Lesson 5 of 15
Enrolling in Medicare
Quick answer
Sign up through the Social Security Administration during your Initial Enrollment Period — the 7-month window that begins three months before your 65th birthday month. If you're already collecting Social Security, Part A and Part B enroll automatically.
Key takeaways
- Initial Enrollment Period (IEP) = 3 months before, the month of, and 3 months after your 65th birthday.
- Already on Social Security? You'll be auto-enrolled in Parts A and B effective the first day of your 65th-birthday month.
- Not on Social Security yet? You must actively sign up at ssa.gov/medicare/sign-up or by calling SSA.
- For TFL, enroll early in your IEP so Part B is active before TRICARE Prime/Select coverage ends.
Detailed explanation
The three ways to sign up
- Online: ssa.gov/medicare/sign-up (fastest)
- By phone: 1-800-772-1213 (Social Security)
- In person: at your local Social Security office (appointment recommended)
Timing windows
- Initial Enrollment Period (IEP): the 7-month window centered on your 65th birthday month.
- General Enrollment Period: January 1 – March 31 if you miss the IEP (coverage starts the month after enrollment, with possible penalty).
- Special Enrollment Period (SEP): available if you had qualifying employer coverage; TRICARE alone is not employer coverage for SEP purposes.
Critical for retired military
Enroll in both Part A and Part B during your IEP. The day Part B is active, TFL activates. Miss this window and you risk a gap in coverage, a permanent Part B late-enrollment penalty, and loss of TFL.
Frequently asked questions
Will TRICARE remind me to enroll in Medicare?
DHA sends notifications, but enrollment is your responsibility. Do not wait for a letter — start early in your IEP.
Do I need a Medigap plan?
No. TFL fills the Medigap role for you — that's the whole point of the benefit.
Official government resources
- Sign up for Medicare (SSA)— Social Security Administration
- Medicare & You Handbook (2026)— CMS
- TRICARE For Life Handbook (2026)— Defense Health Agency
Official Medicare and TRICARE publications are the definitive source. This page is an independent educational summary; always confirm specifics against the resources above.