What Is Uninsured / Underinsured Motorist Car Insurance?
Uninsured motorist (UM) and underinsured motorist (UIM) coverage protect you when the at-fault driver either has no auto insurance at all or does not carry enough insurance to pay for what they caused. NAIC frames UM directly: it "protects the policy holder directly" and "pays if you are injured by a hit-and-run driver or a driver who does not have auto insurance"1. Whether you have to carry UM or UIM, and in what form, is a state question, not a national one.
What it covers
Injuries and, in some states, property damage caused by an uninsured or underinsured at-fault driver
Legally required
Depends on the state; some require it, some require insurers to offer it, some leave it optional2
Includes hit-and-run
UM commonly applies when the at-fault driver is a hit-and-run1; treatment of hit-and-run property damage varies by state and policy
Whose loss?
Yours, when the other party has insufficient insurance to pay for it
What UM and UIM cover
UM and UIM are first-party coverages that step in when the at-fault driver's liability coverage cannot pay for the harm they caused. In practice they usually split into two parts: bodily injury and property damage. Whether one, the other, or both are available on your policy depends on your state23.
UM / UIM bodily injury
Pays for medical treatment, lost wages, and other bodily-injury damages you and your passengers suffer when the at-fault driver has no insurance or not enough bodily-injury liability to cover the harm. NAIC: uninsured motorists coverage "pays if you are injured by a hit-and-run driver or a driver who does not have auto insurance"1. UIM extends the same idea to a driver who has some coverage but not enough.
UM / UIM property damage
Pays for damage to your vehicle when the at-fault driver has no insurance or not enough property-damage liability. NAIC describes it as a coverage that responds to the same kind of loss collision does, but sourced from the other party's absence of coverage rather than a collision event3. Availability, deductibles, and whether hit-and-run property damage is included vary by state.
The specific wording of your declarations page and policy controls what UM and UIM actually pay for on your policy. Two states can describe UM slightly differently; two insurers can write the endorsement slightly differently. Treat the categories above as the standard shape, not a substitute for reading your policy.
What UM / UIM does not cover
- Damage or injuries you cause to others. That is what liability is for.
- Damage to your own vehicle from a covered collision where the at-fault driver has enough insurance. That is either their liability, or your own collision if you file first-party, depending on the state and the policy.
- Non-collision damage. Theft, weather, vandalism, animal strikes, glass, and similar losses are handled by comprehensive, not UM.
- Losses your policy specifically excludes. Named-driver exclusions, business-use exclusions, and other exclusions on a personal auto policy typically apply to UM/UIM the same way they apply to liability.
- Amounts above your UM / UIM limits. UM and UIM have their own per-person and per-accident limits on your policy, separate from your liability limits.
Uninsured vs. underinsured
The two coverages address different problems.
| Uninsured motorist (UM) | Underinsured motorist (UIM) | |
|---|---|---|
| Triggers when | The at-fault driver has no auto insurance, or is a hit-and-run who cannot be identified1 | The at-fault driver has liability insurance, but the limits are lower than the harm they caused |
| Typical parts | Bodily injury; property damage where the state and policy provide it | Bodily injury; some states offer UIM property damage, others do not |
| Legally required | Depends on the state2 | Depends on the state2 |
Some states package UM and UIM together on a single endorsement; other states let a consumer take one without the other, or reject either or both. The specific combinations available where you live are set by state statute, not by a national rule2.
Hit-and-run
Hit-and-run is the classic UM scenario for bodily injury. NAIC states directly that uninsured motorists coverage pays if you are injured by a hit-and-run driver1. Property damage from a hit-and-run is more variable: some states allow UM property damage on a hit-and-run subject to reporting requirements, and some send the same claim through collision coverage on your own policy. Reading the hit-and-run section of your policy alongside your state insurance department's guidance is the shortest path to the specific answer for your situation.
