Coverage for bodily injury (BI) and, in some states, property damage (PD) incurred by an insured when an accident is caused by a motorist who is not sufficiently insured. Depending on the jurisdiction, UIM coverage may be written with a limits trigger or a damages trigger.
With a limits trigger, UIM coverage applies when the limits of liability carried by the other motorist are lower than the UIM limits carried by the insured. With a damages trigger, UIM coverage applies when the insured’s damages are more than the at-fault party’s available limits.