Tribal Health Care, IHS and Medicare in Oklahoma

Quick answers

Do I need Medicare if I use IHS or a tribal clinic?

Usually yes. IHS isn't health insurance, Purchased/Referred Care pays only after Medicare and other coverage, and Medicare's enrollment deadlines and Part B penalty apply to American Indians and Alaska Natives the same as everyone else.

Will Medicare change where I get care?

No. You can keep using your IHS, tribal or urban Indian health program. The program bills Medicare for covered care you get there.

Do I need a Part D plan?

Drug coverage through an IHS, tribal or urban Indian program counts as creditable coverage, so you won't owe a Part D late penalty if you join later. A Part D plan can help with prescriptions filled outside the Indian health system.

Is there a special Medicare enrollment period for tribal members?

No. CMS says Medicare has no special enrollment provisions for American Indians or Alaska Natives. The monthly special enrollment period you may have heard about applies to Marketplace plans, not Medicare.

Can I join a Medicare Advantage plan?

Yes, if you have Part A and Part B and live in the plan's service area. CMS advises asking your Indian health care provider first, because the clinic may not be in the plan's network.

Tribal nations and Indian health care in Oklahoma

Oklahoma is home to 38 federally recognized tribes headquartered in the state, according to the Oklahoma Department of Libraries, which also lists one Oklahoma-based tribe that is not federally recognized. Each nation is a sovereign government, and many run their own health systems.

Health care for American Indians and Alaska Natives in Oklahoma comes through what is often called the I/T/U system:

• IHS (Indian Health Service): the federal agency. Its Oklahoma City Area serves Oklahoma, Kansas and parts of Texas, with eight service units that include federally operated hospitals, clinics and smaller health stations.
• Tribal (T): health programs that tribes run themselves under agreements with IHS. IHS notes that many tribes in the Oklahoma City Area operate their own programs, from large hospitals to smaller preventive and behavioral health programs.
• Urban (U): urban Indian health programs. In Oklahoma, IHS lists the Oklahoma City Indian Clinic and the Indian Health Care Resource Center of Tulsa, both offering full outpatient care.

Some of the largest tribally operated health systems in the state include:

• Cherokee Nation Health Services, which describes itself as the largest tribally operated health system in the country, with 12 facilities including a hospital and outpatient health centers in northeast Oklahoma.
• Chickasaw Nation Department of Health, based in Ada, where it runs the Chickasaw Nation Medical Center.
• Choctaw Nation Health Services Authority, which runs a hospital in Talihina and nine outlying clinics across the Choctaw Nation reservation in southeastern Oklahoma.
• Muscogee Nation Department of Health, which serves the Muscogee (Creek) Nation's 11-county reservation and runs hospitals including Creek Nation Community Hospital in Okemah.

Eligibility rules for each program are set by IHS and by each tribe. Ask the clinic you use what you need to show to be seen there.

Why enroll in Medicare if you already use IHS or a tribal clinic?

CMS says plainly that IHS is not health insurance. It delivers care and funds tribal and urban programs, but it can't pay for everything, and its Purchased/Referred Care program has limited funds. Signing up for Medicare helps in three ways:

• You keep your clinic. CMS notes that you can still use your Indian health care provider after you get Medicare, and the provider bills Medicare for you.
• Your program gains resources. CMS's guide for tribal Medicare beneficiaries says enrolling benefits your tribal health program through increased resources to provide more services. When a clinic bills Medicare for your visit, its own budget stretches further.
• You're covered outside the Indian health system. Medicare can pay when you see a specialist, need a hospital far from home or get care that Purchased/Referred Care can't authorize.

Purchased/Referred Care is the payer of last resort

Purchased/Referred Care (PRC, formerly Contract Health Services) pays for care outside IHS and tribal facilities when your clinic refers you. Federal rules (42 CFR 136.61) make IHS the payer of last resort: PRC won't pay to the extent that Medicare, Medicaid, private insurance or a state program would pay, or would pay if you applied. IHS says you must apply for and use alternate resources such as Medicare Part A and Part B, and refusing to apply when you are likely eligible can mean PRC denies your care.

Other PRC rules to know:

• You generally must live in your tribe's PRC delivery area, which covers the reservation and the counties that border it.
• Care must be authorized based on a referral and IHS medical priorities.
• In an emergency, you or someone for you must notify the PRC program within 72 hours. IHS extends that to 30 days for elders and people with disabilities.

The Part B deadline and late penalty apply to you

CMS states that Medicare's dates and deadlines apply to all populations and that there are no special provisions for American Indians or Alaska Natives. Using IHS or a tribal clinic doesn't count as the kind of coverage that lets you delay Part B without a penalty.

• Your Initial Enrollment Period is the 7 months around your 65th birthday: the 3 months before, your birthday month and the 3 months after.
• If you miss it and don't have job-based coverage from current work, you can sign up only from January 1 to March 31 each year, with coverage starting the next month.
• The Part B late penalty is $10% of the standard premium for each full 12-month period you went without Part B, and you generally pay it for as long as you have Part B.

If the Part B premium is hard to afford, a Medicare Savings Program through SoonerCare may pay it. See Medicare Savings Programs in Oklahoma, the penalty calculator and Medicare enrollment periods.

