If you are relocating the United States, it is important to know that the US does not require all expatriates (or US citizens) to have medical coverage. However, the risk of being in the US without medical coverage is massive hospital bills or even no access to medical care. There are newer requirements for certain expats on select visa types that may require you to have health coverage.
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 maxima. In these cases, the health plan will stop payment when they reach the benefit maximum, and the policy-holder must pay all remaining costs.
Types of Coverage: All of the health plans sold through the Marketplace are offered by private insurance companies and are required to meet minimum requirements. All of the plans are required to cover a comprehensive set of benefits that includes hospital care, doctors’ visits, emergency care, prescription drugs, lab services, preventive care, and rehabilitative services. Before choosing a plan, individuals will be able to see whether their healthcare practitioner participates in the plan’s network (if choosing a network plan). Individuals will be able to choose the plan that best meets their needs and budget. Individuals with low-incomes may instead qualify for free or low-cost coverage through Medicaid or the Children’s Health Insurance Program. 
Efforts to pass a national pool were unsuccessful for many years. With the Patient Protection and Affordable Care Act, it became easier for people with pre-existing conditions to afford regular insurance, since all insurers are fully prohibited from discriminating against or charging higher rates for any individuals based on pre-existing medical conditions.[31][32] Therefore, most of the state-based pools shut down.[33] As of 2017, some remain due to statutes which have not been updated, but they also may cover people with gaps in coverage such as undocumented immigrants[33] or Medicare-eligible individuals under the age of 65.[33]
^ Bump, Jesse B. (19 October 2010). "The long road to universal health coverage. A century of lessons for development strategy" (PDF). Seattle: PATH. Retrieved 10 March 2013. Carrin and James have identified 1988—105 years after Bismarck's first sickness fund laws—as the date Germany achieved universal health coverage through this series of extensions to minimum benefit packages and expansions of the enrolled population. Bärnighausen and Sauerborn have quantified this long-term progressive increase in the proportion of the German population covered by public and private insurance. Their graph is reproduced below as Figure 1: German Population Enrolled in Health Insurance (%) 1885–1995.
The proportion of non-elderly individuals with employer-sponsored cover fell from 66% in 2000 to 56% in 2010, then stabilized following the passage of the Affordable Care Act. Employees who worked part-time (less than 30 hours a week) were less likely to be offered coverage by their employer than were employees who worked full-time (21% vs. 72%).[7]