Medicare Enrollment Periods
You can't sign up for Medicare any time you want. There are set windows. Miss one and you may face a gap in coverage, a penalty, and missed opportunities.
Know your window already? Here is how to actually sign up, step by step.
The Windows at a Glance
Two pictures that cover most of it. The detail for every period is underneath.
Your Initial Enrollment Period
It is seven months long, not one. It opens three months before the month you turn 65 and closes three months after it.
Sign up in the three months before and your coverage starts the first day of your birthday month. Leave it until after and your start date slides.
Changing Plans After That
Two fixed blocks of the calendar. Outside them you need a qualifying life event to change anything.
- Open Enrollment, Oct 15 to Dec 7. Anyone on Medicare can switch. New coverage starts January 1.
- Advantage only, Jan 1 to Mar 31. If you are already in a Medicare Advantage plan you get one more move, and only one.
Miss both and you need a Special Enrollment Period, which takes a qualifying event: moving, losing other coverage, or becoming eligible for Medicaid or Extra Help.
When You First Get Medicare
These periods apply when you're first becoming eligible for Medicare.
Initial Enrollment Period (IEP)
Who: Anyone turning 65 or newly qualifying for Medicare due to disability.
What you can do: Enroll in Medicare Parts A and B; choose a Medicare Advantage plan or sign up for Medigap + Part D.
Special Enrollment Period, Working Past 65 (SEP)
Who: People who delayed Medicare because they had employer-sponsored health insurance (or coverage through a working spouse).
What you can do: Enroll in Medicare Part B without penalty. Must have had creditable employer coverage to qualify for this SEP.
Initial Coverage Election Period (ICEP), Medicare Advantage
Who: Anyone newly eligible for Medicare who wants to join a Medicare Advantage plan.
What you can do: Join a Medicare Advantage plan for the first time.
Annual Open Enrollment
These periods recur every year and allow most people to make plan changes.
Annual Enrollment Period (AEP), Open Enrollment
Who: Anyone currently enrolled in Medicare (Parts A and B).
What you can do: Switch between Medicare Advantage and Original Medicare; change Medicare Advantage plans; join, switch, or drop a Part D plan. Changes take effect January 1.
Medicare Advantage Open Enrollment Period (OEP)
Who: People currently enrolled in a Medicare Advantage plan.
What you can do: Switch to a different Medicare Advantage plan, or switch from Medicare Advantage back to Original Medicare (and join a Part D plan). Cannot use this period to switch from Original Medicare to Medicare Advantage.
Special Enrollment Periods (SEPs)
Life events can trigger a Special Enrollment Period outside the standard windows.
Dual-Eligible / D-SNP SEP
Who: People enrolled in both Medicare and Medicaid (dual-eligible).
What you can do: Switch to Original Medicare with a standalone Part D plan in any month, or enroll any month into an integrated D-SNP aligned with your Medicaid plan. (The former once-per-quarter SEP was replaced with monthly SEPs starting January 2025.)
Moving SEP
Who: People who move out of their plan's service area or to an area with new plan options.
What you can do: Switch plans when moving to a new service area.
Loss of Other Coverage SEP
Who: People who lose employer-sponsored, union, or other creditable coverage.
What you can do: Enroll in a Medicare Advantage or Part D plan.
Qualifying Event SEPs (Various)
Who: People who experience qualifying life events including: plan contract termination, moving into/out of long-term care, gaining/losing Medicaid, or plan sanction by CMS.
What you can do: Enroll in or switch Medicare coverage plans.
The Idaho Birthday Rule
Idaho is one of the few states with a birthday rule. If you have a Medigap plan, this is the one window each year when your health can't be held against you.
63 days, every year, starting on your birthday
Since March 2022, Idaho gives anyone with a Medicare Supplement plan a 63-day window that opens on their birthday. During those 63 days you can switch to a different Medigap plan, or keep the same plan and move to a different insurance company, and no one can turn you down or charge you more because of your health.
This matters because the same Medigap plan costs different amounts at different companies, and the benefits are identical by law. The birthday rule is your yearly chance to shop that price without a health review.
Idaho Medigap Birthday Rule
Who: Anyone in Idaho who already has a Medicare Supplement (Medigap) policy.
What you can do: Move to the same plan letter with another company, or to a plan with fewer benefits, without answering health questions.
One thing people miss: the window does not roll over and it is not automatic. If your birthday passes and you don't act within 63 days, you wait until next year. If you're on a Medigap plan, put a reminder on your calendar a month before your birthday, or just call us and we'll check your rate against the other companies for you.
Not Sure When You Can Make a Change?
Enrollment period rules are complex, and making a change at the wrong time can affect your coverage or trigger penalties. We'll tell you exactly what you can do and when, for free.
By calling you will be connected to a licensed insurance agent. Calls are recorded.
Ready to Find the Right Medicare Plan?
Medicare enrollment windows have strict deadlines. Speak with a licensed Idaho agent today, it's completely free.
Where these numbers come from
Every figure on this page comes from an official source, not from us. Check any of them yourself:
- 2026 Part A and Part B premiums, deductibles and coinsurance
- Medicare Part D and the out-of-pocket cap
- Enrollment periods and late enrollment penalties
- Extra Help and Medicare Savings Programs
- Idaho SHIP, free unbiased counseling
If anything here ever disagrees with Medicare.gov, Medicare.gov is right and we want to know about it. Call us at (208) 897-2228.