SAN FRANCISCO (AP) — For decades, the government has paid for American Indians' and Alaska Natives' health care as part of its longstanding treaty obligations to tribes.

But under President Barack Obama's health care overhaul, tens of thousands of Native Americans are about to face a new reality.

They will have to buy their own health insurance policies or pay a $695 fine from the Internal Revenue Service. That is unless they can prove that they are "Indian enough" to claim one of the few exemptions allowed under the Affordable Care Act's mandate that all Americans carry insurance.

The health care overhaul takes a narrow view of who is considered American Indian and can avoid the tax penalty. The definition is limited to people who can prove they belong to one of about 560 tribes recognized by the U.S. Bureau of Indian Affairs.

Copyright 2013 The Associated Press.