Uninsured/Underinsured Motorist (UM/UIM) coverage protects you when the person who caused your accident either has no insurance at all or doesn't have enough to cover your injuries. It steps into the shoes of the at-fault driver's missing coverage, so you aren't left paying for someone else's mistake. It's part of your own auto policy, even though it responds to another driver's fault.

UM vs. UIM

• Uninsured Motorist (UM) applies when the at-fault driver has no liability insurance (or in many states, when a hit-and-run driver can't be identified).
• Underinsured Motorist (UIM) applies when the at-fault driver has insurance, but their limits are too low to cover all your damages. Your UIM coverage helps fill the gap.

Why it matters

Plenty of drivers on the road carry minimal coverage or none at all. Without UM/UIM, a serious injury caused by one of them could leave you with medical bills and lost wages and no one able to pay them. UM/UIM turns your own policy into a safety net.

A simple example

A driver with no insurance runs a red light and totals your car, injuring your back. Because the at-fault driver can't pay, your Uninsured Motorist coverage pays for your injuries as if it were the at-fault driver's liability policy—up to your UM limit.

Don't confuse it with…

UM/UIM is first-party coverage on your policy that pays you, even though the loss was someone else's fault—a slightly unusual combination. It's different from collision coverage (which repairs your car regardless of fault) and from liability coverage (which pays others when you're at fault).

On the exam

Remember the trigger words: UM = no insurance, UIM = not enough insurance. Know that hit-and-run is often treated under UM, and that this coverage protects you against the other driver's failure to carry adequate insurance.