A health insurance policy is a contract between an insurance company and an individual or his sponsor (e.g. an employer). The contract can be renewable annually or monthly. The type and amount of health care costs that will be covered by the health insurance company are specified in advance, in the member contract or "Evidence of Coverage" booklet. The individual insurered person's obligations may take several forms:

•    Deductible: The amount that the insured must pay out-of-pocket before the health insurer pays its share. For example, a policy-holder might have to pay a $500 deductible per year, before any of their health care is covered by the health insurer. It may take several doctor's visits or prescription refills before the insured person reaches the deductible and the insurance company starts to pay for care.
•    Copayment: The amount that the insured person must pay out of pocket before the health insurer pays for a particular visit or service. For example, an insured person might pay a $45 copayment for a doctor's visit, or to obtain a prescription. A copayment must be paid each time a particular service is obtained.
•    Coinsurance: Instead of, or in addition to, paying a fixed amount up front (a copayment), the co-insurance is a percentage of the total cost that insured person may also pay. For example, the member might have to pay 20% of the cost of a surgery over and above a co-payment, while the insurance company pays the other 80%. If there is an upper limit on coinsurance, the policy-holder could end up owing very little, or a great deal, depending on the actual costs of the services they obtain.
•    Coverage limits: Some health insurance policies only pay for health care up to a certain dollar amount. The insured person may be expected to pay any charges in excess of the health plan's maximum payment for a specific service. In addition, some insurance company schemes have annual or lifetime coverage maximums. In these cases, the health plan will stop payment when they reach the benefit maximum, and the policy-holder must pay all remaining costs.
•    Out-of-pocket maximums: Similar to coverage limits, except that in this case, the insured person's payment obligation ends when they reach the out-of-pocket maximum, and the health company pays all further covered costs. Out-of-pocket maximums can be limited to a specific benefit category (such as prescription drugs) or can apply to all coverage provided during a specific benefit year.
•    Prior Authorization: A certification or authorization that an insurer provides prior to medical service occurring. Obtaining an authorization means that the insurer is obligated to pay for the service, assume it matches what was authorized. Many smaller, routine services do not require authorization.