When should I sign up for Medicare?

Rules checked October 18, 2026, against medicare.gov, ssa.gov and cms.gov

Part A and Part B in brief

• Part A (hospital insurance) covers inpatient hospital stays and some skilled nursing care. It is premium-free if you or your spouse paid Medicare taxes for at least 10 years.
• Part B (medical insurance) covers doctor visits, outpatient care and tests. Almost everyone pays a monthly premium for it.
• Part D is prescription drug coverage, bought from private plans. Many retiree health plans include drug coverage that counts as "creditable," meaning it is at least as good as Part D.

The hard deadlines and penalties are mostly about Part B and Part D. Part A is usually free, so most people take it at 65 whatever else they do. (One exception: people with a health savings account must stop contributing to the HSA once enrolled in Medicare, and Medicare says to stop HSA contributions 6 months before you apply, because Part A coverage can start up to 6 months back (Medicare: Enrolling in Part A and Part B).)

Your initial enrollment period

Your initial enrollment period is 7 months long: the 3 months before the month you turn 65, the month you turn 65, and the 3 months after (Medicare: When can I sign up?). When your coverage starts depends on when you sign up (Medicare: When does coverage start?):

If you are already getting Social Security benefits before 65, you are enrolled in Part A and Part B automatically, starting the first day of the month you turn 65. Your card arrives in the mail about 3 months before your birthday. If you don't want Part B yet (for example, because you are still working), follow the instructions that come with the card.

Most public employees retire before 65 and wait to start Social Security, so they are not enrolled automatically. They need to apply themselves. Signing up for Medicare and starting Social Security are separate decisions.

If you are still working at 65

If you (or your spouse) are still working and covered by that employer's group health plan, you can usually wait to take Part B. When the job or the coverage ends, you get a special enrollment period of 8 months to sign up without a penalty. The 8 months start when you or your spouse stop working or when the job-based coverage ends, whichever happens first (Medicare: When can I sign up?).

Points to check:

• Employer size. If the employer has fewer than 20 employees, its plan may not pay for services unless you have both Part A and Part B. Ask the benefits office.
• Timing. To avoid a gap, Medicare suggests signing up for Part B the month before you plan to retire.
• Proof. You'll need your employer to confirm your coverage on form CMS-L564 (see "How to sign up" below).

Federal employees who keep working past 65 with FEHB are in this group. OPM says they can defer Part B until retirement and won't face a late penalty if they enroll during the special enrollment period; OPM also says to ask your employing office to complete form CMS-L564 when you retire (OPM: Active federal employees and Medicare).

The retiree coverage and COBRA trap

This is the most common and most expensive mistake for public retirees. Medicare is clear: "COBRA and retiree health plans aren't considered coverage based on current employment" (Medicare: Enrolling in Part A and Part B). That means:

• Retiree coverage from FEHB, Oregon PERS (PHIP), Washington PEBB, CalPERS or a school district does not give you a special enrollment period. If you skip Part B at 65 and later want it, you wait for general enrollment and pay the penalty.
• COBRA doesn't extend your deadline. Your 8-month special enrollment period starts when you stop working, even if you choose COBRA. Someone who retires at 64, takes 18 months of COBRA and signs up when COBRA ends may have missed both windows.
• Retiree plans often expect Medicare to pay first. Medicare warns that retiree coverage "may not pay" for your care if you don't have both Part A and Part B. Oregon's PERS Health Insurance Program requires all Medicare-eligible members and dependents to be enrolled in both Part A and Part B (Oregon PERS: PHIP).

Federal retirees with FEHB are not required to take Part B. But OPM notes that if you skip it during your initial enrollment period, you must wait for the next chance to enroll and you pay the late penalty for as long as you have Part B (OPM: Medicare for annuitants). Whether Part B is worth its premium alongside FEHB depends on your plan and your health.

Late penalties for Part B and Part D

Source: Medicare: Avoid late enrollment penalties. As an example, two years late on Part B means a 20% higher premium. If your retiree plan sends you a notice saying its drug coverage is creditable, keep it. It is your proof if you join Part D later.

How to sign up

Medicare enrollment for most people is handled by Social Security, not Medicare itself.

• During your initial enrollment period: apply online at ssa.gov, call 1-800-772-1213, or visit a Social Security office. You can apply for Medicare without starting Social Security retirement benefits.
• Part B only, if you already have Part A: use form CMS-40B. If you are using the special enrollment period after job-based coverage, also send form CMS-L564, which your employer fills out to confirm your coverage. You can fax or mail the forms, or apply online when you're leaving an employer plan (SSA: Sign up for Part B only).
• Part D or a Medicare Advantage plan: join through medicare.gov or the plan, or through your retiree program if it offers a Medicare plan.

What Part B costs in 2026 and 2027

For 2026, the standard Part B premium is $202.90 a month and the annual Part B deductible is $283. The Part A hospital deductible is $1,736 per benefit period (CMS: 2026 Medicare Parts A and B premiums and deductibles). People with higher incomes pay more; see our guide to IRMAA.

2027 premiums have not been announced yet. CMS usually announces them in the fall, often in November (the 2026 figures came out November 14, 2025). Social Security says people will see their 2027 Medicare premium in the my Social Security Message Center starting in late November 2026 (SSA: 2027 COLA announcement). We'll add the 2027 figures here when they are published.

What to do next

1. Mark your window. Count 3 months before your 65th birthday month. That is the earliest you can apply, and applying then avoids any gap.
2. Ask your retiree plan what it requires. Find out whether your PERS, PEBB, FEHB or district plan requires Part B and how it coordinates with Medicare.
3. Keep proof of coverage. Save employer coverage letters and creditable drug coverage notices.
4. Before 65, see our guide to health insurance before Medicare, and use our retirement checklist to keep the dates straight.

General information, not advice. We aren't part of Medicare, CMS or the Social Security Administration. For your own enrollment dates, call Social Security at 1-800-772-1213 or Medicare at 1-800-MEDICARE, and ask your retiree health plan how it works with Medicare.