Uninsured Motorist Coverage Explained

Do you need uninsured motorist coverage?

If another driver hurts you and has no insurance, the law does not make that driver pay you. A court can order it, but someone with no insurance often has no money either. Uninsured motorist coverage, or UM, is your own policy stepping in. It pays your medical bills and other losses up to the limit you chose.

Most drivers should keep it. The cost of skipping it shows up on the worst day. A serious injury can run into six figures, and the state minimum limits on many policies are far lower than that.

Whether you can say no depends on where you live. In some states UM comes with every policy. In others it is offered, and you decline in writing. This guide explains what UM and its cousin, underinsured motorist coverage (UIM), actually pay. It covers hit-and-run crashes, the stacking option, and how to pick limits. It also shows how the same crash can pay out differently in two states.

What does uninsured motorist coverage pay for?

UM covers your injuries when the driver at fault has no liability insurance, or drives away and is never found. UIM covers the gap when the other driver has some insurance, but not enough to pay what you lost.

Typical UM and UIM claims include:

• Medical bills, including hospital stays, therapy and future care
• Lost wages while you recover
• Pain and suffering, depending on your state (Florida limits it to serious injuries)
• Funeral costs, if the crash is fatal

It usually covers more people than you. In California, for example, the law names you, your spouse, relatives living with you and anyone riding in your insured car. You are covered as a driver, a passenger, or on foot or on a bike. Check your own policy for the exact list.

Property damage works differently. Texas says UM and UIM can pay for repairs to your car, with a deductible. Illinois sells UM property damage as an optional extra, and it pays only when the at-fault driver is identified. If the other driver is unknown, your own collision coverage is usually the only route.

How many drivers are uninsured?

More than you might guess, and the number has been rising. The Insurance Research Council (IRC), an insurer-funded research group, estimated that 15.4% of drivers were uninsured in 2023. That was up from 11.6% in 2019. Counting drivers with too little coverage, about one in three was either uninsured or underinsured.

The IRC does not count cars. It compares injury claims from uninsured drivers with claims from insured ones. So it is an estimate, not a headcount.

The range by state is wide. Mississippi had the highest rate at 28.2%, followed by New Mexico and the District of Columbia. Maine had the lowest at 5.7%, then Utah and Idaho.

Here is a pattern we found by lining up the IRC list with each state’s rules. Of the ten states with the most uninsured drivers, eight let you decline UM or treat it as optional: Mississippi, New Mexico, Michigan, Tennessee, Florida, California, Colorado and Washington. Only D.C. and Missouri build it into every policy. The places where you are most likely to meet an uninsured driver are mostly the places where you can say no to the protection.

The IRC’s latest report covers 2023. We found no newer national figure, so treat these numbers as a snapshot.

Is uninsured motorist coverage required in your state?

It depends on the state, and the sources count differently. Triple-I says about 20 states and D.C. require UM or UIM. Our review of state laws and regulator pages found a similar total, with a few states in a gray area. The table groups states by what the rules say. It is a guide, not a substitute for your policy or your state regulator.

A few notes on this table. New York’s mandatory UM is a basic layer. The state also sells an optional upgrade called supplementary UM/UIM, which you can buy up to your liability limits and a legal cap of $250,000 per person. North Carolina raised its minimum liability limits in 2025, and UM follows them. Michigan’s status comes from the state insurance department’s consumer guide, which lists UM and UIM as optional; we did not check the statute.

Also check how “decline” works. Texas, Florida and others require a signed form. If you signed one years ago and forgot, you may have no UM today. Many states do not require the insurer to add it back at renewal unless you ask in writing.

What is the difference between underinsured and uninsured coverage?

Uninsured means the at-fault driver has no policy, or flees. Underinsured means that driver has a policy, but it is too small. Many states sell them together as one coverage, and in California any policy that has UM must also include UIM.

The tricky part is how “too small” is measured. States use two main methods, and the difference can cost you real money.

Method 1: your damages versus their limit. Florida treats a driver as underinsured when their limits are less than your total damages. The at-fault driver’s insurer pays first. Your UM then covers the rest, up to your own limit. Your UM limit is not reduced by what the other driver paid.

Method 2: your limit versus their limit. California treats a driver as underinsured only when their limits are lower than the UM limit you carry. Your insurer then pays up to your limit minus whatever the other driver’s insurance paid. Ohio’s law, as recorded in our state data, works in a similar way.

Here is an example with invented numbers. You are badly hurt, and a jury would value your losses at $150,000. The other driver has a $25,000 liability limit. You carry $100,000 of UIM.

