Uninsured and Underinsured Motorist Coverage Explained: 1 in 7 Drivers, State Rules and Cost

Last Updated on October 25, 2026 by Syed Sarim Naqvi

Uninsured and underinsured motorist (UM/UIM) coverage pays your injuries, and in some states your car damage, when an at-fault driver has no insurance or too little, and the Insurance Research Council estimated 14.0% of US drivers were uninsured in 2022. The catch is that cost and rules vary: sources put it at about $20 to $50 a year as a bundle to $111 a year for UM bodily injury, and 20 or 21 states plus Washington, D.C. require some form of it, with some allowing you to reject it in writing.

Key Takeaways

The IRC estimated 14.0% of drivers, about one in seven, were uninsured in 2022, up from 11.1% in 2019, and a 2025 IRC study cited by MoneyGeek puts the 2023 rate at 15.4%
The highest 2022 rates were in D.C. (25.2%), New Mexico (24.9%) and Mississippi (22.2%); the lowest were Wyoming (5.9%) and Maine (6.2%)
UM applies when the at-fault driver has no insurance or is a hit-and-run, while UIM applies when their limits are too low for your losses
Costs reported range from $20 to $50 a year bundled (FinHabits) to $111 a year for UM bodily injury (CarInsurance.com) and about $78 per insured vehicle in IRC 2016 data
Insurance Information Institute-based counts say 20 states and D.C. mandate UM or UIM, while Bankrate cites 21 states and D.C., and some let you reject it in writing

What Is Uninsured Motorist Coverage?

The IRC describes UM as the part of an auto policy that protects an insured driver from expenses such as medical bills and lost wages caused by an at-fault uninsured or hit-and-run driver. An insurance-regulator fact sheet adds that UM and UIM reimburse policyholders in an accident involving an uninsured, underinsured or hit-and-run driver. MoneyGeek notes UM covers injuries and, in some states, vehicle damage, and that UIM covers the gap when an at-fault driver carries liability insurance that does not fully pay for the harm.

What Is the Difference Between UM and UIM?

FinHabits says UM/UIM protects you when the at-fault driver carries no insurance or too little of it, and shows how stacking works: two cars with $50,000 of UM each can give a $100,000 effective limit per claim. Bankrate says very few states require uninsured or underinsured property damage cover, which may still be worth adding. MoneyGeek calls underinsured drivers the bigger half of the problem, since many high-UM states also have high UIM rates.

Situation	Coverage That Responds	Key Catch
At-fault driver has no insurance	Uninsured motorist (UM)	May cover injuries only; property damage varies by state
Hit-and-run driver	UM, per the IRC	Reporting requirements apply in most policies
At-fault driver has low limits	Underinsured motorist (UIM)	Pays the gap above their limit, up to your limit
Multiple vehicles on your policy	Stacking, where allowed	Can raise the effective limit

How Common Are Uninsured Drivers?

The IRC release says the share was 11.1% in 2019, 13.9% in 2020, 14.2% in 2021 and 14.0% in 2022, based on claim data from 10 major insurers representing about 56% of the private passenger auto market. In 2022 the IRC counted 19 states plus D.C. above the national rate and 31 below. MoneyGeek cites the IRC’s 2025 study of 2017 to 2023 data at 15.4%, so the trend since 2022 appears to be upward.

How Much Does It Cost?

CarInsurance.com says UM bodily injury coverage averages $111 a year. FinHabits says adding UM/UIM typically costs $20 to $50 a year, roughly $2 to $4 a month, while Bankrate says $5 to $25 a month depending on your driving profile and insurer, and cites the IRC’s roughly $78 per insured vehicle from 2016. The sources disagree because they use different years, limits and states. As an illustration, not a quote, $111 a year is about $9 a month, a small fraction of a serious injury bill.

Which States Require It?

The insurance-regulator fact sheet, drawing on state insurance departments and APCIA, says 20 states and D.C. have mandatory UM or UIM requirements. Bankrate says 21 states and D.C. mandate UM, though some let you reject it in writing, and another Bankrate page notes many states require it as part of minimum cover. FinHabits lists 14 states plus D.C. as requiring UM, so counts differ by definition and date. Check your state’s rules, including whether you must reject in writing.

What Should You Check Before Buying?

Limits: match UM/UIM limits to your own liability limits where you can
Stacking: ask whether your state and insurer allow it
Property damage: check whether UM property damage is offered
Rejection form: do not sign it without understanding what you give up
Other cover: health insurance does not replace UM for lost wages

How Does This Connect to Other Auto Cover?

Motorcycle riders face this risk in Motorcycle Insurance Explained, and ATV owners in ATV and UTV Insurance Explained. Lost car value is in Diminished Value Claims Explained, loan gaps in Gap Insurance Explained, and added liability in Umbrella Insurance Explained.

FAQ

What does uninsured motorist coverage pay?

Your injuries and, in some states, vehicle damage when the at-fault driver has no insurance.

What is underinsured motorist coverage?

Cover for the gap when the at-fault driver’s limits are too low.

How many drivers are uninsured?

About 14.0% in 2022 per the IRC, and 15.4% for 2023 in a later study.

Is UM required?

In about 20 or 21 states plus D.C., depending on the source, and some allow rejection in writing.

How much does it cost?

Sources range from $20 to $50 a year bundled to $111 a year for UM bodily injury.

What is stacking?

Combining limits across vehicles, for example $50,000 on two cars for $100,000.

Which states have the most uninsured drivers?

D.C., New Mexico and Mississippi in 2022.

Glossary

UM: uninsured motorist coverage.
UIM: underinsured motorist coverage.
Stacking: combining UM limits across vehicles or policies.
Hit-and-run: an at-fault driver who leaves without being identified.
IRC: Insurance Research Council, an industry research body.

Sources

Insurance Research Council: 14 Percent of U.S. Drivers Were Uninsured in 2022 (14.0%, state rates, UM definition)
MoneyGeek: Uninsured Motorist Statistics (2026 Update) (15.4%, UIM, 20 states plus D.C.)
CarInsurance.com: Uninsured Motorist Coverage and State Averages ($111 average, rate history)
Bankrate: Uninsured Motorist Statistics (21 states plus D.C., $78 per vehicle)
Bankrate: Uninsured Motorist Coverage ($5 to $25 a month, property damage)
FinHabits: Uninsured and Underinsured Motorist Coverage ($20 to $50 a year, stacking example)
Insurance Information Institute: Facts and Statistics, Uninsured Motorists (20 states plus D.C., state minimums)

Published October 2026. Rates, state rules and plan terms vary and change often; always read your UM/UIM limits, stacking rules and any rejection form, and refresh this article periodically. State counts differ by source and date.

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