What is uninsured/underinsured motorist coverage?

It's the coverage that pays for your injuries, and in some states your car, when the at-fault driver has no insurance (uninsured) or too little to cover your losses (underinsured). It steps into the gap the other driver's policy should have filled but couldn't.

Is uninsured motorist coverage worth it?

For most drivers, yes. About one in seven US motorists is uninsured, and a much larger share carries only the state-minimum limits that a serious injury blows through in minutes. UM/UIM is usually inexpensive relative to how much it protects, because it's the only coverage that fills the hole a broke or underinsured driver leaves.

What's the difference between uninsured and underinsured motorist coverage?

Uninsured motorist (UM) covers you when the at-fault driver has no insurance at all. Underinsured motorist (UIM) covers you when they have insurance, but their limit is lower than your losses. They're usually sold together as UM/UIM and both address the same problem: the other driver can't pay for the harm they caused.

Does uninsured motorist coverage cover hit-and-run?

In most states, yes: a hit-and-run driver is treated as uninsured because they can't be identified to pay. Uninsured motorist bodily injury typically responds to hit-and-run injuries. Whether it covers hit-and-run damage to your car depends on your state and whether you carry uninsured motorist property damage.

Do you need uninsured/underinsured motorist coverage?

Roughly one in seven US drivers has no insurance, and many more carry the bare state minimum. Uninsured/underinsured motorist coverage is the piece that protects you when they hit you. Here's how it works and who needs it.

In short

Uninsured/underinsured motorist coverage (UM/UIM) pays for your injuries when the at-fault driver has no insurance or not enough to cover what they did to you. With roughly one in seven US drivers uninsured, and many more carrying only the state minimum, it's the coverage that keeps someone else's bad decision from becoming your medical bill. It's usually cheap for the protection it buys, and in some states it's required. For most drivers it's worth carrying, ideally at limits matching your own liability. Size your coverage to see where it fits.

Liability insurance is built around a simple assumption: when someone causes a crash, their policy pays for the damage. Uninsured/underinsured motorist coverage exists because that assumption fails constantly. Some drivers carry nothing. Many carry the legal minimum, which a single ambulance ride and ER visit can exhaust. UM/UIM is the coverage that protects you from their gap.

What UM/UIM actually covers

There are two related pieces, usually sold together:

Uninsured motorist (UM) responds when the at-fault driver has no insurance at all, including, in most states, a hit-and-run driver who can't be identified.
Underinsured motorist (UIM) responds when the at-fault driver has insurance, but not enough: their limit runs out before your losses do, and UIM covers the difference up to your own limit.

Both primarily cover bodily injury: your medical bills, lost wages, and related costs when someone else hurts you and can't pay. Some states also offer uninsured motorist property damage, which can cover damage to your car from an uninsured driver.

UM/UIM protects you and usually your passengers and household family members, often even when you're a pedestrian or cyclist struck by an uninsured driver, not just when you're in your own car. Check your policy, but the protection frequently follows the person, not only the vehicle.

Why it matters more than people think

The case for UM/UIM comes down to two numbers. First, the uninsured rate: nationally about 14% of drivers carry no insurance, and in some states it's over a quarter. Second, the minimum-limits problem: even insured drivers often carry the lowest limits their state allows, figures like $25,000 per person that vanish against a serious injury.

Put those together and a large share of the cars around you can't actually pay for the harm they might cause. Your own liability coverage does nothing here: it pays other people when you're at fault. UM/UIM is the only coverage pointed at the reverse problem.

How much to carry

A clean rule: match your UM/UIM limits to your own liability limits. If you've decided your assets and income justify, say, 100/300 in bodily-injury liability, your own body is worth protecting to the same degree. Carrying high liability but minimal UM/UIM protects strangers better than it protects you.

If you have health insurance, some of your medical costs may be covered regardless, but health insurance doesn't replace lost wages, and it may seek reimbursement from any settlement.
In no-fault states, personal injury protection (PIP) covers some medical costs first, with UM/UIM layering on top for serious injuries that break through no-fault thresholds.

When it's required, and when you can skip it

Several states require UM (and sometimes UIM); others require insurers to offer it and let you reject it in writing. Rejecting it to save a small premium is usually a poor trade, because it removes your protection against the exact drivers most likely to hurt you and disappear.

The narrow case for carrying less: if you have robust health insurance, strong disability coverage, and no dependents relying on your income, the injury-replacement role of UM/UIM is partly filled elsewhere. Even then, the coverage is typically cheap enough that keeping it is the easy call.

Key takeaways

UM/UIM pays for YOUR injuries when the at-fault driver has no insurance or too little.
About one in seven US drivers is uninsured, and many more carry only the state minimum.
Uninsured motorist also usually covers hit-and-run injuries.
Match your UM/UIM limits to your own liability limits: protect yourself as well as strangers.
Some states require it; rejecting it to save a little is rarely worth the exposure.

The bottom line

Liability insurance assumes the other driver can pay. UM/UIM is what you carry because, far too often, they can't. It's inexpensive relative to what it protects, it covers hit-and-run, and it points at the one risk your own liability policy ignores entirely, the person who hits you and has nothing. For most drivers, keep it, and set the limits to match how much you'd protect anyone else.

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Size your liability, then set UM/UIM to match, so a broke driver's mistake doesn't become your bill. Free, no email, open source.