When the person at fault for an accident does not have insurance, Uninsured Motorist Bodily Injury will cover injuries and damages you incur that the at-fault party is legally liable for, such as medical treatment and lost wages up to the limits you select.
If your injury expenses exceed the at-fault party's Liability limits, you can use Underinsured Motorist Bodily Injury coverage to pay for the amount not covered by the at-fault person's insurance. Similar to Uninsured Motorist coverage, Underinsured Motorist coverage is designed to cover the gap between the other person's Liability limits and the amount of your injury expenses, up to the Underinsured Motorist limits you select.
If the driver or owner of a vehicle is legally liable for an accident but does not have insurance or does not have enough insurance, you can use Uninsured/Underinsured Motorist Property Damage (UMPD) to cover damage to your insured auto, up to the limits you select. In some states, UMPD is available as an alternative to Collision coverage. Certain exclusions may apply. Refer to your policy.
Example:
A driver who has no insurance rear-ends your car while you're sitting at a stop sign. Your car has $2,000 in damage. You go to the doctor because your neck is hurting, and your total medical bills equal $300. Your Uninsured Motorist limits are $20,000/$40,000/$15,000, which means your injuries and the damage to your car fall within these limits and will be covered.