Every Medicare window — and which ones your program cares about
Medicare runs on windows: the 7-month Initial Enrollment Period around 65, the Jan 1–Mar 31 General Enrollment Period for latecomers, Oct 15–Dec 7 Annual Enrollment for plan changes, and Special Enrollment Periods — including the 8-month window after employer coverage ends and the creditable coverage SEP built for veterans' drug benefits.
The windows, in the order you'll meet them
| Window | When | What it does |
|---|---|---|
| Initial Enrollment Period (IEP) | 7 months around your 65th birthday (3 before, birthday month, 3 after) | First chance at Parts A, B, D, and MA. Enroll in the 3 months before for coverage starting your birthday month — the timing that keeps TFL seamless |
| Employer-coverage SEP | 8 months after employment or group coverage ends (whichever first) | Penalty-free Part B for those who delayed with creditable 20+-employee coverage |
| General Enrollment Period (GEP) | Jan 1 – Mar 31, yearly | The latecomer's door: Part B starts the month after you sign up, penalties attached |
| Annual Enrollment Period (AEP) | Oct 15 – Dec 7, yearly | Join, drop, or switch MA and Part D plans for Jan 1 |
| MA Open Enrollment (MA OEP) | Jan 1 – Mar 31, yearly | Current MA enrollees: one switch to another MA plan, or back to Original Medicare |
| Medigap Open Enrollment | 6 months from Part B's effective date at 65+ | Guaranteed-issue Supplement purchase — the window that never reopens |
| 5-star SEP | Dec 8 – Nov 30 | One switch into a 5-star-rated MA or Part D plan in your area, once per year |
| Creditable coverage SEP | Situational | The veteran-relevant one — full guide here |
Which windows your program cares about
- VA Healthcare only: the IEP is your Part B decision deadline — VA care doesn't pause it. Lose VA coverage someday and a 2-month SEP opens for Part D (63-day rule). AEP/OEP matter only if you hold MA or Part D.
- TRICARE for Life: the IEP (or employer SEP) is everything — Part B's start date is TFL's start date. After that, AEP matters only if you experiment with MA pairings.
- CHAMPVA: identical logic — Parts A & B on time, then the calendar mostly leaves you alone. Disability-based Medicare before 65 follows the same SEP/IEP rules.
- Everyone: moving counties, losing other coverage, plan exits, and similar life events each carry their own SEPs — when something changes, assume a window opened and check before it closes.
Three months before your 65th birthday. Acting in that window makes every other row of the table above either automatic or optional.
Timing questions are free to ask and expensive to guess. An agent can map your exact dates — IEP, employer SEP, Medigap window — in one conversation.
Connect With a Licensed AgentOr compare plans yourself at PlanMatch’s comparison tool, or contact Medicare.gov / 1-800-MEDICARE.
Frequently asked questions
When is the Medicare Initial Enrollment Period?
What happens if I miss my IEP?
Can I delay Medicare if I'm still working at 65?
When can I change Medicare Advantage plans?
You earned these benefits. Make them work together.
Whether you keep exactly what you have or add Medicare coverage alongside it, the right answer depends on your health, budget, and how you like to get care.
No cost, no obligation. You can also get help from Medicare.gov, 1-800-MEDICARE (TTY 1-877-486-2048), or your local SHIP office.