Medicare enrollment happens during specific windows, and missing them can cost you thousands in penalties

You can sign up for Medicare during your Initial Enrollment Period, which is a seven-month window that starts three months before the month you turn 65 and ends three months after. If you sign up during the first three months (before your birthday month), coverage starts the month you turn 65. If you sign up in your birthday month or the three months after, coverage starts the first day of the following month. Missing this window means you pay a permanent penalty on your Part B and Part D premiums for as long as you have Medicare—even if you sign up years later.

You also have chances to sign up outside your Initial Enrollment Period if you have what Medicare calls a may have access to life event—losing employer coverage, moving to a new state, getting married or divorced, or having a significant change in income. These events open a Special Enrollment Period lasting 60 days from the date the event happens. Without a may have access to event, your next chance is the General Enrollment Period, which runs January 1 through March 31 each year, but this route still carries penalties if you missed your Initial Enrollment Period.

Key Takeaways

  • Your Initial Enrollment Period is seven months long: three months before you turn 65, the month you turn 65, and three months after—sign up during the first three months to avoid a gap in coverage.
  • Signing up late outside your Initial Enrollment Period triggers a permanent 10 percent penalty on Part B premiums and a 1 percent penalty per month on Part D premiums that you pay for life.
  • A may have access to life event like losing employer coverage or moving states opens a 60-day Special Enrollment Period where you can sign up without penalty.
  • The General Enrollment Period (January 1 through March 31) is always available but does not erase penalties from missing your Initial Enrollment Period.
  • If you are still working and covered by employer insurance at 65, you may be able to delay Medicare without penalty—ask your employer's benefits office whether you may have access to.

Your Initial Enrollment Period: The Seven-Month Window

The seven-month Initial Enrollment Period is your main chance to sign up for Medicare without penalties. It begins three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, your period runs from March through September.

Timing matters within this window. If you sign up between three months before your birthday month and the end of your birthday month, coverage starts the month you turn 65. If you sign up in the three months after your birthday month, coverage starts the first day of the following month. This gap can leave you uninsured, so signing up early is safer than waiting.

You sign up through Medicare.gov, by calling 1-800-MEDICARE, or by visiting your local Social Security office. Have your Social Security number and information about any current health or drug coverage ready. The process takes about 10 minutes online.

What Happens If You Miss Your Initial Enrollment Period

Missing your Initial Enrollment Period triggers a permanent penalty on Part B (medical insurance) and Part D (drug coverage). The Part B penalty is 10 percent of the standard premium for each full year you were may be able to access but not enrolled. If the standard Part B premium is $165 per month and you were may be able to access for three years without signing up, you pay an extra $49.50 per month for life. That adds up to $5,940 over ten years.

Part D carries a 1 percent penalty per month for each month you were may be able to access but not enrolled. If you were may be able to access for 36 months without signing up, you pay 36 percent more on your drug premiums forever. These penalties do not go away if you sign up later—they follow you as long as you have Medicare.

The only exception is if you had creditable coverage (health insurance through an employer, union, or government program) that was as good as or better than Medicare. If you can prove you had such coverage, you may avoid the penalty. You will need documentation from your former employer or plan showing the coverage dates and that it was creditable.

Special Enrollment Periods for Life Changes

A may have access to life event opens a Special Enrollment Period lasting 60 days from the date the event occurs. may have access to events include losing employer-sponsored health coverage, moving to a new state, getting married or divorced, becoming a U.S. citizen or permanent resident, or having a significant drop in income. If your employer laid you off or cut your hours, that counts. If you move from one state to another, that counts. If your spouse's employer coverage ends, that counts.

During a Special Enrollment Period, you can sign up for Medicare without the late penalties, even if you are past your Initial Enrollment Period. You must sign up within 60 days of the event. If you wait longer, you lose this protection and go back to the penalty rules. Keep documentation of the event—a termination letter, a lease showing your move date, a divorce decree, or a benefits letter showing income changes.

