France's generous pension system has toppled governments there over questions of how to fund it. It's part of a broader problem, as nations rethink how to fund care for their aging populations.

If lawmakers push to charge retirees for health care, it will especially hit Americans who have made France their home.

French retirees officially bring in more income than their working-aged counterparts, as Americans are struggling to find the funds to retire and support their post-employment lifestyle. Due to France ...