A Health insurance policy is a contract between an insurance company and an individual. The contract can be renewable annually or monthly. The type and amount of health care costs that will be covered by the health plan are specified in advance, in the member contract or Evidence of Coverage booklet. The individual policy-holder's payment obligations may take several forms:
-Premium: The amount the policy-holder pays to the health plan each month to purchase health coverage.
-Deductible: The amount that the policy-holder must pay out-of-pocket before the health plan 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 plan. It may take several doctor's visits or prescription refills before the policy-holder reaches the deductible and the health plan starts to pay for care.
-Copayment: The amount that the policy-holder must pay out of pocket before the health plan pays for a particular visit or service. For example, a policy-holder 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 paying a fixed amount up front (a copayment), the policy-holder must pay a percentage of the total cost. For example, the member might have to pay 20% of the cost of a surgery, while the health plan pays the other 80%. Because there is no upper limit on coinsurance, the policy-holder can end up owing very little, or a significant amount, depending on the actual costs of the services they obtain.
-Exclusions: Not all services are covered. The policy-holder is generally expected to pay the full cost of non-covered services out of their own pocket.
-Coverage limits: Some health plans only pay for health care up to a certain dollar amount. The policy-holder may be expected to pay any charges in excess of the health plan's maximum payment for a specific service. In addition, some plans 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 member's payment obligation ends when they reach the out-of-pocket maximum, and the health plan 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.
Prescription drug plans are a form of insurance offered through many employer benefit plans in the U.S., where the patient pays a copayment and the prescription drug insurance pays the rest.
Some health care providers will agree to bill the insurance company if patients are willing to sign an agreement that they will be responsible for the amount that the insurance company doesn't pay, as the insurance company pays according to "reasonable" or "customary" charges, which may be less than the provider's usual fee.
Health insurance companies also often have a network of providers who agree to accept the reasonable and customary fee and waive the remainder. It will generally cost the patient less to use an in-network provider.
Health plan vs. health insurance
Historically, HMOs tended to use the term "health plan", while commercial insurance companies used the term "health insurance". A health plan can also refer to a subscription-based medical care arrangement offered through health maintenance organization,HMO, PPO, or POS plan. These plans are similar to pre-paid dental, pre-paid legal, and pre-paid vision plans. Pre-paid health plans typically pay for a fixed number of services (for instance, $300 in preventive care, a certain number of days of hospice care or care in a skilled nursing facility, a fixed number of home health visits, a fixed number of spinal manipulation charges, etc.) The services offered are usually at the discretion of a utilization review nurse who is often contracted through the managed care entity providing the subscription health plan. This determination may be made either prior to or after hospital admission (concurrent utilization review).
Inherent problems with insurance
Insurance systems must typically deal with two inherent challenges: adverse selection, which affects any voluntary system, and ex-post moral hazard, which affects any insurance system in which a third party bears major responsibility for payment, whether that is an employer or the government. Some national systems with compulsory insurance utilize systems of risk equalization to overcome these inherent problems.
Insurance companies use the term "adverse selection" to describe the tendency for only those who will benefit from insurance to buy it. Specifically when talking about health insurance, unhealthy people are more likely to purchase health insurance because they anticipate large medical bills. On the other side, people who consider themselves to be reasonably healthy may decide that medical insurance is an unnecessary expense; if they see the doctor once a year and it costs $250, that's much better than making monthly insurance payments of $400 (example figures).
The fundamental concept of insurance is that it balances costs across a large, random sample of individuals (see risk pool). For instance, an insurance company has a pool of 1000 randomly selected subscribers, each paying $100 per month. One person becomes very ill while the others stay healthy, allowing the insurance company to use the money paid by the healthy people to pay for the treatment costs of the sick person. However, when the pool is self-selecting rather than random, as is the case with individuals seeking to purchase health insurance directly, adverse selection is a greater concern. Some individuals have extremely high medical expenses, in extreme cases totaling a half million dollars or more. These represent a relatively small percentage of the insured population, however.  Adverse selection could leave an insurance company with primarily sick subscribers and no way to balance out the cost of their medical expenses with a large number of healthy subscribers.
Because of adverse selection, insurance companies employ medical underwriting, using a patient's medical history to screen out those whose pre-existing medical conditions pose too great a risk for the risk pool. Before buying health insurance, a person typically fills out a comprehensive medical history form that asks whether the person smokes, how much the person weighs, whether the person has been treated for any of a long list of diseases and so on. In general, those who present large financial burdens are denied coverage or charged high premiums to compensate. One large U.S. industry survey found that roughly 13 percent of applicants for comprehensive, individually purchased health insurance who went through the medical underwriting in 2004 were denied coverage. Declination rates increased significantly with age, rising from 5 percent for individuals 18 and under to just under a third for individuals aged 60 to 64. Among those who were offered coverage, the study found that 76% received offers at standard premium rates, and 22% were offered higher rates. On the other side, applicants can get discounts if they do not smoke and are healthy.
Main article: Moral hazard
Moral hazard occurs when an insurer and a consumer enter into a contract under symmetric information, but one party takes action, not taken into account in the contract, which changes the value of the insurance. A common example of moral hazard is third-party payment — when the parties involved in making a decision are not responsible for bearing costs arising from the decision. An example is where doctors and insured patients agree to extra tests which may or may not be necessary. Doctors benefit by avoiding possible malpractice suits, and patients benefit by gaining increased certainty of their medical condition. The cost of these extra tests is borne by the insurance company, which may have had little say in the decision. Co-payments, deductibles, and less generous insurance for services with more elastic demand attempt to combat moral hazard, as they hold the consumer responsible.
Other factors affecting insurance prices
A recent study by PriceWaterhouseCoopers examining the drivers of rising health care costs in the U.S. pointed to increased utilization created by increased consumer demand, new treatments, and more intensive diagnostic testing, as the most significant driver. People in developed countries are living longer. The population of those countries is aging, and a larger group of senior citizens requires more intensive medical care than a young healthier population. Advances in medicine and medical technology can also increase the cost of medical treatment. Other factors that increase utilization and therefore insurance prices are lifestyle-related: increases in obesity caused by insufficient exercise and unhealthy food choices; excessive alcohol use, smoking, and use of street drugs. Other factors noted by the PWC study included the movement to broader-access plans, higher-priced technologies, and cost-shifting from Medicaid and the uninsured to private payers.