You do not have to enroll in Medicare the month you turn 65, but waiting costs you money unless you meet specific exceptions.

If you delay past your 65th birthday without a valid reason, Medicare charges you a permanent penalty on your Part B (doctor visits) and Part D (prescription drugs) premiums. The penalty is 10 percent of the standard premium for each full 12 months you go without coverage. That penalty stays on your bill for life, even after you finally sign up. The only people who can delay without penalty are those still covered by an active employer health plan through their own job or a spouse's job.

Your initial enrollment window opens three months before the month you turn 65 and closes three months after. If you enroll during this window, coverage starts the first day of your birth month. If you miss it and have no employer coverage, you will pay the penalty when you do enroll, and your coverage will start the first day of the month after you sign up.

Key Takeaways

  • You can delay Medicare past 65 without penalty only if you or your spouse are still working and covered by that employer's health plan.
  • Missing your initial enrollment window and delaying without employer coverage triggers a permanent 10 percent monthly penalty on Part B and Part D premiums.
  • Your initial enrollment window is seven months long: three months before your 65th birthday, the month you turn 65, and three months after.
  • If you are retired or unemployed at 65, enrolling during your initial window costs less over your lifetime than delaying and paying the penalty later.
  • You must contact Social Security or Medicare directly to enroll; the process does not happen automatically even if you receive Social Security benefits.

When you can safely delay without a penalty

The only circumstance that lets you delay Medicare without penalty is active employer health coverage through your own job or your spouse's job. This means you or your spouse must still be working and the employer must still be offering health insurance. Retiree health plans do not count — only active employee coverage.

If you have employer coverage, you can work past 65 and delay Medicare. When you or your spouse finally leaves that job, you have eight months from the date coverage ends to enroll in Medicare without penalty. This eight-month window is separate from your initial enrollment window and gives you time to transition. You will need a letter from your employer or benefits administrator stating the date your coverage ended and confirming it was group health insurance.

If you are unsure whether your plan qualifies, contact your employer's benefits department or call Medicare at 1-800-MEDICARE to ask. Do not guess — the penalty is permanent if you guess wrong.

What happens if you miss your initial enrollment window

Your initial enrollment window is seven months total: the three months before you turn 65, the month of your birthday, and the three months after. If you do not enroll during this window and you have no employer coverage, you will face a late enrollment penalty when you do sign up.

The penalty applies to Part B (which covers doctor visits, outpatient care, and medical equipment) and Part D (which covers prescription drugs). For Part B, the penalty is 10 percent of the current standard premium for each full 12 months you delayed. If the standard Part B premium is $175 per month and you delayed two years, your penalty would be 20 percent, or $35 extra per month, added to your premium permanently. Part D penalties work the same way but are calculated differently for each drug plan.

You cannot remove this penalty by switching plans later. It follows you from plan to plan and lasts as long as you have Medicare. The only way to avoid it is to enroll during your initial window or prove you had employer coverage that may have access to you for the eight-month grace period.

How to enroll during your initial window

You have three ways to enroll: online through Medicare.gov, by phone with Social Security, or in person at a local Social Security office. The online route is fastest if you have your Social Security number and a Medicare number (if you have already received one in the mail).

To enroll online, go to Medicare.gov, sign in with your username and password, and select "Enroll in Medicare." You will answer questions about your coverage history and current health plan. The process takes about 15 minutes. You will receive a confirmation number when ready.

To enroll by phone, call Social Security at 1-800-772-1213 (TTY 1-800-325-0778). Have your Social Security number, date of birth, and citizenship information ready. Social Security staff will ask about your work history and any employer coverage. The call takes 10 to 15 minutes. You will receive a confirmation number and a follow-up letter in the mail.

If you prefer in-person enrollment, find your local Social Security office at ssa.gov/locator. Bring your Social Security card, proof of citizenship (passport, birth certificate, or naturalization papers), and proof of residence (utility bill or lease). Enrollment takes 20 to 30 minutes in person.

Part A versus Part B: which parts require enrollment

Part A (hospital insurance) is automatic for almost everyone. If you receive Social Security benefits or railroad retirement benefits, Part A starts the month you turn 65 without you doing anything. If you do not receive those benefits, you must enroll in Part A during your initial window or you will face a penalty.

Part B (doctor and outpatient care) is not automatic and requires you to enroll. Even if Part A started automatically, you must take a separate step to enroll in Part B. Many people miss this step and then face a penalty when they realize they are not covered for doctor visits.

When you enroll, you will be asked whether you want Part B to start the first day of your birth month or whether you want to delay it. If you have employer coverage, you can decline Part B during your initial window and enroll later without penalty, as long as you enroll within eight months of losing that coverage.

Costs of delaying versus enrolling on time

The financial case for enrolling during your initial window is strong for most people. Here is a concrete example: suppose you turn 65 in January 2025 and the standard Part B premium is $175 per month. If you enroll during your initial window (October 2024 through March 2025), you pay $175 per month starting January 2025.

If you delay and enroll in January 2026 (one year late) with no employer coverage, you will pay a 10 percent penalty: $17.50 extra per month, permanently. Over 20 years of Medicare, that is $4,200 in extra premiums you will never recover. If you delay two years, the penalty doubles to $35 per month, or $8,400 over 20 years.

The only scenario where delaying makes financial sense is if you have employer coverage that is genuinely better than Medicare and you will keep that coverage for several more years. In that case, delay and enroll within eight months of losing the job. Otherwise, enroll during your initial window.

What to do if you missed your initial window

If you missed your initial enrollment window and you have no employer coverage, you can still enroll, but you will pay the late penalty. Contact Social Security or Medicare to enroll as soon as you realize the mistake. The sooner you enroll, the sooner the penalty period ends and you stop accumulating additional penalties.

When you call or visit, be honest about when you turned 65 and why you did not enroll. Social Security and Medicare staff cannot waive the penalty, but they can confirm the exact amount and explain how it will appear on your bill. Some people may have access to for a Special Enrollment Period if they had a major life event (such as loss of employer coverage or moving to a new state), which can reset your enrollment window. Ask whether you may have access to.

Do not delay enrolling further hoping the penalty will go away. It will not. The sooner you enroll, the sooner you have coverage and the sooner you stop accumulating additional penalties.

Frequently Asked Questions

Does Social Security automatically sign me up for Medicare at 65?

Social Security automatically enrolls you in Part A (hospital insurance) if you are receiving Social Security retirement or disability benefits. Part B (doctor visits) is not automatic — you must enroll separately. If you are not receiving Social Security benefits, you must enroll in both Part A and Part B yourself during your initial window.

Can I delay Medicare if I have a private health plan from my employer?

Yes, if you are still working and your employer is offering that plan to active employees. Retiree plans do not count. When you leave the job, you have eight months to enroll in Medicare without penalty. Get a letter from your employer confirming the date your coverage ended.

What if I turn 65 but plan to keep working past 65?

If your employer still covers you as an active employee, you can delay Medicare without penalty. Enroll during your initial window anyway and decline Part B coverage, or wait and enroll within eight months of leaving the job. Do not skip enrollment entirely — you still need Part A.

How much is the late enrollment penalty exactly?

The penalty is 10 percent of the standard Part B premium for each full 12 months you delayed. The standard premium changes each year. If you delayed two years, your penalty is 20 percent of the current premium, added to your bill permanently. Part D (drugs) has a similar penalty calculated per plan.

Can I get the penalty removed if I enroll later?

No. The penalty is permanent and follows you from plan to plan for as long as you have Medicare. The only way to avoid it is to enroll during your initial window or prove you had may have access to employer coverage that gave you an eight-month grace period.