Affordable Care Act
The Federal Benefits page has a section on how the ACA might impact U.S. citizens living abroad. Here’s the link to that page: https://travel.state.gov/content/travel/en/international-travel/while-abroad/federal-benefits-and-obligations-abroad.html
More links on the ACA:
https://www.healthcare.gov/am-i-eligible-for-coverage-in-the-marketplace/
http://www.irs.gov/uac/Questions-and-Answers-on-the-Individual-Shared-Responsibility-Provision
http://www.irs.gov/uac/Affordable-Care-Act-Tax-Provisions-Home