Uninsured motorist coverage

How UM and UIM coverage protect you when the at-fault driver has no insurance or not enough, and why roughly one in seven drivers makes it worth a look.

Auto insurance is built on a handshake: if someone causes a crash, their liability coverage pays for the damage. Uninsured motorist coverage exists for the moments that handshake fails, when the at-fault driver has no insurance at all, or not enough to cover what happened.

Why this coverage exists

Driving without insurance is illegal almost everywhere, but it still happens a lot. The Insurance Research Council estimates that about one in seven U.S. drivers (15.4% in 2023) had no insurance, and when you add drivers whose limits are too low to cover a serious crash, roughly one in three drivers is either uninsured or underinsured.

So this isn't coverage for a rare fluke. It's coverage for a fairly ordinary risk: the careful driver who does everything right and still gets hit by someone who can't pay.

The pieces, in plain words

Uninsured motorist coverage usually comes in a few variants, and not every state offers all of them:

Uninsured motorist bodily injury (UMBI) pays medical bills, lost wages, and related costs for you and your passengers when the at-fault driver has no insurance. It typically covers hit-and-run crashes too, since a driver you can't identify can't pay.
Uninsured motorist property damage (UMPD) pays for damage to your car in the same situation, where it's offered. If you carry collision coverage, that can fill this role instead.
Underinsured motorist coverage (UIM) handles the in-between case: the other driver has insurance, but their limits run out before your bills do. Your UIM coverage picks up from there, up to your own limits.

In some states UM and UIM are bundled together; in others they're separate line items. Your quote will spell out which is which.

What it feels like in practice

Say you're rear-ended at a light and end up with $30,000 in medical bills. If the other driver carries only a low bodily injury limit, their policy pays up to that limit and then stops. Without UIM, collecting the rest would mean suing someone who, statistically, may not have much to collect. With UIM, your own insurer covers the gap up to your limit, and you deal with one company instead of chasing a stranger.

Is it required?

In some states, yes. A number of states require uninsured motorist coverage, and some require insurers to include it unless you reject it in writing. Elsewhere it's fully optional. Rather than list every rule here, our state requirements guide covers what applies where you live.

Choosing your limits

A common approach is to match your UM/UIM limits to your liability limits. The logic is simple: if that's the level of protection you think other people deserve when you cause a crash, it's reasonable to give yourself the same. UM/UIM coverage is often one of the less expensive parts of a policy relative to what it protects, so raising it rarely moves your premium dramatically.

If you already have a policy, it's worth a two-minute look at your declarations page to see whether UM/UIM is on it and at what limits. Plenty of drivers discover they've been carrying the bare minimum without ever choosing it.