The IRS has issued an explanation of which U.S. citizens and foreign nationals are 
subject to the individual shared responsibility provision of the Affordable Care Act, or the “individual mandate.”
The ACA requires anyone who is subject to the mandate to have qualifying health insurance for the entire year; to have a health coverage exemption; or to make a payment when they file their tax returns.
All U.S. citizens living in the United States are subject to the individual shared responsibility provision.
Children are also subject to the mandate. Each child must have minimum essential coverage or must qualify for an exemption for each month in the calendar year. If the child does not, the adult or couple who claims the child as a dependent will generally owe a shared responsibility payment for the child.
Senior citizens are subject to the individual shared responsibility provision. However, both Medicare Part A and Medicare Part C (also known as Medicare Advantage), qualify as minimum essential coverage.
Permanent residents and foreign nationals who are in the United States long enough during a calendar year to qualify as resident aliens for tax purposes are subject to the mandate.
Individuals who are not lawfully present in the United States are exempt from the individual mandate.
An immigrant with Deferred Action for Childhood Arrivals status is considered not lawfully present, so is exempt even if he or she has a social security number. These individuals should claim coverage exemptions on Form 8965, Health Coverage Exemptions.
Foreign nationals who live in the United States for a short enough period that they do not become resident aliens for federal income tax purposes are not subject to the mandate, even if they have to file a U.S. income tax return.
U.S. citizens living abroad are subject to the individual shared responsibility provision. However, if these citizens are not physically present in the United States for at least 330 full days within a 12-month period, they are treated as having minimum essential coverage for that 12-month period.
U.S. citizens who are residents of a foreign country or countries for an entire taxable year are treated as having minimum essential coverage for that year.
Residents of the United States territories are treated by law as having minimum essential coverage.
The IRS has an online Interactive Tax Assistant to help individuals see if they are subject to the individual mandate, as well as a set of questions and answers about the provision.
