Both ghost and ajoknoblauch provided "insufficient" answers to this question.
An individual under the age of 65 can receive Social Security (starting at 62) and therefore would not yet be enrolled in Medicare, As a result , they would be required to comply with the rules of Obamacare...(have an approved plan)....until they reach the age of 65.
As far as I know, any US citizen who lives outside the USA for at least 330 (it could be 335) days per year would be exempt.