insurance Information Institute notes that prices vary considerably by state, driven mostly by how many local drivers are uninsured and by whether the state allows "stacking": multiplying the limit by the number of cars on the policy, which about half the states prohibit.

Required, offered, or optional: the three rules

Every state handles this coverage one of three ways, and the way your state does it decides whether you have it without ever having chosen it.

1. Required. About 20 jurisdictions make UM coverage compulsory, per the Insurance Information Institute, and only a handful add UIM. If you have a policy in one of them, you have this coverage.
2. Rejected only in writing. Insurers must include it or offer it, and the only way to go without it is a signed rejection. Texas, Georgia, Louisiana and Kentucky put it in every policy by default; Oklahoma, Alabama and Pennsylvania make insurers offer it and require the rejection in writing. Most drivers in these states have the coverage and don't know it; the ones who don't signed something.
3. Must be offered, optional. Insurers have to offer it and you can decline. Arkansas, California, Nevada, New Mexico and Florida work this way. The coverage shows up on the quote; whether it stays on the policy is up to you.

Here is where our 30 guide states fall, with each state's estimated share of uninsured drivers from the Insurance Research Council's 2022 study as published by the Insurance Information Institute:

Two things stand out. The states with the most uninsured drivers are mostly the ones that don't require the coverage; New Mexico, Tennessee and Georgia all sit near the top of the uninsured list, and none of them makes drivers carry it. And "not required" never means "not available": the Insurance Information Institute notes that in states without a mandate, insurers are generally required to offer the coverage anyway, so it's a question of whether you kept it, not whether you could get it.

Written rejection up close: Texas and Oklahoma

Texas is the clearest case. Under Texas law, insurers must offer uninsured/underinsured motorist coverage with every auto policy, and if you don't want it, you have to turn it down in writing, per the Texas Department of Insurance. The coverage pays your car repairs and medical bills after a crash with a driver who has little or no insurance, including a hit-and-run where the other driver can't be found. Car repairs carry a $250 deductible, usually well under a collision deductible. TDI puts the state's uninsured share at 12% of registered vehicles. Our Texas guide covers the rest of the state's "included unless declined" wrinkle, which also applies to $2,500 of personal injury protection.

Oklahoma works the same way for the bodily-injury coverage: insurers must offer it at the state's 25/50 liability limits, and you can only decline it in writing, per the Oklahoma Insurance Department as cited in our Oklahoma guide. The department's own explanation for Oklahoma's rates leans on the state's share of uninsured drivers, which is the argument for keeping the coverage you'd otherwise have to sign away. Oklahoma sells uninsured motorist property damage as a separate optional add-on, which matters below.

Arkansas sits one step looser: insurers must offer both UM/UIM and PIP, and both are optional, per our Arkansas guide. Arkansas's shared-fault rule, which cuts your recovery from the other driver by your share of the blame and eliminates it at 50%, makes your own policy do more of the work there than in most states, which is why the guide's first piece of advice is to keep the coverage even though you don't have to.

Hit-and-runs: the exception that varies most

A hit-and-run is where this coverage either shines or quietly fails, depending on the state.

The general rule, per the Insurance Information Institute, is that uninsured motorist coverage treats an unidentified hit-and-run driver as uninsured. If you have UM bodily injury coverage and a driver hits you and flees, your injuries are covered up to your limit. Texas spells this out: TDI says the coverage pays if you're in a hit-and-run and the other driver can't be found, with the $250 deductible on the car.

The property-damage side is where it gets state-specific:

• California requires insurers to offer uninsured motorist property damage, but it's capped at $3,500 and pays only when the uninsured driver is identified. A hit-and-run that damages your car falls to your collision coverage, or to you. For injuries, California's statute requires actual physical contact between the fleeing vehicle and you or your car before a hit-and-run UM claim pays, which is why a "phantom vehicle" that runs you off the road without touching you is such a hard claim there. Our California guide covers what full coverage costs in the state where the question comes up most.
• Oklahoma sells UMPD as an optional add-on. If you carry liability only and skipped it, a hit-and-run on your parked car is an out-of-pocket repair.
• Texas folds property damage into UM/UIM, covers hit-and-runs, and sets the deductible at $250 by law.