• Damages method (Florida): the other driver’s insurer pays $25,000, and your UIM pays up to $100,000 for the rest. You can recover $125,000.
• Limit-to-limit method (California): your UIM pays at most your $100,000 limit minus the $25,000 already paid. You recover $100,000.

Same crash, same limits, $25,000 apart. Your own policy wording can change the result, so ask your insurer which method applies to you.

What is stacking, and can you get it?

Stacking adds up your UM or UIM limits across more than one car or policy. With two cars that each carry $50,000, stacking could give you up to $100,000 for one injury. It applies to injuries only. It never raises what your policy pays to fix your car.

Whether you can stack depends on the state, and even consumer guides get it wrong at times.

• Florida makes stacking the default. Insurers may also offer a cheaper unstacked version, with a premium at least 20% lower, if you sign a form accepting it.
• California bans it. The law says limits for two or more vehicles or policies may not be added together.
• Pennsylvania also stacks by default. Its Insurance Department says stacked coverage applies unless you reject it, and that rejecting it lowers your premium. MoneyGeek, a consumer site, says the state bans stacking, but its own state table shows stacking allowed.

MoneyGeek’s 2026 list names 18 states that do not allow stacking, and Pennsylvania is not one of them. Treat any list as a starting point. Even where stacking is legal, an insurer may not offer it.

Stacking costs more. It helps most if you have several cars on one policy, a modest limit on each, and a serious injury that would exceed one car’s limit. If you own one car, there is nothing to stack.

Does uninsured motorist coverage pay in a hit-and-run?

Usually yes, for injuries. But hit-and-run claims come with strict conditions, and missing one can sink the claim.

• Texas: the Texas Department of Insurance warns that UM will not pay a hit-and-run claim you did not report to police. Our state data shows the law also requires actual physical contact with the unknown driver’s vehicle.
• California: the law requires physical contact, a police report within 24 hours, and a sworn statement to your insurer within 30 days. Miss the 24 hours and the claim can fail.
• Ohio: an unidentified driver counts only with independent corroboration of what happened.

Contact rules matter in “phantom vehicle” crashes. A car cuts you off and you swerve into a wall. The other car never touched you. In states with a contact rule, that crash may not qualify.

Call the police from the scene, get any witness names, and photograph the road. Tell your insurer the same day.

How much uninsured motorist coverage should you buy?

Start with your liability limits. Many states set UM at that level unless you ask for less. The reasoning is simple. Your liability limits are how much you think you need to protect others. UM is the same protection for you.

Then adjust with a few questions:

1. Could you pay a large bill yourself? If not, go higher, not lower.
2. How is your health insurance? A high deductible means UM has more gaps to fill.
3. Who rides with you? Passengers’ injuries may fall under your UM.
4. Does your state have many uninsured drivers? Rates above 20% are common in several states, so the odds are not remote.
5. Do you have several cars? If your state allows stacking, price it.

Price matters too, but we do not give figures here. The price of UM varies from state to state, and stacking raises it. Ask for quotes at your liability limits, at the state minimum and one step higher. Seeing all three on the same page makes the decision easier. Our guide to reading a car insurance quote shows where to find them.

Common mistakes

• Rejecting UM to save a few dollars. The savings can be small compared with what one uncovered injury costs.
• Forgetting an old rejection form. Signing one once can carry over to renewals.
• Assuming UM fixes your car. In many states it covers injuries only. Collision does the car, as our guide on full coverage versus liability-only explains.
• Skipping the police report. Hit-and-run claims often depend on it.
• Settling with the other driver’s insurer too fast. In some states, settling without your own insurer’s consent can hurt a UIM claim. Florida gives your insurer 30 days to respond to a proposed settlement. Ask before you sign a release.

What to do next

1. Find your declarations page, the first page of your policy, and look for “uninsured” and “underinsured” lines and the limit beside each.
2. Compare that limit with your liability limit. If it is lower, ask what it would cost to match.
3. Ask your insurer in writing whether you ever signed a rejection or lower-limit form.
4. Ask whether stacking is available, what it costs, and how your policy handles underinsured claims.
5. Check your state’s rule using the table above or our state minimum lookup. For state pages, see Texas, Florida and Mississippi.
6. If a crash happens, call the police, write down witness names, and report it to your insurer the same day.

Bottom line

If a driver without enough insurance hurt you tomorrow, UM and UIM would be what pays. If you live where you can decline it, think hard before you do, especially in a state with many uninsured drivers. If you choose, a sensible default is limits equal to your liability limits. Confirm your state’s rules for stacking and hit-and-run claims with your insurer or state insurance department. This guide is general information, not legal or financial advice.