Part D drug coverage and Indian health pharmacies

• No Part D penalty: drug coverage from an IHS, tribal or urban Indian program counts as creditable prescription drug coverage under federal rules (42 CFR 423.56). You won't owe a Part D late penalty if you join a plan later. Ask your provider for a letter showing creditable coverage.
• Your pharmacy stays the same: CMS says that if you get prescriptions through an Indian health pharmacy, you pay nothing there, and having Medicare doesn't affect your ability to get IHS, tribal or urban Indian services.
• Plans must offer contracts to Indian pharmacies: every Part D plan must offer a contract to all I/T/U pharmacies in its service area (42 CFR 423.120).
• IHS payments count toward your cap: what IHS, a tribe or an urban Indian organization pays for your covered Part D drugs counts toward your yearly out-of-pocket limit (42 CFR 423.100). For 2026, Part D out-of-pocket costs are capped at $2,100.

When you have a Part D plan, your Indian health pharmacy can bill the plan and use that money for services in your community. See Part D in Oklahoma.

Medicare Advantage and your Indian health care provider

You can join a Medicare Advantage plan if you have Part A and Part B and live in the plan's service area. CMS's guide for tribal Medicare beneficiaries warns that Indian health care providers may not be in a Medicare Advantage plan's network, and that plan members may be limited to network doctors and facilities. CMS advises you to contact your Indian health care provider before you enroll to make sure the plan works with it.

There is no Medicare Advantage enrollment period just for tribal members. You make changes during the usual windows, such as October 15 to December 7 each year and the Medicare Advantage Open Enrollment Period from January 1 to March 31. The monthly special enrollment period for members of federally recognized tribes applies to Health Insurance Marketplace plans, not to Medicare. See Medicare Advantage in Oklahoma and IHS vs. Medicare vs. tribal health plans.

What you pay at an Indian health facility

CMS says there are no deductibles, coinsurance or copayments for covered services you get directly from IHS, a tribal health program or an urban Indian health program, or through an authorized PRC referral. If you go to a Medicare provider outside the Indian health system on your own, you may owe Medicare's deductibles, coinsurance and copayments, unless a Medicare Savings Program or SoonerCare helps. CMS also notes that some tribes help members pay for Part D plans; ask your tribe's health benefits office.

SoonerCare for tribal members with Medicare

If your income and resources are limited, you may qualify for both Medicare and SoonerCare, Oklahoma's Medicaid program, run by the Oklahoma Health Care Authority (OHCA). Medicare pays first; SoonerCare can help with what Medicare doesn't cover, and Medicare Savings Programs can pay Medicare premiums. OHCA says American Indian and Alaska Native members are exempt from SoonerCare copays. CMS also notes that Medicaid estate recovery doesn't apply to certain Indian trust property and income. See SoonerCare and Medicare.

Steps to take before you turn 65

1. Talk to your clinic's benefits office. Many Indian health programs help patients apply for Medicare, Part D, Medicare Savings Programs and SoonerCare.
2. Sign up for Part A and Part B. Apply through Social Security at ssa.gov or 1-800-772-1213 during your Initial Enrollment Period. If you already get Social Security benefits, you are enrolled automatically.
3. Decide on drug coverage. Your Indian health pharmacy coverage is creditable, but a Part D plan can cover prescriptions filled elsewhere and brings payment to your pharmacy.
4. Check networks before choosing a plan. If you consider Medicare Advantage, ask your clinic whether it works with the plan. To compare Medicare plans from the companies they work with, you can request a call from a licensed insurance agent, or see plans for your ZIP code.

For general Medicare questions, call 1-800-MEDICARE (1-800-633-4227; TTY 1-877-486-2048). More answers are on our Medicare questions page.

Sources

• Oklahoma Department of Libraries — Tribal Nations in Oklahoma
• IHS — Oklahoma City Area
• IHS — Urban Indian Organizations, Oklahoma City Area
• IHS — Purchased/Referred Care: Alternate Resources
• IHS — Purchased/Referred Care: Eligibility, residency and notification
• eCFR — 42 CFR 136.61, Payor of last resort
• eCFR — 42 CFR 423.56, Creditable prescription drug coverage
• eCFR — 42 CFR 423.120, Access to I/T/U pharmacies
• eCFR — 42 CFR 423.100, Definition of incurred costs
• CMS — Important Dates for Health Insurance (American Indians and Alaska Natives)
• CMS — A Guide to Original Medicare and Medicare Advantage for Tribal Medicare Beneficiaries
• CMS — Important Facts about Medicare for American Indians and Alaska Natives
• CMS — Medicare Prescription Drug Plans for American Indians and Alaska Natives
• CMS — 10 Important Facts about IHS and Health Insurance
• Medicare.gov — Avoid late enrollment penalties
• Oklahoma Health Care Authority — American Indian/Alaska Native members (copay exemption)
• Cherokee Nation Health Services
• Chickasaw Nation Department of Health — Medicare Part D Prescription Plans
• Chickasaw Nation Department of Health — Ada South Campus (Chickasaw Nation Medical Center)
• Choctaw Nation Health Services Authority — About us
• Muscogee Nation Department of Health

Every question in this guide

• Can I use Medicare at a tribal clinic or IHS hospital in Oklahoma?
• Can Native Americans get help paying Medicare premiums in Oklahoma?
• Do Native Americans in Oklahoma need Medicare if they have IHS?
• Does Medicare Advantage work with IHS and tribal clinics in Oklahoma?
• Will I pay a Part B late penalty if I only use IHS or tribal health care?

Frequently asked questions

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