The practical test: if you've dropped collision on an older car, ask your insurer one question. "If someone hits my parked car and drives away, what pays?" Our comprehensive vs. collision explainer covers the collision side of that answer; this coverage is the other side. And if the fleeing driver is later identified and turns out to be insured, your claim moves to their policy, and a repaired car's lost resale value becomes a diminished value claim against their insurer.

How much to carry

Three rules of thumb, in order of how often they're ignored:

1. Match your liability limits. If you carry 100/300 in liability, carry 100/300 in UM/UIM. You're insuring the same injuries; the only difference is who caused them. Insurers generally won't sell you more UM than you carry in liability anyway.
2. Don't let the state minimum set your number. In a 25/50 state, the mandated UM limit is $25,000 per person. An emergency room visit, a surgery and six weeks off work clear that quickly. The state minimum is the floor that keeps the policy legal, not the ceiling on what an uninsured driver can cost you; our state minimum coverage guide covers why those two numbers are so different.
3. If you're liability-only, buy UMPD where it exists. It's the closest thing to collision coverage for the specific case where the crash wasn't your fault, and in Texas it comes with a $250 deductible. TDI's rule of thumb is enough property damage coverage to replace your vehicle.

The coverage itself is relatively inexpensive compared with the other lines on a policy, per NerdWallet, though it costs more where more drivers are uninsured. On most policies it's the line that pays the most per dollar of premium in the one scenario your liability coverage can't touch.

What to do with this

1. Find the line on your declarations page. It's usually labeled UM/UIM with a limit like 25/50 or 100/300. If it's missing, you either live in a state that doesn't require it and declined it, or you signed a rejection in a state like Texas or Oklahoma.
2. Match it to your liability limit. The premium difference is small; the gap it closes is not.
3. If you've gone liability-only, ask what pays in a hit-and-run. In California the answer is nothing unless you carry collision; in Texas it's UM/UIM minus $250; in Oklahoma it's the UMPD add-on, if you bought it.
4. Price the whole policy, not the line. Compare quotes with UM/UIM matched to your liability limits for your ZIP code; the carriers that price liability cheapest in your state (our cheapest-companies ranking names them) often price this coverage very differently.
5. Re-check after a move. The rules in the table above change at the state line, and a policy written in a "not required" state doesn't automatically gain the coverage when you register in a "required" one. Our moving-states post covers the rest of what changes, and a fresh quote is the fastest way to see what your new state puts in the policy by default.

Coverage definitions and the required-states overview per the Insurance Information Institute ("Background on: Compulsory Auto/Uninsured Motorists," which also supplies the 2022 state-by-state uninsured shares from the Insurance Research Council and the note on stacking and on insurers being required to offer the coverage where it isn't mandatory); the "required" column reflects that report's financial-responsibility table, which excludes coverages a policyholder can reject, so a state shown as "not required" may still require insurers to offer it. National 2023 uninsured rate, with the Maine and Mississippi extremes, per the National Association of Insurance Commissioners' uninsured motorists topic page citing the Insurance Research Council. Texas rules (must offer, rejection in writing, $250 deductible, hit-and-run coverage, 12% of registered vehicles uninsured) per the Texas Department of Insurance ("Protect against other drivers with uninsured motorist coverage," March 2025) and the Texas Office of Public Insurance Counsel. Oklahoma per the Oklahoma Insurance Department as cited in our Oklahoma guide; Alabama, Arkansas, California, Florida, Georgia, Kentucky, Louisiana, Nevada, New Mexico and Pennsylvania per our state guides for those states. California's $3,500 UMPD cap, identified-driver condition and the physical-contact requirement for hit-and-run injury claims per California Insurance Code 11580.2 as summarized by CarInsurance.com and Bankrate. Cost characterization per NerdWallet. This is general information, not advice on your policy; your declarations page and your insurer govern.