Medicare Timing
Medicare Enrollment Periods, Made Easier to Follow.
Medicare uses several enrollment windows. The right one depends on whether you are new to Medicare, still working, changing plans, or experiencing a qualifying life event.
Medicare AEP Annual Enrollment Period Begins
Start with
Your situation
Different triggers open different windows.
Begin With This Distinction
Signing up for Medicare is not the same as choosing a plan.
Many enrollment questions become easier once you separate these two decisions.
1
Part A and Part B
Enrolling in Original Medicare
Social Security generally handles enrollment in Medicare Part A and Part B. If you receive Railroad Retirement Board benefits, the Railroad Retirement Board generally handles your Medicare enrollment.
- Initial Enrollment Period
- General Enrollment Period
- Certain Special Enrollment Periods
2
Coverage Choices
Joining or changing a Medicare plan
Medicare Advantage and Part D plans use their own enrollment windows.
- Initial Medicare Advantage or Part D enrollment opportunity
- Medicare Annual Enrollment Period (AEP)
- Medicare Advantage Open Enrollment Period
- Plan-related Special Enrollment Periods
Plain-language shortcut:
First determine when you can get Part A and Part B. Then determine when you can add, change, or leave private Medicare coverage.
Interactive Window Finder
Which situation sounds most like yours?
Select one option to see the enrollment window that may be most relevant.
Select your situation
Your likely enrollment window will appear here.
Choose one of the options to begin.This tool provides general guidance. Medicare makes the final determination based on your circumstances.
The Medicare Year
Some windows repeat every year. Others belong only to you.
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
General Enrollment Period
Part A / Part B sign-up
Jan 1–Mar 31
Medicare Advantage Open Enrollment Period
One change for current MA members
Jan 1–Mar 31
Medicare Annual Enrollment Period (AEP)
Review health and drug plans
Oct 15–Dec 7
Personal Enrollment Windows
Initial and Special Enrollment Periods
Based on your dates and circumstances
Recurring: Happens on fixed dates each year.
Personal: Begins because of your age, coverage, or life event.
Your First Medicare Window
The Initial Enrollment Period lasts seven months.
For most people qualifying at age 65, the window begins three months before the Medicare eligibility month, includes that month, and continues for three months afterward.
If your birthday is on the first day of a month, Medicare generally uses the previous month for age-65 enrollment timing.
Birthday Calculator
Enter your birthday to estimate your age-65 IEP.
Your dates will appear directly in the seven-month timeline below.
Estimated age-65 IEP
Enter your birthday to view your estimated dates.
Because your birthday is on the first day of the month, the calculator has shifted your Medicare eligibility month to the preceding month.
Month -3
Window opens
Enter birthday
Month -2
Enroll early
Enter birthday
Month -1
Confirm coverage
Enter birthday
Eligibility month
Age-65 Medicare month
Enter birthday
Month +1
Window continues
Enter birthday
Month +2
Window continues
Enter birthday
Month +3
Window closes
Enter birthday
Earlier enrollment can help prevent a delayed start.
If you sign up during the three months before your Medicare eligibility month, Part B generally begins that eligibility month. If you sign up during that month or during the following three months, coverage generally begins the month after you sign up.
This calculator provides a general estimate of the standard age-65 Initial Enrollment Period. It does not determine Medicare eligibility and does not account for disability, ALS, ESRD, employer coverage, automatic enrollment, or other special circumstances.
Working Past 65
Employer coverage can create more than one deadline.
Part B and private Medicare plan deadlines are not always the same length.
8
months
Part B Special Enrollment Period
Up to 8 months after current employment or qualifying job-based coverage ends
The 8-month clock generally begins when employment or coverage based on current employment ends, whichever happens first.
2
full months
Medicare Advantage or Part D plan window
Often shorter than the Part B window
After employer or union coverage ends, the plan-related Special Enrollment Period generally lasts for 2 full months after the month the coverage ends.
COBRA does not restart or extend the Part B enrollment clock.
The 8-month Part B Special Enrollment Period generally begins when current employment or coverage based on current employment ends, even if COBRA continues afterward.
Continue to COBRA and Medicare →Protect your prescription drug timeline.
After your Part D Initial Enrollment Period ends, going 63 continuous days or more without Medicare drug coverage or other creditable prescription drug coverage may result in a Part D late enrollment penalty.
What Each Window Is For
Similar dates can allow very different actions.
Initial Enrollment Period
Your first opportunity- Sign up for Part A and Part B
- Join Medicare Advantage
- Join a Part D drug plan
General Enrollment Period
A fallback for missed Part A or Part B enrollment- January 1 through March 31
- Coverage generally starts the next month
- Late penalties may apply
Medicare Annual Enrollment Period (AEP)
Review health and drug coverage for next year- October 15 through December 7
- Join, drop, or switch Medicare Advantage coverage
- Join, drop, or switch Part D coverage
Medicare Advantage Open Enrollment Period
One change during January 1 through March 31- Switch to another Medicare Advantage plan
- Return to Original Medicare
- Add Part D when returning to Original Medicare
Special Enrollment Period
Triggered by certain coverage or life changes- Moving outside a plan service area
- Losing employer or creditable coverage
- Changes involving Medicaid or Extra Help
A Different Kind of Window
The Medigap Open Enrollment Period is personal, one-time, and 6 months long.
Under federal law, it begins the first month you have Medicare Part B and are age 65 or older. It does not repeat every year.
California note: Current Medigap policyholders generally have a 60-day birthday period each year to apply for a Medigap policy with equal or lesser benefits without medical screening. Review California’s Birthday Rule.
Learn how Medicare Supplement works →
Your federal Medigap window
Six consecutive months, starting with your first qualifying month
Month 1
Part B is active and you are age 65 or older
End of month 6
Federal Medigap Open Enrollment Period ends
Month 1 is the first month both conditions are true. The federal window then runs continuously through month 6.
Deadline Clarity
Three assumptions that create avoidable problems.
Open each statement to reveal the clearer rule.
Assumption “The Annual Enrollment Period is when everyone signs up for Medicare.” Click to reveal the clearer rule
Clearer rule
The October 15–December 7 Medicare Annual Enrollment Period, also called AEP, is mainly for joining, changing, or leaving Medicare Advantage and Part D coverage. It is not the standard Part A and Part B sign-up period for someone approaching age 65.
Assumption “COBRA gives me more time to delay Part B.” Click to reveal the clearer rule
Clearer rule
COBRA generally does not extend the Part B Special Enrollment Period tied to current employment. The Part B clock usually begins when active employment or active-employment coverage ends.
Assumption “Every Medicare enrollment period lets me make the same change.” Click to reveal the clearer rule
Clearer rule
Each enrollment period controls a specific set of actions. Before submitting a change, confirm both the dates and what that period actually allows.
Verify Your Window
Official Medicare enrollment resources
Enrollment rights can depend on exact dates, employer status, coverage type, and the event that created your opportunity.
This page provides general educational information and does not determine whether you qualify for a particular enrollment or election period. It does not list every Special Enrollment Period or exception. Medicare, Social Security, the Railroad Retirement Board, and individual plans make final eligibility, enrollment, and effective-date determinations based on your circumstances. Confirm your dates before delaying coverage or submitting a plan change.