UM property damage vs. collision
Both UM property damage and collision can respond to physical damage to your own car; the question is which one picks up the claim. In most states, if the at-fault driver has property-damage liability that pays, that money handles your vehicle damage. If the at-fault driver has no insurance at all, UM property damage (where available in your state) is designed for that case. If the at-fault driver has some liability but not enough, UIM property damage may pick up the shortfall in states that offer it. Collision can respond regardless of fault, subject to your deductible. Which coverage actually pays depends on the state, the policy, whether the other driver is identified, and any subrogation the insurers do behind the scenes3.
How UM / UIM interacts with liability, PIP and MedPay
UM/UIM is a first-party coverage, so it lives on the same side of the policy as your other first-party protections.
- Liability. Liability pays other people when you are at fault. UM/UIM pays you when the other driver is at fault and cannot pay. The two coverages face opposite directions.
- PIP and MedPay. Personal Injury Protection and Medical Payments coverages pay medical expenses for you and your passengers regardless of fault, up to their own limits. UM bodily injury handles claims that go beyond what PIP or MedPay pays and are the fault of an uninsured or underinsured driver. In no-fault states, PIP typically handles first-dollar medical expenses and UM bodily injury steps in above the no-fault threshold when the at-fault driver is uninsured or underinsured. State-specific mechanics live in the state guides, not on this page.
- Collision. See the section above; the UM/collision overlap on vehicle damage is a state and policy question.
Is UM / UIM required in your state?
There is no single national answer. States generally take one of three approaches, and the same state may take different approaches to UM and UIM2.
- Required. The state requires UM and/or UIM on every personal auto policy.
- Required to be offered. The state requires insurers to offer UM and/or UIM at every renewal or new policy, and the consumer can reject the coverage in writing. Texas is an example of this approach: Texas insurers must offer both UM and UIM on every auto policy, and a driver who does not want the coverage must reject it in writing; if a written rejection is not on file, UM and UIM stay on the policy under Texas Insurance Code § 1952.1014. Other states have their own versions of this structure.
- Optional. Some states leave UM and UIM fully optional.
Because state statutes vary and change, this page does not attempt to list every state's current rule. See our state guides for the requirements where you live, or the Texas state guide for the worked example above.
Limits and deductibles
UM and UIM have their own per-person and per-accident limits on your policy, separate from your liability limits. Many insurers default the UM/UIM limits to match the liability limits you selected, but the state statute or your specific policy may allow a different structure. UM property damage often has its own deductible in states that offer it. Read the declarations page and the endorsement to see the actual numbers on your policy3.
YesWeSure Decision Check
Should you carry UM / UIM?
UM/UIM sits at the intersection of a state question (does your state require it, require it to be offered, or leave it optional) and a personal risk question (how comfortable are you being financially exposed to another driver's lack of insurance). Answer the state question first, then the personal one.
Question 1, the state rule: what does your state require?
- Look up the current rule. Use your state insurance department. The rule is a fixed answer for a given state and year, and it may treat UM and UIM differently.
- Confirm the format. Some states require the coverage outright; some require insurers to offer it (with a written rejection needed to remove it, as in Texas4); some leave it optional. Know which one applies to you before you decide.
- Treat this as a compliance answer, not a planning answer. A state minimum, or a required-offered structure, tells you the least the state will accept. It does not tell you what fits your situation.
Question 2, the personal risk decision: what level of UM / UIM fits your household?
- Consider the risk you are transferring. UM/UIM is protection against someone else's choices and someone else's coverage limits. The more drivers around you who carry only the state minimum or drive uninsured, the more UM/UIM does for you when they are at fault.
- Look at your household's financial exposure. Medical bills, lost wages, and vehicle-damage costs after a serious crash can exceed what many drivers carry. Only you know how much of that gap you are comfortable absorbing yourself.
- Compare limit levels concretely. Get quotes at more than one UM/UIM tier so the incremental cost of higher protection is a real number rather than a hypothetical.
- Think about how UM / UIM fits alongside your other coverages. Health insurance, PIP or MedPay, and collision each pay for parts of what UM/UIM addresses. UM/UIM is designed to cover what those coverages do not, when the at-fault party has too little insurance.
This is a reasoning framework, not personalized legal or financial advice. Your real answer depends on your state's rule, your quotes at different UM/UIM tiers, and how much financial risk you can absorb yourself.
Ready to see prices with different UM / UIM limits?
