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Uninsured and underinsured motorist coverage explained
How UM and UIM coverage pay when the driver who hits you has no insurance or too little, which states require it, and how much to buy.
Uninsured motorist (UM) coverage pays for your injuries when a driver who is legally at fault has no liability insurance, or when a hit-and-run driver cannot be found. Underinsured motorist (UIM) coverage pays when the at-fault driver has insurance but not enough to cover your losses. You buy both on your own policy, and they protect you, your household and your passengers.
The risk is not small. The Insurance Research Council estimated in February 2025 that 15.4 percent of U.S. drivers were uninsured in 2023, more than one in seven, and that 33.4 percent were either uninsured or carrying too little coverage. State rates ranged from 5.7 percent in Maine to 28.2 percent in Mississippi. See uninsured drivers by state for more.
The three parts: UM, UIM and UMPD
- Uninsured motorist bodily injury pays what you could have recovered from an uninsured at-fault driver for injuries: medical bills, lost income, and pain and suffering, up to your limit. It usually also applies to hit-and-run accidents.
- Underinsured motorist bodily injury applies when the at-fault driver's bodily injury liability limits are too low. In some states UM and UIM are sold as one combined coverage.
- Uninsured motorist property damage (UMPD) pays for damage to your car caused by an uninsured driver. It is not available in every state, often has a deductible, and can overlap with collision coverage.
UM and UIM are limits you choose, written like liability limits. "100/300" means up to $100,000 per injured person and $300,000 per accident.
Which states require it
According to the Insurance Information Institute's state table (compiled from American Property Casualty Insurers Association data), uninsured motorist coverage is compulsory in Connecticut, the District of Columbia, Illinois, Maine, Maryland, Minnesota, Missouri, Nebraska, New Jersey, New York, North Carolina, North Dakota, Oregon, South Carolina, South Dakota, Vermont, Virginia, West Virginia and Wisconsin. The statutes also make it mandatory in Kansas (K.S.A. 40-284, which also requires UIM and lets you reject only limits above the state minimum) and Massachusetts (M.G.L. c. 175, § 113L). Several of these states also require UIM.
In most other states, insurers must offer UM and you must reject it in writing if you do not want it. Florida law, for example, applies UM to every policy unless a named insured signs a written rejection (Fla. Stat. 627.727). New Hampshire is a special case: insurance is optional for most drivers there, but any auto liability policy you buy must include UM equal to your liability limits (RSA 264:15). If you signed a rejection years ago, it usually stays in force at every renewal until you ask to add the coverage back.
Rules change and the required limits differ, so check your own state in the state car insurance requirements lookup.
How UIM fills the gap: an example
Say another driver runs a red light and you suffer $120,000 in medical bills, lost wages and other damages (a hypothetical figure). The other driver carries 25/50 liability, so their insurer pays its $25,000 per-person limit. You carry 100/300 UIM.
What happens next depends on how your state and policy define UIM:
| UIM approach | How it works | What your UIM pays here |
|---|---|---|
| Excess ("damages exceed") | UIM pays damages above what the at-fault driver's insurer paid, up to your UIM limit | Up to $95,000 |
| Offset ("limits less than") | UIM applies only if their limit is lower than yours, and their payment is subtracted from your limit | $100,000 − $25,000 = $75,000 |
Either way, UIM is what turns a $25,000 recovery into something close to your real losses. Without it, you would be left suing an individual who may have no assets.
UMPD and your car
UMPD is narrower than people expect, and states set it up differently. Two examples:
- South Carolina requires UM on every policy, including at least $25,000 of property damage coverage, and allows the policy to exclude the first $200 of the loss (S.C. Code § 38-77-150).
- California limits UMPD for cars without collision coverage to the lesser of actual cash value or $3,500. If you carry collision, insurers must offer a version that pays your collision deductible when an uninsured driver hits you, provided there was physical contact, the driver or license plate is identified and you report within 10 business days (Cal. Ins. Code § 11580.26).
If you already have collision coverage, UMPD's main value is often avoiding or reducing your collision deductible. If you do not have collision, UMPD may be the only way your car gets fixed after an uninsured driver hits it. See do you pay a deductible if the accident was not your fault?.
Hit-and-run accidents
UM bodily injury generally treats a hit-and-run driver as uninsured, but policies and states attach conditions: prompt police reports, physical contact in some cases, and notice to your insurer within a short period. Property damage from a hit-and-run is often handled under collision instead of UMPD, especially where UMPD requires the other driver to be identified. See hit-and-run accidents: how to file a claim.
How much UM and UIM to buy
The conventional advice is to match your UM/UIM limits to your own liability limits. The logic: you have decided your liability limits are what you need to protect others, and your own family's injuries are worth at least as much. Use the How much car insurance do I need? to test different levels.
Factors that point toward higher limits:
- Thin health coverage. A high-deductible plan, no disability insurance or no sick leave leaves more of an injury's cost on you.
- A high uninsured rate in your state.
- Passengers you carry regularly, including children and carpool riders.
- Lots of time on foot or bike. UM often covers you as a pedestrian or cyclist hit by an uninsured car.
UM/UIM is usually a modest part of the premium compared with liability. If you own several cars, ask about stacking, which can multiply your limits in states that allow it.
Filing a UM or UIM claim
A UM claim is made against your own insurer, but it does not feel like an ordinary first-party claim. Your insurer stands in the shoes of the at-fault driver and can argue about fault and the value of your injuries, just as the other driver's insurer would.
- Report the accident to police, and to your insurer as soon as you can.
- Get the other driver's insurance details, or confirm in writing that they have none.
- Tell your insurer before settling with the at-fault driver's insurer. Many policies require notice or consent before you accept a liability settlement, and settling without it can jeopardize UIM benefits. Some states restrict these clauses; South Carolina, for example, bars consent-to-settle clauses in UIM coverage.
- Document everything: medical records, wage loss, and out-of-pocket costs.
- Consider legal advice for serious injuries, since UM and UIM disputes often go to arbitration or court. See what to do after an accident with an uninsured driver.
Key takeaways
- UM pays for your injuries when the at-fault driver has no insurance or flees; UIM pays when their limits are too low.
- About 20 states plus D.C. require UM; elsewhere insurers must offer it and you must reject it in writing.
- UMPD for car damage varies widely by state and often overlaps with collision coverage.
- Matching UM/UIM limits to your liability limits is the standard starting point.
- Notify your own insurer before accepting any settlement from the at-fault driver's insurer.