Occurrence basis: A liability coverage form that covers claims that occur during the policy period, and for which claims can be reported to the insurance company at any time during or after the policy period.

Open access: Allow members to see participating providers, usually a specialist, without a referral from the health plan's gatekeeper. These types of arrangements are most often found in IPA-model HMOs.

Out of network: Services received from a provider who does not participate with the enrollee's health plan.

Out-of-pocket expenses or costs: The share of health services payments paid by the enrollee.

Out-of pocket maximum: The maximum amount a covered person will pay annually for expenses not covered by the health insurance policy.

Out-of-pocket maximum or cap: An annual limit on how much in deductibles and co-payments the patient is required to pay.