Uninsured Motorist Coverage Explained

Uninsured motorist (UM) coverage pays your medical bills, lost wages, and related costs when you’re hit by a driver with no insurance — or in a hit-and-run. Underinsured motorist (UIM) coverage steps in when the at-fault driver’s liability limits are too low to cover your losses. With more than one in seven US drivers uninsured in 2023, this is one of the most underappreciated coverages on a policy.

What UM/UIM actually pays for

	UM (uninsured)	UIM (underinsured)
Trigger	At-fault driver has no insurance, or flees the scene	At-fault driver’s liability limits don’t cover your losses
Pays	Your medical bills, lost wages, pain and suffering (up to limits)	The gap between their limits and your actual losses
Property damage	UM property-damage coverage available in some states	Usually bodily injury focused
Deductible	Typically none for UM bodily injury	Typically none

The Insurance Information Institute describes UM/UIM as coverage that “reimburses policyholders in an accident involving an uninsured, underinsured or hit-and-run driver.” Note the NAIC’s practical warning: most insurers won’t let you buy UM/UIM limits higher than your liability limits — so if you want strong UM protection, you need strong liability limits first.

How many drivers are uninsured

According to the Insurance Research Council’s 2025 study, reported by the Insurance Information Institute:

• 15.4% of US drivers were uninsured in 2023 — more than one in seven, and up from 11.6% in 2019.
• The uninsured rate has risen most years since 2019; the pandemic years saw the sharpest jump.
• The worst states: Mississippi (28.2%), New Mexico (24.1%), and the District of Columbia (23.1%).
• The best states: Maine (5.7%), Utah (6.2%), and Idaho (6.4%).

A separate IRC finding: 15.7% of drivers were underinsured in 2022 — carrying liability limits too low to cover the damage they cause. Add the two together and roughly three in ten drivers on the road either have no insurance or not enough of it. That’s the pool UM/UIM protects you from.

Which states require it

Twenty states and the District of Columbia mandate uninsured or underinsured motorist coverage, per the Insurance Information Institute. States with UM/UIM requirements include Connecticut, Illinois, Maine, Maryland, Minnesota, Nebraska, New Jersey, New York, North Carolina, North Dakota, Oregon, South Carolina, South Dakota, Vermont, Virginia, West Virginia, and Wisconsin, among others — always confirm current rules with your state’s insurance department, since legislatures update these lists.

Even where it’s optional, insurers in many states must offer it and require you to reject it in writing. The NAIC’s quote-comparison guide lists UM/UIM among the coverages that should match quote-to-quote when shopping. Think carefully before signing that rejection: UM/UIM is typically one of the cheapest coverages on the policy relative to what it pays out.

Note that requirements differ between bodily-injury UM/UIM and property-damage UM — some states require one but not the other. And in no-fault states, the interaction with personal injury protection adds another layer worth understanding.

Why it matters more than it looks

Consider a realistic scenario: you’re stopped at a light and rear-ended by an uninsured driver. You need surgery and miss two months of work. The other driver has no insurance and no assets worth pursuing. Without UM coverage:

• Your health insurance covers medical bills (minus deductibles and copays), but not lost wages.
• Your collision coverage (if you carry it) repairs your car — see collision vs. comprehensive.
• Nobody pays your lost income or the gaps in your medical bills.

With UM coverage, your own policy steps into the shoes of the at-fault driver’s missing liability insurance and pays those losses up to your UM limits. It’s the coverage that protects you from other people’s irresponsibility — the mirror image of liability, which protects others from yours.

The trend makes it more urgent, not less: with the uninsured rate climbing from 11.6% (2019) to 15.4% (2023), the odds of meeting an uninsured driver have risen by roughly a third in four years.

How much UM/UIM to carry

Drivers in this situation commonly consider:

• Matching your liability limits. Since most insurers cap UM/UIM at your liability limits anyway, carrying 100/300 UM/UIM alongside 100/300 liability is the natural pairing. Minimum UM limits (like 25/50) can be exhausted by a single emergency-room visit.
• Stacking, where allowed. Some states permit “stacking” UM coverage across multiple vehicles on a policy, multiplying your effective limits. Ask your agent whether your state allows it — it’s often cheap.
• Adding UM property damage if your state offers it and you don’t carry collision. It covers your car’s damage from an uninsured driver, usually with a small deductible.
• Not rejecting it to save a few dollars a month. UM/UIM is consistently among the least expensive line items on a declarations page. The full coverage vs. liability decision framework treats it as core protection, not an add-on.

