Insured drivers are protected by their uninsured-underinsured motorist accident coverage if the other driver was at fault and was either uninsured or underinsured
Most states require car insurance companies to offer UMI liability motorist coverage. In states that have a fault-based system of insurance, Under-Insured coverage allows the insured driver with higher liability limits to recover not only the insurance limits from the driver at fault but also from their own insurance company up to their own UMI policy limits. When the fault is by an Uninsured driver, the insured driver can collect up to the insured driver’s UMI coverage.
For example, the driver at fault might have liability limits of just $15,000, but you have uninsured motorist limits of $100,000. You will need to settle with the other driver’s insurance company for $15,000 first and then make a UMI claim against your insurance company for up to the limit of your policy of $100,000, minus the $15,000 already recovered by the other driver.