Your Initial Enrollment Period
For most people, the Initial Enrollment Period is 7 months long: it starts 3 months before the month you turn 65, includes your birthday month, and ends 3 months after it. When your coverage starts depends on when you sign up.
- 3 months beforeCoverage usually starts your birthday month
- 2 months beforeCoverage usually starts your birthday month
- 1 month beforeCoverage usually starts your birthday month
- Birthday monthCoverage starts the month after you sign up
- 1 month afterCoverage starts the month after you sign up
- 2 months afterCoverage starts the month after you sign up
- 3 months afterCoverage starts the month after you sign up
- Sign up in the first 3 months, and in most cases your coverage starts the first day of your birthday month.
- Sign up in your birthday month or the 3 months after, and coverage starts the first day of the month after you sign up.
- Birthday on the 1st of the month? Everything moves one month earlier: your window starts 4 months before your birthday month and ends 2 months after it, and early sign-up coverage starts the first day of the month before your birthday month.
Example from Medicare: if you turn 65 on June 2, your window runs from March through September. If you turn 65 on June 1, it runs from February through August.
Automatic enrollment, or signing up yourself
Already getting Social Security or Railroad Retirement benefits?
You’ll get Part A and Part B automatically, starting the first day of the month you turn 65. Your Medicare card comes in the mail about 3 months before your 65th birthday.
If you don’t want Part B (for example, because you have coverage from a current job), you must say so before the start date on your card. If you do nothing, you keep Part B and its premium is taken from your benefit.
Not getting those benefits yet?
You need to sign up for Part A and Part B through Social Security at SSA.gov/medicare/sign-up. You can also contact Social Security 3 months before you turn 65 to set up an appointment.
Part A and Part B: what to decide
Part A (hospital insurance): you usually don’t pay a monthly premium for Part A if you or your spouse paid Medicare taxes while working for a certain amount of time. If you don’t qualify for premium-free Part A, you may be able to buy it.
Part B (medical insurance): has a monthly premium. If you or your spouse are still working and you have health coverage from that job, it might be to your advantage to delay Part B — see the next section.
You need both Part A and Part B to join a Medicare Advantage Plan, and Part A or Part B to join a Medicare drug plan.
Still working? Employer coverage and Part B
Who pays first
If you’re 65 or older with coverage from your or your spouse’s current job:
- Employer with 20 or more employees: the job’s plan pays first.
- Employer with fewer than 20 employees: Medicare pays first (unless the employer is part of a multi-employer plan with 20 or more employees in total).
Delaying Part B without a penalty
With coverage from current work, you can sign up for Part B any time you’re still covered, or during the 8 months after the job or the coverage ends — whichever comes first. You usually won’t pay a late penalty when you sign up this way.
Health Savings Account (HSA)
You can’t contribute to an HSA once you have Medicare. If you sign up after 65, premium-free Part A generally goes back up to 6 months (but no earlier than the first month you were eligible), so plan when to make your last HSA contribution.
These don’t count as coverage from current work
COBRA, retiree coverage, VA coverage, individual coverage (such as a Health Insurance Marketplace plan), and former-employer coverage through severance or a layoff. When COBRA ends, you generally don’t get a Special Enrollment Period for Medicare — the 8-month window starts when the job or job-based coverage ends, whether or not you take COBRA.
If you have a Marketplace plan, end it before your Medicare coverage starts to avoid an overlap.
Late enrollment penalties: the rules
Penalties are added to your monthly premium, and some last for as long as you have the coverage. Here is how each one works:
Part B
Your Part B premium may go up 10% for each full 12-month period you could have had Part B but didn’t sign up. You usually pay it for as long as you have Part B. Signing up during a Special Enrollment Period may avoid it.
Part D (drug coverage)
You may owe a penalty if, after your Initial Enrollment Period ends, you go 63 days or more in a row without Medicare drug coverage or other creditable drug coverage. It’s 1% of the “national base beneficiary premium” for each full month without coverage, and you generally pay it as long as you have Medicare drug coverage. People who get Extra Help don’t pay it.
