The purpose behind the public option was to make more affordable health insurance for uninsured citizens who are either unable to afford the rates of or are rejected by private health insurers. Supporters argued that a government insurance company could successfully lower its rates by using greater leverage than private industry when negotiating with hospitals and doctors, as well as paying the employees of the public option insurance company salaries as opposed to paying based on individual medical procedures.
Before the development of medical expense insurance, patients were expected to pay all other health care costs out of their own pockets, under what is known as the fee-for-service business model. During the middle to late 20th century, traditional disability insurance evolved into modern health insurance programs. Today, most comprehensive private health insurance programs cover the cost of routine, preventive, and emergency health care procedures, and also most prescription drugs, but this was not always the case. The rise of private insurance was accompanied by the gradual expansion of public insurance programs for those who could not acquire coverage through the market.
Beginning with 10% of blue-collar workers in 1885, mandatory insurance has expanded; in 2009, insurance was made mandatory on all citizens, with private health insurance for the self-employed or above an income threshold. As of 2016, 85% of the population is covered by the compulsory Statutory Health Insurance (SHI) (Gesetzliche Krankenversicherung or GKV), with the remainder covered by private insurance (Private Krankenversicherung or PKV) Germany's health care system was 77% government-funded and 23% privately funded as of 2004. While public health insurance contributions are based on the individual's income, private health insurance contributions are based on the individual's age and health condition.
States regulate small group premium rates, typically by placing limits on the premium variation allowable between groups (rate bands). Insurers price to recover their costs over their entire book of small group business while abiding by state rating rules. Over time, the effect of initial underwriting "wears off" as the cost of a group regresses towards the mean. Recent claim experience—whether better or worse than average—is a strong predictor of future costs in the near term. But the average health status of a particular small employer group tends to regress over time towards that of an average group. The process used to price small group coverage changes when a state enacts small group reform laws.
In addition to medical expense insurance, "health insurance" may also refer to insurance covering disability or long-term nursing or custodial care needs. Different health insurance provides different levels of financial protection and the scope of coverage can vary widely, with more than 40% of insured individuals reporting that their plans do not adequately meet their needs as of 2007.