For coverage to be provided, the act giving rise to a claim needs to occur within the policy period. The claim does not need to be reported during the policy period. Used with liability policies.
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A form of reinsurance under which the date of the loss event is deemed to be the date of the occurrence, regardless of when reported. See Claims-made basis.

A liability insurance policy that covers claims arising out of occurrences that take place during the policy period, regardless of when the claim is filed.
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In Liability insurance, a policy that pays for events that occur during its policy term, regardless of which a claim is filed. That is, an expired occurrence policy will pay a valid claim even if the claim is made years late, provided that the event occurred while the policy was in effect.