Uninsured Motorist Coverage Explained: UM, UIM and What States Require

Uninsured motorist coverage pays for your own losses when a driver who causes a crash has no insurance, or when a hit-and-run driver hits you. Its companion, underinsured motorist coverage, pays when the at-fault driver has insurance but not enough to cover your loss ¹. The two are often sold together and abbreviated UM and UIM.

Whether you must carry it depends on your state. Some states require it on every policy, others require insurers to offer it and let you turn it down in writing, and the rules on limits and property damage differ from state to state ^{1 6}. The details below come from state insurance regulators and statutes, with a few examples.

Liability insurance pays for the harm you cause to other people. UM and UIM turn that around: they pay you, and usually your passengers, when someone else causes the crash and cannot pay ^{1 3}. The Texas Department of Insurance describes the coverage as paying "if you're hit by someone who didn't have insurance or didn't have enough to pay your medical and car repair bills" ².

The coverage usually comes in two parts:

• Uninsured motorist bodily injury (UMBI). Pays for injuries to you and the people in your car. In California, the state insurance department says the UMBI limits are the same as your liability coverage limits ³.
• Uninsured motorist property damage (UMPD). Pays for damage to your car. The rules for it vary by state. California's department lists a UMPD limit of $3,500 and says it only pays if the uninsured driver is identified ³.

Like other coverages, UM and UIM have dollar limits, which cap what the insurer pays. In Texas, a deductible also applies to uninsured/underinsured motorist claims, according to the state's auto guide ².

Uninsured means no liability coverage at all. Underinsured means the other driver's liability limits are lower than your losses ¹. A driver who carries only a state minimum, for example, may have far less coverage than the cost of a serious injury. UIM is designed for that gap; how much it pays depends on the state and the policy wording. Your declarations page and policy show which version you have.

There are two broad approaches. Here are examples from official sources:

Florida's statute adds that the coverage limits must be not less than the bodily injury liability limits you buy unless you select lower limits or reject it ⁴. In Texas, the same written-rejection rule applies to personal injury protection, which every Texas auto policy includes unless you turn it down in writing ².

Nationally, the Insurance Information Institute says that 20 states and the District of Columbia have mandatory requirements for uninsured or underinsured motorist coverage, and it advises checking with the state insurance department to confirm what is compulsory ⁶. Requirements change, so your state insurance department or the declarations page of your policy is the place to confirm what applies to you.

The Insurance Research Council estimates that in 2023, 15.4 percent of motorists, more than one in seven drivers, were uninsured, according to the Insurance Information Institute ⁶.

The share varies widely by state. The same source lists Mississippi at 28.2%, New Mexico at 24.1% and the District of Columbia at 23.1% as the highest for 2023, and Maine at 5.7%, Utah at 6.2% and Idaho at 6.4% as the lowest ⁶. These are estimates built from claims data, not a count of every driver, and they describe a state as a whole rather than any one road or neighborhood.

UM and UIM add a line to your premium. What that line costs depends on the limits you choose, the state, where the car is kept and how often uninsured drivers cause claims there. Each insurer prices it in its own way.

A few points to weigh when reading a renewal or a quote:

• Check the limits. In some states UM limits follow your liability limits unless you pick lower ones ^{3 4}. Raising liability limits may raise UM limits, and the price, with them.
• Look for a rejection form. In must-offer states, turning the coverage down is done in writing ^{2 3 4}. If you signed one in the past, your policy may not include UM at all.
• Compare overlapping coverage. Collision coverage, medical payments and personal injury protection can pay some of the same costs. Knowing what each covers helps you decide what limits make sense.

If your bill went up and UM or UIM is one of the lines that changed, our guide on why car insurance goes up explains the other common causes, and our explainer on minimum versus full coverage covers how the coverages you choose shape the total.

This article explains how the coverage works, not what to do after an accident. Questions about a specific claim or crash belong with your insurer, and if you have a concern about how a claim is being handled, your state insurance department can help. In Texas, that is the Texas Department of Insurance ²; in California, the California Department of Insurance ³.

• ¹ Official record: NAIC consumer article defining uninsured and underinsured motorist coverage and noting some states require it, checked October 11, 2026.
• ² Official record: Texas Department of Insurance auto guide on UM/UIM (must be offered, rejection in writing, deductible, limits) and PIP rejection, checked October 11, 2026.
• ³ Official record: California Department of Insurance consumer guide on who UMBI covers, UMBI limits, the $3,500 UMPD limit and the signed waiver, checked October 11, 2026.
• ⁴ Official record: Florida Statutes section 627.727 on uninsured motor vehicle coverage, written rejection and limits, checked October 11, 2026.
• ⁵ Official record: New York State Department of Financial Services FAQ on required liability minimums and uninsured motorists coverage, checked October 11, 2026.
• ⁶ Reported: Insurance Information Institute summary of Insurance Research Council estimates of uninsured motorists for 2023 (national 15.4 percent and state shares) and its count of states with mandatory UM/UIM requirements, checked October 11, 2026.