Glossary
Medicare
The federal health insurance program for people 65+, certain younger people with disabilities, and people with ESRD or ALS.
Also known as: federal Medicare, Medicare program
Quick answer
Medicare is the U.S. federal health insurance program created in 1965 and administered by the Centers for Medicare & Medicaid Services (CMS). It has four parts: A (hospital), B (medical), C (Medicare Advantage), and D (prescription drugs). Most people qualify for premium-free Part A at 65 based on their (or a spouse's) Medicare-taxed work history.
Why it matters
For retired military, Medicare is not optional once you're eligible. The Defense Health Agency requires you to enroll in Medicare Parts A and B at 65 in order to keep TRICARE — which then converts to TRICARE For Life.
When you'll encounter it
Three months before your 65th birthday (the start of your Initial Enrollment Period). Also any time you experience a qualifying life event that triggers a Special Enrollment Period.
Impact on Medicare
Medicare is the program itself. Once enrolled, you choose between Original Medicare (Parts A + B, optionally + D) or Medicare Advantage (Part C).
Impact on TRICARE For Life
Without Medicare Parts A and B, TRICARE coverage ends at age 65 for Medicare-eligible beneficiaries. With them, you automatically transition to TRICARE For Life.
Impact on Medicare Advantage
You must be enrolled in Medicare Parts A and B before you can join a Medicare Advantage plan.
VA Healthcare considerations
Medicare and the VA are completely separate systems that do not share claims or coordinate benefits. You can be enrolled in both and use whichever is appropriate for the situation — VA for service-connected and rated conditions at VA facilities, Medicare (with TFL) for everything else. Enrolling in Medicare never reduces VA benefits or priority group.
Military-specific context
For retired military and their family members, Medicare enrollment at 65 is effectively mandatory because the Defense Health Agency requires Medicare Parts A and B to keep TRICARE coverage (which converts to TRICARE For Life). Skipping Medicare means losing TRICARE entirely.
Common misconceptions
- "Medicare is free." — Part A is premium-free for most. Part B has a standard monthly premium ($185 in 2025; higher with IRMAA). Deductibles and coinsurance apply.
- "Medicare covers everything." — It does not cover routine dental, vision, hearing aids, long-term custodial care, or most overseas care.
Common mistakes to avoid
- Confusing Medicare with Medicaid — Medicaid is a separate state-administered program for low-income individuals.
- Believing 'Medicare for All' or other proposals have changed how Medicare works today — they have not.
- Waiting until after the 65th birthday to start enrollment, missing the optimal IEP window.
Real-world scenario: A retired O-5 turns 65 next April.
She begins Medicare enrollment in January (3 months before her birthday month). Parts A and B activate April 1. DEERS receives her Medicare data within 30 days, and TRICARE For Life activates seamlessly — no gap in coverage.
Questions people commonly ask
- What is the difference between Medicare and Medicaid?
- Do I have to sign up for Medicare at 65?
- Can I have Medicare and VA Healthcare at the same time?
- What happens to my TRICARE when I turn 65?
Continue learning
— suggested by the knowledge graph- Appointment of RepresentativeA signed form (CMS-1696) that authorizes another person — family member, attorney, or advocate — to file or pursue a Medicare appeal on your behalf.
- Benefit Period (Part A)The Part A timeframe used to measure hospital deductibles and coinsurance — it resets after 60 days out of the hospital.
- Creditable CoverageNon-Medicare coverage that CMS deems at least as good as a standard Medicare Part D plan — TRICARE Pharmacy qualifies, so TFL beneficiaries don't need Part D.
- Creditable Drug CoveragePrescription drug coverage that CMS certifies is at least as good as standard Medicare Part D — including TRICARE Pharmacy and VA Pharmacy.
- Disability Medicare Eligibility (Under 65)Medicare eligibility before age 65 — automatic after 24 months of SSDI, immediately for ALS, and based on dialysis/transplant for ESRD.
- Durable Medical Equipment (DME)Medically necessary, reusable equipment for home use — covered by Part B at 80% after the deductible.
- End-Stage Renal Disease (ESRD)A condition (permanent kidney failure requiring dialysis or transplant) that grants Medicare eligibility at any age.
- General Enrollment Period (GEP)The January 1 – March 31 window each year when you can sign up for Medicare if you missed your IEP and don't qualify for an SEP.
- What is the Initial Enrollment Period (IEP)?The 7-month window around your 65th birthday — 3 months before, your birthday month, and 3 months after — when you first enroll in Medicare without penalty.
- I missed my Medicare enrollment window. Now what?Use the General Enrollment Period (Jan 1 – Mar 31). You'll likely owe a Part B late penalty for life, and you'll have no TFL until Part B is effective.
- How do I actually enroll in Medicare?Apply online at SSA.gov/medicare/sign-up, by calling SSA at 1-800-772-1213, or in person at a local SSA office. Online is fastest — most applications process in 1–2 weeks.
- Do I need Medicare Part A if I have TRICARE?Yes. TFL requires Part A and Part B. Part A is typically premium-free if you or your spouse worked 40+ quarters paying Medicare taxes.
- How long does Medicare enrollment take to process?Most online applications are approved in 1–3 weeks. SSA mails the Medicare card within about 30 days of approval.
Related lessons
Related glossary terms
Related Official Resources
Continue learning straight from the source. Every link below goes to an official government or DoD resource.
Last reviewed January 2026 against the 2026 Medicare & You and TRICARE For Life handbooks.