42 CFR § 136.61 - Payor of last resort.
(a) The Indian Health Service is the payor of last resort for persons defined as eligible for contract health services under the regulations in this part, notwithstanding any State or local law or regulation to the contrary.
(b) Accordingly, the Indian Health Service will not be responsible for or authorize payment for contract health services to the extent that:
(3) The Indian would be eligible for alternate resources under State or local law or regulation but for the Indian's eligibility for contract health services, or other health services, from the Indian Health Service or Indian Health Service funded programs.
(c) Alternate resources means health care resources other than those of the Indian Health Service. Such resources include health care providers and institutions, and health care programs for the payment of health services including but not limited to programs under titles XVIII or XIX of the Social Security Act (i.e., Medicare, Medicaid), State or local health care programs, and private insurance.