The Affordable Care Act requires all Americans to participate in some form of health care insurance, or else pay an annual tax penalty. People who are recognized by the federal government as Native American are generally exempt form the tax penalty, which will reach a minimum of $695 when fully implemented, because most Native Americans are eligible for some form of health care from the federal Indian Health Service. However, the definition of “Indian” under the Affordable Care Act is limited to those who can document their membership in one of about 560 tribes recognized by the U.S. Bureau of Indian Affairs.

This federal definition is creating a significant gap that could force many Native Americans to pay the tax penalty. More than 100 tribes nationwide are recognized only by states and not the federal government, leaving their members outside the federal definition. Many tribes do not allow their members to enroll before they are 18, meaning some school-age children whose parents are Native American might not come within the definition in the act. Other tribal governments have complicated blood-quantum requirements or rules that all members must live on the reservation, even though nearly two-thirds of Native Americans and Alaska Natives now live in metropolitan areas.

The definition of “Indian” in the Affordable Care Act is roiling emotions on reservations and in native enclaves across the country, but U.S. Department of Health and Human Services spokeswoman Erin Shields said the agency is powerless to change it without an act of Congress. The problem is so new that the federal government is still seeking to establish how many people might be affected, although Indian health advocacy groups estimate it could be up to 480,000.

"We have and will continue to encourage a robust dialogue with American Indian and Alaska Native communities about this matter, and welcome their input and ideas for solutions," Shields said in a statement to The Associated Press. "Under the law, it would require a legislative rather than regulatory change to address this matter. And as we consider approaches to the best possible solution, we are eager to work with Congress."

The IRS has not yet decided how the agency will verify who qualifies as “Indian”, or how it will assess the penalty on tax returns. The IRS and U.S. Treasury have scheduled a May 29 public hearing on their proposed rules establishing who qualifies for an exemption from the insurance coverage requirement.

Republican Rep. Tom Cole, a member of the Chickasaw Nation in Oklahoma and one of just two federal legislators who are members of a federally recognized tribe, said he was aware of the concerns and would ensure that care for native people was not compromised as the health overhaul rolls out. He declined to comment about whether he would sponsor a bill to address the issue. "This could lead to some tribal citizens being required to purchase insurance or face penalties even though they are covered by IHS," he said in a statement to The Associated Press, referring to the federal Indian Health Service. "I am watching the situation closely to ensure that those individuals already benefiting from care through IHS continue to receive it."

The 2010 Census found that nearly one-third of the 6.2 million people who self-identify as American Indian or Alaska Native lack health insurance and that 28 percent live in poverty.