Compare car insurance quotesFiling a UM / UIM claim
UM and UIM claims are first-party claims on your own insurer, but the underlying facts (an at-fault driver who has no coverage or too little) usually mean the claim proceeds alongside investigations by your insurer and, if applicable, the at-fault driver's insurer. The general claim mechanics (reporting, adjuster, inspection, estimate, deductible, valuation, payment, disputes) are the same as any auto claim and live in our Guide: how to file a car insurance claim. For the immediate scene-and-aftermath view, which is a different question from the claim itself, see what to do after an accident.
Common questions
Is uninsured motorist coverage required?
It depends on your state. Some states require UM outright, some require insurers to offer it and let you reject it in writing, and some leave it fully optional2. Texas is an example of the require-offered structure: Texas insurers must offer both UM and UIM, and a driver who does not want the coverage must reject it in writing4. Check your state insurance department for the current rule where you live.
What is the difference between UM and UIM?
UM (uninsured motorist) applies when the at-fault driver has no auto insurance, or is a hit-and-run who cannot be identified1. UIM (underinsured motorist) applies when the at-fault driver has some liability coverage, but not enough to pay for the harm they caused. Some states package the two together; some let you take one without the other.
Does UM cover a hit-and-run?
UM bodily injury typically does. NAIC states that uninsured motorists coverage "pays if you are injured by a hit-and-run driver or a driver who does not have auto insurance"1. Hit-and-run property damage handling varies by state: some allow UM property damage subject to reporting requirements, some send the claim through collision. Read the hit-and-run section of your policy for the specifics.
Do I need UM if I have health insurance?
UM bodily injury and health insurance can both respond to injuries after a crash, but they are not interchangeable. Health insurance handles medical treatment under its own network, copay, and deductible rules. UM bodily injury covers a wider set of damages, including things like lost wages and pain-and-suffering, that health insurance does not pay. Whether that difference matters to you is part of the Decision Check above.
How does UM property damage differ from collision?
Collision responds to damage to your own vehicle from a covered collision regardless of fault, subject to your deductible. UM property damage, in states that offer it, responds specifically when the at-fault driver has no insurance. In many cases the same event could be filed under either coverage, and which one pays depends on the state, the policy, and any subrogation the insurers do afterward.
Can I reject UM / UIM?
In some states, yes. In require-offered states such as Texas, a driver who does not want UM/UIM must reject it in writing, and if a written rejection is not on file the coverage stays on the policy4. In states that require UM/UIM outright, rejection is not available. In fully optional states, the coverage is offered as an add-on.
How much UM / UIM should I carry?
Work through the Decision Check above. Look at the state rule that applies, then weigh the risk you are transferring (someone else's lack of insurance) against the incremental cost of higher limits. Do not use a fixed rule like "match your liability limits" without checking that it makes sense for your household; your specific numbers matter.
Will filing a UM / UIM claim raise my rate?
It depends on the insurer, the state, and the claim. UM/UIM claims are first-party claims on your own insurer, but insurer rating treatment varies. There is no universal answer, so ask your insurer how they handle UM/UIM claims in your state before you file.
Sources & methodology
- NAIC: Auto Insurance consumer guidance (National Association of Insurance Commissioners)
- NAIC: Uninsured Motorists (insurance topic overview) (National Association of Insurance Commissioners)
- NAIC: What Does Auto Insurance Cover? (National Association of Insurance Commissioners)
- Texas Insurance Code § 1952.101: Uninsured / Underinsured Motorist Coverage; Rejection (Texas Legislature (Statutes))
The definition of uninsured motorists coverage and the explicit hit-and-run bodily-injury framing are quoted from NAIC consumer guidance. The three-way structure (required, required-offered, optional) reflects NAIC's uninsured-motorists topic overview and is cross-checked against the Texas Insurance Code § 1952.101 worked example, which requires Texas insurers to offer both UM and UIM and requires a written rejection to remove them. This page does not publish a 50-state table and does not claim UM/UIM is required nationally. Where the exact rule matters, the state department of insurance is where the current rule is published. This page publishes no dollar figures. Last reviewed .