Umbrella Cover

(1) Cover providing excess limits over the normal limits of liability policies and giving additional excess cover for perils not insured by the primary liability policies. (2) In reinsurance cover against an accumulation of losses under one or more classes of insurance arising out of a single event.
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UK: Takes the form of excess of loss reinsurance treaty to protect the reinsured against an accumulation of retained losses arising from one event under different classes of businesses. Example: A storm causing widespread losses affecting property, motor, marine and aviation accounts. Alternative terms: whole account; back-up cover.

Umbrella liability policy

Liability policy with high limits covering over the top of underlying, primary, liability insurances subject to a self-insured retention. Cover is usually broader than the primary cover and may have a drop down provision.
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A policy designed to provide protection against catastrophic losses. It generally is written over various primary liability policies, such as the business auto policy (BAP), commercial general liability (CGL) policy, watercraft and aircraft liability policies, and employers liability coverage. The umbrella policy serves three purposes it provides excess limits when the limits of underlying liability policies are exhausted by the payment of claims it drops down and picks up where the underlying policy leaves off when the aggregate limit of the underlying policy in question is exhausted by the payment of claims and it provides protection against some claims not covered by the underlying policies, subject to the assumption by the named insured of a self-insured retention (SIR).

Umpire

In case the insurer and claimant fail to agree on the quantum of loss they appoint one arbitrator each. These two arbitrators select one Umpire. A decision by any two of the three is binding.

UN

HCPCS Level II modifier that may be used with CPT or HCPCS Level II codes indicating two patients served.