Uninsured & Underinsured Motorist Coverage: What It Actually Pays and the 13 States That Require It

What UM/UIM coverage actually does

Uninsured Motorist (UM) and Underinsured Motorist (UIM) coverage pays your medical bills, lost wages, and pain-and-suffering when an at-fault driver either has no insurance at all or has too little insurance to cover your damages. Without it, you're stuck suing an uninsured driver who almost by definition has no assets to seize.

According to the Insurance Research Council, 12.6% of U.S. drivers were uninsured in the most recent reporting year — and that number jumps above 20% in Mississippi, Michigan, Tennessee, and New Mexico. Underinsured drivers (those carrying only state-minimum limits, often $25K bodily injury) effectively act uninsured in any serious collision, because a single ER visit + ambulance + follow-up surgery routinely exceeds $50K.

UM vs UIM — they pay in different situations

Uninsured Motorist (UM) kicks in when the at-fault driver has zero liability coverage, fled the scene (hit-and-run), or their insurer denies the claim because of policy lapse / fraud.

Underinsured Motorist (UIM) kicks in when the at-fault driver HAS insurance, but their limits are too low to cover your damages. Example: the other driver carries the Texas minimum of $30K bodily-injury per person, your hospital bill is $87K, and you collect the first $30K from their carrier — your UIM then pays the remaining $57K (up to your UIM limit).

Most carriers bundle UM + UIM into a single coverage line, but a dozen states let you split them. If your state offers a split, buy both at matching limits — the price difference is usually $20-40 per six-month term.

The 13 states (+ D.C.) where UM coverage is mandatory

Connecticut, D.C., Illinois, Kansas, Maine, Maryland, Massachusetts, Minnesota, Missouri, Nebraska, New Hampshire (if you buy any liability), New York, North Carolina, Oregon, South Carolina, Vermont, Virginia, West Virginia, and Wisconsin.

In another 17 states, carriers must OFFER UM coverage to you in writing and you must explicitly reject it in writing — so check the rejection waiver in your file if your policy doesn't have UM and you don't remember declining.

What limits should you actually buy?

Match your UM/UIM limits to your liability limits. If you carry 100/300 liability (a sensible mid-tier), buy 100/300 UM/UIM. The reasoning: your assets matter to your liability decision (you have $X you want to protect from a lawsuit). When YOU'RE the one hurt, the same $X of assets and future earnings need protection from an uninsured driver who hits you. The risk pool is symmetric.

State minimums (often 25/50) are a trap here. If you live in California or Texas — where 1-in-7 drivers are uninsured — your UM/UIM should be at LEAST 100/300, ideally 250/500.

Stacking UM coverage across multiple vehicles

Twenty-six states allow "stacking" — combining the UM limits across every vehicle on your policy. If you carry 100/300 UM on three vehicles, a stacking state lets you collect up to $300K per person when one of them is hit. Carriers will quietly de-stack you on renewal unless you explicitly say "I want stacked UM."

Non-stacking states: Florida, Pennsylvania, Indiana, California, and Texas (with conditions). Stacking states include New York, Illinois, Washington, Georgia, Arizona, Tennessee, and most New England states.

How a UM/UIM claim actually plays out

1. You file with YOUR insurer (not the other driver's, even if they have coverage — your UIM only pays the gap above their limits)
2. Your carrier opens a claim and may require an Examination Under Oath (EUO), a deposition-style interview
3. You collect from the at-fault driver's policy first, up to their limits
4. Your UIM pays the gap between their limits and your damages, up to YOUR UIM cap
5. Total recovery = their liability limits + your UIM limits, NOT just the higher of the two

The biggest UM/UIM claim traps:

• The 2-year notice rule: most carriers require formal UM/UIM notice within 2 years of the accident (some states 1 year). Miss it and you waive the coverage.
• The arbitration clause: 90% of UM/UIM disputes go to binding arbitration, not jury trial — your case is decided by a single arbitrator. Choose a carrier with low arbitration loss rates (data is in NAIC complaint indexes).
• The setoff trap: 11 states let your UIM insurer deduct what the at-fault carrier paid from your UIM payout (instead of stacking). In setoff states, even big UIM limits leave you exposed.

FAQs

Do I need UM coverage if I have great health insurance?

Yes. UM/UIM also pays for lost wages, pain-and-suffering, and out-of-pocket medical costs your health insurance subrogates (claims back) from your settlement. Without UM, you eat the deductible, copays, and any wage loss.

Will my UM premium go up if I file a claim against an uninsured driver?

In most states no — UM claims where you're not at fault legally cannot be surcharged. Confirm in writing if you're in a state that allows surcharging (Indiana, Georgia, and a few others have carve-outs).

Does UM cover passengers in my car?

Yes — UM follows the vehicle. Any passenger injured by the uninsured driver is covered up to your per-person UM limit, with the per-accident limit capping total payouts.

Can I sue the uninsured driver in addition to claiming UM?

Yes, but uninsured drivers rarely have collectable assets. Most plaintiff attorneys won't take the case unless the driver owns real estate. UM is your real recovery path.

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