After any crash with an uninsured driver, documentation matters enormously — see what to do after a car accident and how to file a car insurance claim.

UM/UIM vs. health insurance vs. PIP: who pays what

Drivers often ask why they need UM coverage when they already have health insurance. The coverages overlap but aren’t substitutes:

Loss after an uninsured-driver crash	Health insurance	PIP / Med-pay	UM/UIM
Your medical bills	Yes (minus deductibles/copays)	Yes (up to PIP limits)	Yes (up to UM limits)
Lost wages	No	Yes, partially (PIP)	Yes
Pain and suffering	No	No	Yes
Passengers’ injuries	Limited	Yes	Yes
Your car’s damage	No	No	Only with UM property-damage coverage

Health insurance stops at medical bills. PIP (required in no-fault states) covers medical plus some lost wages up to its limits — but PIP limits are often modest ($10,000 in some states). UM/UIM is the only coverage in the stack that addresses the full picture: medical gaps, lost income, and non-economic losses. They layer rather than duplicate.

Hit-and-run: what to do step by step

Hit-and-runs are treated as uninsured-driver claims under most UM policies — but they come with extra requirements:

1. Call the police immediately. Insurers typically require a police report for hit-and-run UM claims. The longer you wait, the harder the claim gets.
2. Document everything. Photos of the damage, the location, debris, paint transfer, and any witnesses. Note the fleeing vehicle’s description — even partial plate characters help.
3. Look for cameras. Ask nearby businesses for security footage quickly; most systems overwrite within days.
4. Notify your insurer promptly. Report it as a potential UM claim, not just a collision claim — the coverage invoked affects your deductible and rate impact.
5. Get checked medically even if you feel fine. Adrenaline masks injuries; a same-day medical record also protects the injury portion of the claim.

One caution: some states impose a short deadline for reporting hit-and-runs to police (sometimes 24 hours) as a condition of UM coverage. Don’t sleep on it.

UM in no-fault states

In no-fault states, your own PIP covers your initial medical bills regardless of fault — which leads some drivers to think UM is redundant there. It isn’t: PIP limits are often low, PIP doesn’t cover pain and suffering or the full scope of lost wages, and UM still covers the serious-injury scenarios where no-fault thresholds are exceeded and lawsuits become possible. Several no-fault states mandate UM/UIM anyway. If you live in one, treat UM as the coverage that takes over where PIP runs out.

FAQ

Is uninsured motorist coverage required?

In 20 states plus DC, yes (for at least some form of UM/UIM). Elsewhere it’s optional but usually must be offered. Check your state’s current requirements with its insurance department.

Does uninsured motorist coverage cover hit-and-run?

Yes — hit-and-run drivers are treated as uninsured under UM coverage in most states. File a police report promptly; insurers typically require one for hit-and-run UM claims.

What’s the difference between UM and UIM?

UM applies when the at-fault driver has no insurance at all. UIM applies when they have insurance but their liability limits are lower than your losses — it pays the difference up to your UIM limits.

Should I get uninsured motorist coverage if I have health insurance?

Health insurance covers medical bills (with cost-sharing), but it doesn’t cover lost wages, and it doesn’t cover passengers the same way. UM/UIM fills those gaps and is typically inexpensive. Most consumer guides treat it as essential.

How much uninsured motorist coverage do I need?

A common approach is matching your liability limits (e.g., 100/300). State minimums for UM can be exhausted quickly by serious injuries, so drivers with assets or high medical exposure often carry more.

Does UM coverage raise my premium much?

No — UM/UIM is consistently one of the least expensive coverages on a policy relative to its limits. Raising UM from state minimums to 100/300 typically costs a small fraction of what the equivalent liability increase costs.

Can I stack UM coverage across multiple cars?

In some states, yes. Stacking combines the UM limits of each vehicle on your policy — two cars with 50/100 UM become 100/200 of effective coverage. Availability and cost vary by state and insurer; ask your agent whether your state permits it.

This is general information, not financial advice — check your state’s insurance department for rules that apply to you.