Occurrence

The occurrence is the triggering event that activates coverage under an occurrence-based insurance policy such as the standard commercial general liability form (ISO CG 00 01). Under this form, an occurrence is defined as an accident, including continuous or repeated exposure to substantially the same general harmful conditions. This broad definition is significant for apartment owners because many claims involve ongoing conditions—such as mold growth from a persistent leak, lead paint exposure over months, or repeated slip-and-fall incidents on the same defective surface—rather than single discrete events.

Determining when an occurrence took place and how many occurrences are involved in a series of related events has major implications for coverage. Each occurrence is subject to a separate per-occurrence limit and a separate deductible. If ten tenants are injured when a balcony collapses, that is typically one occurrence with one deductible, and the combined claims are subject to one per-occurrence limit. If ten tenants are injured in ten separate slip-and-fall incidents over the course of a year, those are ten separate occurrences, each with its own deductible and per-occurrence limit, all subject to the policy's annual aggregate.

Apartment owners benefit from the occurrence-based policy structure because coverage is triggered by when the event happens, not when the claim is reported. An occurrence-based policy will respond to a claim reported years after the policy expires, as long as the occurrence took place during the policy period. This eliminates the need for tail coverage that claims-made policies require, making occurrence-based policies administratively simpler and providing more durable long-term protection.