IHS and Medicare: How Treaty Obligations Meet Federal Health Insurance (And Why Both Matter)

Here's what they don't tell you at Medicare enrollment meetings: if you're American Indian or Alaska Native, you're not choosing between IHS and Medicare — you need both. IHS isn't a government benefit program. It's a treaty obligation, payment for 500 million acres of land that became the United States. But here's the catch: Congress funds IHS at only 60% of documented need, while Medicare Part B costs $185 per month in 2026. The math gets interesting when you realize Medicare actually helps fund IHS facilities through reimbursements — but only if AI/AN elders enroll.

This creates a funding puzzle that affects 2.3 million AI/AN people nationwide, including approximately 400,000 Medicare-eligible elders. When an AI/AN Medicare beneficiary receives care at an IHS facility, Medicare pays the facility directly — bringing additional federal dollars into a chronically underfunded system. It's one of the few examples where enrolling in a federal program helps fund another federal obligation.

IHS vs Medicare: What Each Actually Covers

The coverage gap between IHS and Medicare reveals why both are necessary. IHS provides comprehensive care when available, but resource constraints mean services vary dramatically by location. Medicare provides standardized benefits nationwide, but costs money and has coverage gaps that IHS can fill.

The Purchased/Referred Care Reality Check

When IHS facilities can't provide a service — which happens frequently given staffing shortages and resource constraints — they use the Purchased/Referred Care (PRC) program to refer patients to outside providers. Here's where the money trail gets ugly: PRC operates on a priority system, and funds typically run out before the end of the fiscal year in most areas.

The priority levels work like this: Priority I covers life-threatening emergencies (always funded). Priority II covers disabilities and chronic conditions that significantly impact quality of life. Priority III covers less urgent conditions. Most areas exhaust Priority II funding by June or July, leaving Priority III patients without coverage for the final quarter of the fiscal year.

For AI/AN Medicare beneficiaries, this funding gap becomes irrelevant. When PRC funds run out, Medicare coverage continues. A referral to a cardiologist in August that PRC can't fund gets covered by Medicare Part B (with the standard 20% coinsurance). It's not ideal, but it's better than waiting until October when the new fiscal year begins.

McKinley County: A Case Study in Coverage Gaps

McKinley County, New Mexico, home to parts of the Navajo Nation, illustrates why the IHS-Medicare combination matters. The county has one of the highest AI/AN populations in the country (73.4% according to 2020 census data), but also faces significant healthcare access challenges.

According to HRSA data, McKinley County is designated as a Health Professional Shortage Area for primary care, with a provider-to-population ratio of 1:4,180 (the threshold for adequate access is 1:3,500). For mental health, the ratio is even worse: 1:8,290. The county needs 12 additional primary care providers and 8 additional mental health providers to meet basic access standards.

For Medicare-eligible AI/AN residents in McKinley County, the 2026 Medicare Advantage landscape offers some options, but with limitations. The area has access to 14 Medicare Advantage plans, with premiums ranging from $0 to $89 per month. However, provider networks in rural areas often exclude the specialists that PRC would typically refer to — creating a coverage gap that requires coordination between IHS case managers and Medicare plan navigators.

Why AI/AN Elders Should Enroll in Medicare (Even When They Don't Think They Need It)

The most common mistake among AI/AN elders is thinking they don't need Medicare because they have IHS coverage. This thinking costs both individuals and the broader AI/AN community money. Here's why enrollment makes financial sense:

For the Individual: Medicare provides access to services that IHS can't always deliver — specialists, certain procedures, and brand-name medications. When PRC funds are exhausted, Medicare becomes the backup. The Part B premium of $185 per month might seem expensive, but it's often less than what out-of-pocket specialist visits would cost.

For the Community: Every AI/AN Medicare enrollee who uses IHS services brings Medicare reimbursement dollars into the system. These aren't "instead of" dollars — they're "in addition to" the congressional appropriation. A typical Medicare reimbursement for a primary care visit is $150-250, depending on complexity. Multiply that by thousands of visits, and Medicare reimbursements become a significant funding source for IHS facilities.

