Why do Medicare enrollment periods matter?
Medicare is not open for changes all year long. You can only enroll or switch plans during set windows, and each window has its own rules. Miss the right one and you may wait months for coverage — or pay a late-enrollment penalty that never goes away.
The good news: once you see the year laid out on a calendar, the system makes sense. Here is a plain-words tour of every enrollment period, written for Los Angeles and Orange County seniors and the adult children who help them. Save this page — it is the kind of thing families look up every fall.
What is the Initial Enrollment Period (IEP)?
Your IEP is your first, personal window to join Medicare. It lasts seven months: the three months before your 65th-birthday month, your birthday month itself, and the three months after. It comes around only once, so it is worth preparing early.
If you already receive Social Security benefits, you are enrolled in Part A and Part B automatically. If not, you must apply yourself through Social Security. Missing the IEP can bring a Part B penalty of 10 percent for each full 12-month period you delayed — and that penalty lasts for life. The Part D drug-coverage penalty works differently: it adds up for each month you go without creditable drug coverage.
When is Medicare AEP, and what can I do during it?
The Annual Enrollment Period, or AEP, runs from October 15 through December 7 every year — the dates are the same in 2026 as in any other year. During AEP you can join, drop, or switch Medicare Advantage plans and Part D drug plans. Whatever you choose takes effect on January 1.
AEP is the busiest season of the Medicare year. It is the one window that applies to almost everyone on Medicare, which is why the fall mailbox fills up with plan advertisements. Put October 15 on your calendar now, the way you would a family birthday.
I like my plan. Do I really need to review it every year?
Yes — and this is the habit that protects you most. Plans change every year. A plan's doctor network, drug list, and costs for next year can all be different, even when the plan's name stays exactly the same. The plan that fit you well this year may fit differently next year.
In the fall, watch your mail for notices from your plan about next year's changes, and read them instead of tossing them. Then ask three questions: Are my doctors still in the network? Are my medications still covered? Did my costs change? If any answer worries you, AEP is your chance to adjust before the new year locks in.
What happens from January 1 to March 31?
Two different windows share these dates, and people often mix them up. The first is the Medicare Advantage Open Enrollment Period (MA OEP). It is only for people who are already on a Medicare Advantage plan and want to make a change after seeing how the new year actually started.
The second is the General Enrollment Period (GEP). This one is for people who missed their Initial Enrollment Period and still need to sign up for Medicare itself. With the GEP, coverage begins the month after you sign up. If this is your situation, do not wait for fall — the GEP exists so you can act in the new year.
What is a Special Enrollment Period (SEP)?
Life does not follow the Medicare calendar, and Special Enrollment Periods exist for exactly that reason. An SEP is a personal window that opens when certain life events happen to you, such as:
Each SEP has its own rules and time limits, so act quickly when your situation changes. If you are not sure whether an event gives you an SEP, ask before assuming you must wait for fall.
- You move to a new address — for example, from another state to Los Angeles
- You lose health coverage from an employer, or you retire
- Your Medi-Cal status changes
What does the whole Medicare year look like?
Here is the year at a glance, in plain words:
Your own IEP or an SEP can fall anywhere in the year, depending on your birthday and your life events. Everything else above repeats on the same schedule every year.
- January 1: Choices made during last fall's AEP take effect
- January 1 – March 31: MA OEP for people already on Medicare Advantage; GEP for those who missed their first window
- Spring and summer: The quiet season — a good time to organize records and check whether you qualify for Extra Help or Medi-Cal
- September: Plan mailings about next year's changes start to arrive — save them
- October 15 – December 7: AEP — review your coverage and change it if needed
- December 7: AEP closes; changes are locked in for January 1
How should I prepare for AEP in Los Angeles?
Official information is always available at Medicare.gov and by phone at 1-800-MEDICARE — both are government resources and good places to verify anything you hear. For a personal review in English or Korean, Rachel Park offers free consultations from her Downtown LA office near Koreatown.
Rachel is a licensed California agent (#0M85647) who has served Los Angeles and Orange County families since 2019, and a review with her is unhurried and thorough: your doctors checked against the network, your medications checked against the drug list, one by one. She works with multiple carrier partners, which means a review compares options rather than pushing one company. Call 213‑429‑0314 — before the fall rush, if you can.