To report a may have access to event, call 1-800-MEDICARE or visit Medicare.gov and select "Report a Life-Changing Event." Have the date of the event and details about what happened ready.

The General Enrollment Period and Its Limits

The General Enrollment Period runs January 1 through March 31 every year. You can sign up for Medicare during this window even if you missed your Initial Enrollment Period and have no may have access to life event. However, this route does not erase the late penalties. If you sign up during the General Enrollment Period in March after missing your Initial Enrollment Period, you still owe the permanent Part B and Part D penalties.

Coverage through the General Enrollment Period starts July 1 of that year. This means if you sign up in January, you have a six-month gap with no Medicare coverage. If you sign up in March, you have a four-month gap. This gap can be expensive if you need medical care or prescriptions.

The General Enrollment Period is a safety net, not a preferred route. It exists mainly for people who genuinely did not know about Medicare or had circumstances that prevented them from signing up earlier. If you are approaching 65, your Initial Enrollment Period is always the better choice.

If You Are Still Working at 65

If you are still working and covered by your employer's health plan at 65, you may be able to delay Medicare Part B without penalty. This is called the Special Enrollment Period for working past 65. You must have health coverage through your current employer (or your spouse's current employer) based on active employment. Retiree coverage does not count.

To use this protection, you must sign up for Part A (hospital insurance) during your Initial Enrollment Period, but you can delay Part B until you leave your job or lose the employer coverage, whichever comes first. Once you lose coverage, you have eight months to sign up for Part B without penalty. You still need to sign up for Part A on time—missing that important date also carries a penalty, though it is smaller than the Part B penalty.

Ask your employer's benefits office whether your plan qualifies. They can tell you whether you are covered under the working-past-65 rules. If you are unsure, call 1-800-MEDICARE and describe your situation—they can confirm whether you can delay Part B safely.

How to Sign Up During Your Enrollment Period

You have three ways to sign up: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. Online is fastest—you can complete it in about 10 minutes if you have your information ready.

Gather your Social Security number, date of birth, and information about any current health or drug coverage before you start. If you are signing up for Part D (drug coverage), have a list of your current medications ready so you can compare plans. If you are signing up during a Special Enrollment Period, have documentation of the may have access to event available to upload or mail.

After you sign up, Medicare sends you a Medicare card in the mail within two weeks. Your coverage starts on the date Medicare confirms, which depends on when you signed up within your enrollment period. Do not wait for the card to arrive to start using your coverage—the coverage date is what matters, not the card arrival date.

Frequently Asked Questions

What if I turn 65 but am not a U.S. citizen yet?

You must be a U.S. citizen or permanent resident to sign up for Medicare. If you are not yet a permanent resident, you cannot enroll. Once you become a permanent resident, you have a Special Enrollment Period of 60 days to sign up without penalty, even if you are past your Initial Enrollment Period.

Can I change my mind after I sign up for Medicare?

Yes, but only during specific windows. You have until the end of the calendar year to change your Part D drug plan or switch between Medicare Advantage and Original Medicare plans. Outside these windows, you are locked into your choices until the next annual enrollment period (October 15 through December 7).

Do I have to sign up for Part A and Part B at the same time?

No. You can sign up for Part A (hospital insurance) and delay Part B if you have employer coverage or meet other exceptions. However, if you do not sign up for Part A during your Initial Enrollment Period and do not have a may have access to reason to delay, you pay a 10 percent penalty on Part A premiums for life, just like Part B.

What counts as a may have access to life event for a Special Enrollment Period?

Losing employer health coverage, moving to a new state, getting married or divorced, becoming a U.S. citizen or permanent resident, and having a significant drop in income all may have access to. Retiring does not may have access to on its own—you must have lost the actual coverage. If you are unsure whether your situation qualifies, call 1-800-MEDICARE and describe what happened.

If I sign up late, when do the penalties end?

The penalties do not end. They stay on your premiums for as long as you have Medicare. This is why signing up on time during your Initial Enrollment Period matters so much—it saves you thousands of dollars over your lifetime.