The enrollment decision gets more complex for higher-income AI/AN elders. In 2026, individuals with modified adjusted gross income above $106,000 (or married couples above $212,000) pay IRMAA surcharges on top of standard Part B and Part D premiums. For these beneficiaries, the calculation involves weighing the premium cost against the potential for accessing care outside the IHS system and contributing to IHS facility funding.

Medicare Advantage vs Medigap: Special Considerations for AI/AN Beneficiaries

The choice between Medicare Advantage and Medigap (Medicare Supplement Insurance) involves different considerations for AI/AN beneficiaries than for the general Medicare population. Traditional Medicare with Medigap offers the most flexibility for using both IHS facilities and non-IHS providers, but costs more. Medicare Advantage plans cost less (averaging $17.30 per month nationally in 2026) but require navigating provider networks.

For AI/AN beneficiaries, the network issue becomes critical. IHS facilities are typically considered "in-network" for Medicare Advantage plans, but referred specialists might not be. This can create situations where PRC won't pay (because funds are exhausted) and Medicare Advantage won't pay (because the provider is out-of-network). Traditional Medicare avoids this problem by covering any Medicare-participating provider at the same rate.

The prescription drug consideration also differs for AI/AN beneficiaries. IHS pharmacies typically stock generic medications and may not carry newer brand-name drugs. Medicare Part D fills this gap, but formularies vary by plan. AI/AN beneficiaries should compare Part D formularies against medications they're currently taking or likely to need, especially for chronic conditions like diabetes (which affects AI/AN populations at higher rates than the general population).

Coordination of Benefits: How IHS and Medicare Work Together

When an AI/AN Medicare beneficiary receives care at an IHS facility, Medicare becomes the primary payer and IHS becomes secondary. This means Medicare pays first according to its standard rules, and IHS covers remaining costs. For most services at IHS facilities, this arrangement eliminates out-of-pocket costs for the patient while bringing Medicare dollars into the IHS system.

The coordination works differently for different types of care:

Inpatient Hospital Care: Medicare Part A pays according to its benefit structure (no cost for days 1-60 after the $1,676 deductible), and IHS covers the deductible and any coinsurance. The patient pays nothing, and the IHS facility receives both Medicare reimbursement and credit for providing the uncovered portions.

Outpatient Services: Medicare Part B pays 80% after the $257 deductible, and IHS covers the deductible and 20% coinsurance. Again, no patient cost, but the IHS facility benefits from Medicare reimbursement.

Prescription Drugs: If the medication is available at the IHS pharmacy, there's typically no cost to the patient regardless of Medicare Part D coverage. If the medication isn't available through IHS, Part D coverage applies with standard copays and deductibles.

The Special Enrollment Rights That Matter

AI/AN people have special enrollment rights that can save significant money over time. Beyond the late enrollment penalty exemptions, these rights include:

Special Enrollment Period (SEP) for Medicare Advantage: AI/AN people can enroll in, disenroll from, or switch Medicare Advantage plans once per month. This flexibility allows for adjusting coverage based on changing health needs or moving between areas with different provider networks.

Employer Group Health Plan Coordination: For AI/AN elders who are still working or have employer coverage through a spouse, the coordination with IHS creates a three-way benefits structure. Employer coverage typically pays first, Medicare second, and IHS third — maximizing coverage while minimizing costs.

Bottom Line: Both Systems Need Each Other

The relationship between IHS and Medicare isn't competition — it's cooperation born of necessity. IHS provides culturally appropriate care and fills Medicare gaps (dental, vision, transportation) while Medicare brings additional federal dollars into IHS facilities and provides access to specialists when IHS resources are stretched thin.

For AI/AN elders, the decision isn't whether to choose IHS or Medicare. It's whether to maximize the benefit of both systems working together. The numbers support enrollment: Medicare reimbursements help fund IHS facilities that serve entire communities, not just Medicare beneficiaries. The $185 monthly Part B premium becomes an investment in community health infrastructure.

The system isn't perfect — Congress still funds IHS at 60% of need, PRC still runs out of money, and rural areas still face provider shortages. But the combination of IHS and Medicare creates more comprehensive coverage than either system provides alone. For a population that gave up 500 million acres for these treaty obligations, using every available federal health benefit isn't just smart — it's claiming what was promised.