Medicare Advantage plans expand the health insurance options for people with Medicare. Medicare Advantage was created under the Balanced Budget Act of 1997, with the intent to better control the rapid growth in Medicare spending, as well as to provide Medicare beneficiaries more choices. But on average, Medicare Advantage plans cost 12% more than traditional Medicare.[48] The ACA took steps to align payments to Medicare Advantage plans with the cost of traditional Medicare.

Effective group health plan years beginning after September 23, 2010, if an employer-sponsored health plan allows employees' children to enroll in coverage, then the health plan must allow employees' adult children to enroll as well as long as the adult child is not yet age 26. Some group health insurance plans may also require that the adult child not be eligible for other group health insurance coverage, but only before 2014.[78]

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.[23][24] As of 2016, 85% of the population is covered by the compulsory Statutory Health Insurance (SHI)[25] (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.[26] 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.[23][27]
A health maintenance organization (HMO) is a type of managed care organization (MCO) that provides a form of health care coverage that is fulfilled through hospitals, doctors, and other providers with which the HMO has a contract. The Health Maintenance Organization Act of 1973 required employers with 25 or more employees to offer federally certified HMO options.[94] Unlike traditional indemnity insurance, an HMO covers only care rendered by those doctors and other professionals who have agreed to treat patients in accordance with the HMO's guidelines and restrictions in exchange for a steady stream of customers. Benefits are provided through a network of providers. Providers may be employees of the HMO ("staff model"), employees of a provider group that has contracted with the HMO ("group model"), or members of an independent practice association ("IPA model"). HMOs may also use a combination of these approaches ("network model").[19][95]
The US health insurance market is highly concentrated, as leading insurers have carried out over 400 mergers from the mid-1990s to the mid-2000s (decade). In 2000, the two largest health insurers (Aetna and UnitedHealth Group) had total membership of 32 million. By 2006 the top two insurers, WellPoint (now Anthem) and UnitedHealth, had total membership of 67 million. The two companies together had more than 36% of the national market for commercial health insurance. The AMA has said that it "has long been concerned about the impact of consolidated markets on patient care." A 2007 AMA study found that in 299 of the 313 markets surveyed, one health plan accounted for at least 30% of the combined health maintenance organization (HMO)/preferred provider organization (PPO) market. In 90% of markets, the largest insurer controls at least 30% of the market, and the largest insurer controls more than 50% of the market in 54% of metropolitan areas.[116] The US Department of Justice has recognized this percentage of market control as conferring substantial monopsony power in the relations between insurer and physicians.[117]
Accident insurance was first offered in the United States by the Franklin Health Assurance Company of Massachusetts. This firm, founded in 1850, offered insurance against injuries arising from railroad and steamboat accidents. Sixty organizations were offering accident insurance in the US by 1866, but the industry consolidated rapidly soon thereafter. While there were earlier experiments, sickness coverage in the US effectively dates from 1890. The first employer-sponsored group disability policy was issued in 1911, but this plan's primary purpose was replacing wages lost because the worker was unable to work, not medical expenses.[19]

The share of Americans without health insurance has been cut in half since 2013. Many of the reforms instituted by the Affordable Care Act of 2010 were designed to extend health care coverage to those without it; however, high cost growth continues unabated.[3] National health expenditures are projected to grow 4.7% per person per year from 2016 to 2025. Public healthcare spending was 29% of federal mandated spending in 1990 and 35% of it in 2000. It is also projected to be roughly half in 2025.[4]