Underinsured Motorist Endorsement (UIM)
Definition - What does Underinsured Motorist Endorsement (UIM) mean?
An underinsured motorist endorsement is an attachment or added provision to an automobile insurance policy. It provides coverage to the policyholder and any passengers in the event of an accident caused by a driver without adequate coverage. In most cases, there is a gap between the insurance coverage of the other driver and the benefit payable under the underinsured motorist coverage. The underinsured motorist endorsement pays for the difference between the two and is subject to the maximum limit of coverage.
It is also known as supplementary underinsured motorist (SUM) coverage or an underinsured motorist clause.
Insuranceopedia explains Underinsured Motorist Endorsement (UIM)
Purchasing underinsured motorist coverage is not mandatory, but it increases the level of protection for policyholders who get into an accident with an at-fault driver who does not have sufficient coverage. If the at-fault party's only has coverage of $100,000 and the insurance claim amounts to $150,000, then this endorsement would pay the insured the difference between the two minus deductibles.