Part A (if you have to buy it)
If you don’t qualify for premium-free Part A and don’t buy it when first eligible, your premium may go up 10%, for twice the number of years you could have had Part A but didn’t sign up.
Have drug coverage from a job or union, TRICARE, the VA, or the Indian Health Service? Your plan must tell you each year whether it’s “creditable” (counts like Medicare drug coverage). Keep those notices.
Medicare Supplement (Medigap) timing
Original Medicare doesn’t pay all of the cost for covered services. A Medicare Supplement Insurance (Medigap) policy can help pay some of the remaining costs, like copayments, coinsurance, and deductibles. Your Medigap Open Enrollment Period is the 6 months that begin the first month you have Part B and are 65 or older. After it ends, you may not be able to buy a Medigap policy, or it may cost more. If you delay Part B because of coverage from current work, this period doesn’t start until you get Part B.
California’s Birthday Rule (California only)
California’s Medicare Supplement Birthday Rule allows individuals who already have a Medicare Supplement policy to switch to another policy with equal or lesser benefits during an annual enrollment period of at least 60 days beginning on their birthday, without medical underwriting. Certain insurance carriers may offer additional enrollment flexibility. This is a California rule — other states have different requirements.
Your step-by-step checklist
Mark your 7-month window
Write down the 3 months before your birthday month, your birthday month, and the 3 months after.
Find out whether you’ll be enrolled automatically
If you already get Social Security or Railroad Retirement benefits, watch for your Medicare card about 3 months before your birthday.
Still working? Talk to your benefits administrator
Ask how many employees your employer has, how the plan works with Medicare, whether its drug coverage is creditable, and when to stop HSA contributions.
Sign up through Social Security if you need to
Signing up in the first 3 months of your window means coverage can start your birthday month.
List your doctors, prescriptions, and pharmacies
You’ll use this list to compare coverage options.
Choose how you’ll get your coverage
Original Medicare (with or without a Medigap policy and a Medicare drug plan), or a Medicare Advantage Plan.
Don’t go without drug coverage
Join Medicare drug coverage when you’re first eligible unless you have creditable coverage — and keep the notice that says so.
Want a Medigap policy? Apply during your 6-month Medigap Open Enrollment Period
Review your coverage every fall
Annual Enrollment runs October 15 – December 7. See our Annual Enrollment 2027 guide.
Free, personalized Medicare counseling is also available from California’s State Health Insurance Assistance Program, the Health Insurance Counseling & Advocacy Program (HICAP), at 1-800-434-0222.
Turning 65 questions
Will I be enrolled in Medicare automatically when I turn 65?
Only if you already get Social Security or Railroad Retirement Board benefits. Then you get Part A and Part B automatically, starting the first day of the month you turn 65, and your Medicare card arrives about 3 months before your birthday. If you don’t get those benefits yet, you need to sign up through Social Security.
Can I delay Part B if I’m still working?
If you or your spouse are still working and you have health coverage from that job, you may be able to delay Part B without a penalty. You can sign up any time you’re still covered, or within 8 months after the job or the coverage ends, whichever happens first. COBRA and retiree coverage don’t count as coverage from current work. Ask your benefits administrator how your plan works with Medicare.
What happens if I miss my Initial Enrollment Period?
If you don’t qualify for a Special Enrollment Period, you can sign up for Part B during the General Enrollment Period, January 1 to March 31 each year. Coverage starts the first day of the month after you sign up, and you may pay a late enrollment penalty for as long as you have Part B.
When can I buy a Medicare Supplement (Medigap) policy?
Your Medigap Open Enrollment Period is the 6 months that start the first month you have Part B and are 65 or older. After that, you may not be able to buy a Medigap policy, or it may cost more. In California — and only there — people who already have a Medigap policy also get an annual enrollment period of at least 60 days, beginning on their birthday, to switch to a policy with equal or lesser benefits without medical underwriting.
Turning 65 soon? Talk with a licensed agent
A licensed Boomers agent can walk you through your enrollment dates and the Medicare plans we represent in your area. There is no cost to you and no obligation to enroll.
Monday – Friday, 9 AM – 5 PM PT
Sources
Dates and rules on this page come from these official sources.