Public programs provide the primary source of coverage for most seniors and also low-income children and families who meet certain eligibility requirements. The primary public programs are Medicare, a federal social insurance program for seniors (generally persons aged 65 and over) and certain disabled individuals; Medicaid, funded jointly by the federal government and states but administered at the state level, which covers certain very low income children and their families; and CHIP, also a federal-state partnership that serves certain children and families who do not qualify for Medicaid but who cannot afford private coverage. Other public programs include military health benefits provided through TRICARE and the Veterans Health Administration and benefits provided through the Indian Health Service. Some states have additional programs for low-income individuals. In 2011, approximately 60 percent of stays were billed to Medicare and Medicaid—up from 52 percent in 1997.
Provider networks can be used to reduce costs by negotiating favorable fees from providers, selecting cost effective providers, and creating financial incentives for providers to practice more efficiently. A survey issued in 2009 by America's Health Insurance Plans found that patients going to out-of-network providers are sometimes charged extremely high fees.
Historically, health insurance has been regulated by the states, consistent with the McCarran-Ferguson Act. Details for what health insurance could be sold were up to the states, with a variety of laws and regulations. Model acts and regulations promulgated by the National Association of Insurance Commissioners (NAIC) provide some degree of uniformity state to state. These models do not have the force of law and have no effect unless they are adopted by a state. They are, however, used as guides by most states, and some states adopt them with little or no change.
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.