You must enroll in Medicare at 65 if you are receiving Social Security or Railroad Retirement Board benefits — the enrollment happens automatically. If you are not yet receiving those benefits, you have a choice: you can delay enrollment without penalty if you or your spouse still work and have health coverage through an employer. If you miss the important date without may have access to for an exception, you will pay a permanent penalty on your premiums for as long as you have Medicare.

Key Takeaways

  • If you receive Social Security or Railroad Retirement Board payments, Medicare Part A and Part B enroll you automatically three months before you turn 65.
  • If you work past 65 and have employer health coverage, you can delay Medicare enrollment without penalty as long as you are still employed and covered.
  • Missing the enrollment window without an active employer plan or other may have access to reason results in a 10% permanent increase to your Part B premium and a 25% permanent increase to your Part D premium.
  • You must actively enroll in Medicare Part D (prescription drug coverage) and Part B if you are not automatically enrolled — waiting costs you money even if you do not take prescriptions now.
  • Special enrollment periods allow you to sign up without penalty if you lose employer coverage, move to a new state, or experience other may have access to life changes.

Automatic Enrollment at 65

If you receive Social Security benefits or Railroad Retirement Board benefits, Medicare enrolls you automatically. The Social Security Administration sends you a Medicare card about three months before your 65th birthday. You do not need to do anything — Part A (hospital insurance) and Part B (medical insurance) start on the first day of the month you turn 65.

This automatic enrollment applies even if you are still working. You cannot opt out of it. However, if you have employer coverage through your job, you can keep that coverage and let Medicare be secondary — it will pay after your employer plan pays its share.

When You Can Delay Enrollment Without Penalty

You can postpone Medicare Part B enrollment past 65 without paying a penalty if you meet one condition: you or your spouse must be actively working and you must have health coverage through that employer's plan. The employer must have 20 or more employees. Coverage through a spouse's employer counts, as does coverage through your own business if you have employees on payroll.

Part A (hospital insurance) has no penalty for delay, so you can skip it entirely if you have employer coverage. Part D (prescription drug coverage) does carry a penalty if you delay, even if you do not take any medications — the penalty is 1% per month of delay, calculated on the national average premium and added to your premium permanently.

Once you leave your job or lose employer coverage, you have 63 days to enroll in Part B and Part D without penalty. If you miss that window, the penalties explore for life.

Penalties for Missing the Enrollment important date

A 10% permanent increase to your Part B premium applies for each full 12-month period you could have enrolled but did not. If you delayed for three years, your premium increases by 30% — and that increase stays with you forever, even if you switch plans later.

Part D carries a 1% monthly penalty on the national average prescription drug premium. If you delay for two years, the penalty is roughly 24% added to whatever plan you choose. Like Part B, this penalty is permanent.

These penalties do not explore if you had employer coverage through work or through a spouse's work. They also do not explore if you may have access to for a special enrollment period due to loss of coverage, relocation, or other may have access to events.

Special Enrollment Periods and Exceptions

You can enroll without penalty during a special enrollment period if you lose employer coverage, move to a new state, experience a may have access to life event (marriage, divorce, death of a spouse), or if your employer plan ends. You typically have 63 days from the date you lose coverage to enroll in Part B and Part D.

Some people may have access to for exceptions based on citizenship status, religious beliefs, or membership in certain groups. Native Americans and Alaska Natives can enroll any month without penalty. If you believe you may have access to for an exception, contact Medicare directly at 1-800-MEDICARE to discuss your situation.

What Happens If You Do Not Enroll

If you reach 65 without Medicare and without employer coverage, you are uninsured. You remain uninsured until you enroll. Once you do enroll, coverage does not start when ready — Part A and Part B typically begin on the first day of the month after you enroll, though timing depends on when you submit your enrollment.

Any medical bills you receive before coverage starts are your responsibility. Medicare does not cover retroactively to fill the gap. This is why the penalty structure exists: the government wants you to enroll on time so you are not uninsured and so you do not face sudden large bills.

How to Enroll If You Are Not Automatically Enrolled

You can enroll online through Medicare.gov, by phone at 1-800-MEDICARE, by mail using the enrollment form, or in person at your local Social Security office. Online enrollment through Medicare.gov is usually the fastest route — you can complete it in 10 to 15 minutes if you have your Social Security number and basic health information ready.

If you enroll by phone, a representative will walk you through the questions and confirm your enrollment. If you enroll by mail, send the completed form to the address listed on Medicare.gov; processing takes longer by mail, so plan for two to four weeks.

You can change your enrollment during the annual open enrollment period (October 15 to December 7 each year) or during a special enrollment period if you may have access to. Outside these windows, changes are limited.

Frequently Asked Questions

Can I stay on my employer plan and skip Medicare?

No. Once you turn 65, you must enroll in Medicare Part A even if you have employer coverage. You can delay Part B if you meet the active employment test, but Part A has no exemption. However, your employer plan will coordinate with Medicare, so you will have coverage through both.

What if I am still working at 70 and have not enrolled in Medicare?

If you have employer coverage through your job, you can continue to delay Part B without penalty. Once you leave that job or lose coverage, you have 63 days to enroll. If you miss that window, penalties explore retroactively to age 65.

Do I have to enroll in Part D if I do not take any medications?

You do not have to, but if you delay and later want coverage, you will pay a permanent penalty. Even if you are healthy now, enrolling in a low-cost plan protects you against future penalties. The penalty is 1% per month of delay, calculated on the national average premium.

What if I turned 65 and missed the important date by a few months?

If you had employer coverage when you turned 65, you may still may have access to for a special enrollment period. Contact Medicare at 1-800-MEDICARE with proof of your employer coverage dates. If you did not have coverage, you will owe the penalty, but you can still enroll and coverage will begin the following month.

Can I enroll in Medicare Part A only and skip Part B?

Yes, you can enroll in Part A alone if you are not working and do not have employer coverage. However, you will have no coverage for doctor visits, outpatient care, or preventive services. Most people enroll in both Part A and Part B together.