Medicare has three main enrollment windows each year, and missing them can cost you money

Medicare enrollment periods are the specific times of year when you can sign up for coverage, make changes to your plan, or switch between plans without penalty. There are three separate windows: Initial Enrollment Period (when you first become may be able to access), General Enrollment Period (a shorter window in early spring), and Annual Enrollment Period (the main window in fall). Missing these important date usually means you pay a higher premium for as long as you have Medicare, so knowing which period applies to you matters.

Your enrollment period depends on when you turn 65 or become may be able to access for Medicare through disability. The rules are strict — you cannot straightforward sign up whenever you want. Understanding which window applies to your situation helps you avoid late-enrollment penalties that can add hundreds of dollars to your monthly bill.

Key Takeaways

  • Your Initial Enrollment Period starts three months before the month you turn 65 and lasts for seven months total, giving you time to sign up before or after your birthday.
  • If you miss your Initial Enrollment Period, you can sign up during General Enrollment (January 1 to March 31 each year), but you will pay a penalty for each month you were late.
  • The Annual Enrollment Period (October 15 to December 7 each year) is when you can change plans, switch from Original Medicare to a Medicare Advantage plan, or add prescription drug coverage.
  • Late-enrollment penalties are permanent — they stay on your bill for life unless you have a Special Enrollment Period that removes them.
  • Special Enrollment Periods open outside the normal windows if you lose employer coverage, move, or experience certain life changes.

Your Initial Enrollment Period: The seven-month window when you first turn 65

Your Initial Enrollment Period begins three months before the month you turn 65 and ends three months after. This gives you a total of seven months to sign up. For example, if you turn 65 in June, your window opens in March and closes in September. You can sign up at any point during this period — you do not have to wait until your birthday month.

During this window, you sign up for Part A (hospital insurance) and Part B (medical insurance). You can also choose Original Medicare (Parts A and B) or a Medicare Advantage plan, and you can add Part D (prescription drug coverage) or a Medigap policy. The month you sign up does not affect your coverage start date — if you sign up anytime during your seven-month window, your coverage begins on the first day of the month you turn 65.

If you are still working and have health insurance through your employer, you may be able to delay signing up for Part B without penalty. This is called the Special Enrollment Period for people with group health plan coverage. You will need to provide proof of your employer coverage when you eventually sign up.

General Enrollment Period: The backup window in early spring

If you miss your Initial Enrollment Period, you can sign up during General Enrollment, which runs from January 1 to March 31 each year. Coverage begins July 1 of that year. This means there is a gap — if you sign up in January, you will not have Medicare coverage until July.

The major drawback of using General Enrollment is the late-enrollment penalty. For Part B, you pay an extra 10 percent of the standard premium for each full year you were may be able to access but not enrolled. This penalty is permanent — it stays on your bill for the rest of your life. For Part D (prescription drug coverage), the penalty is 1 percent of the national average premium per month of delay. These penalties add up quickly and are rarely waived.

General Enrollment is meant as a safety net, not a preferred route. If you realize you missed your Initial Enrollment Period, contact Medicare or visit Medicare.gov to understand the penalty amount before you sign up.

Annual Enrollment Period: The fall window for changing plans

The Annual Enrollment Period (also called Open Enrollment) runs from October 15 to December 7 each year. This is when you can change plans, even if you are already enrolled in Medicare. You can switch from Original Medicare to a Medicare Advantage plan, from Medicare Advantage back to Original Medicare, or change from one plan to another within the same category.

You can also use this window to add Part D (prescription drug coverage) if you do not have it, or to switch to a different Part D plan. Changes you make during Annual Enrollment take effect January 1 of the following year. If you do not make any changes, your current plan continues automatically.

This is the only time each year most people can make changes without a penalty or waiting period. If you are unhappy with your current plan, have a change in health needs, or want to compare costs, Annual Enrollment is when to act.

Special Enrollment Periods: When you can sign up outside the normal windows

Special Enrollment Periods open when you experience certain life events that affect your coverage. These include losing employer health insurance, moving to a new state, getting married or divorced, having a baby, or being released from prison. If you may have access to for a Special Enrollment Period, you can sign up for Medicare or change plans outside the normal windows without penalty.

You typically have 60 days from the event to sign up or make changes. For example, if you lose your job and your employer coverage ends on June 30, you have until August 29 to sign up for Medicare. The exact rules vary by situation, so contact Medicare at 1-800-MEDICARE to confirm whether your event qualifies and what documents you need.

Special Enrollment Periods can also remove late-enrollment penalties if you had a valid reason for missing your Initial Enrollment Period. For instance, if you did not sign up because you were still covered by your employer, you may not owe a penalty when you eventually enroll.

What happens if you miss all the enrollment periods

If you do not sign up during your Initial Enrollment Period and do not may have access to for a Special Enrollment Period, you must wait until the next General Enrollment Period (January 1 to March 31). During this wait, you will have no Medicare coverage unless you are still covered by an employer plan or other insurance.

When you finally sign up during General Enrollment, your coverage does not start until July 1. You will also owe a permanent late-enrollment penalty on your Part B and Part D premiums. The longer you wait, the larger the penalty becomes. For Part B, the penalty is 10 percent per year of delay. For Part D, it is 1 percent per month of delay.

These penalties are calculated from the time you first became may be able to access for Medicare, not from when you actually sign up. If you turned 65 in 2022 and did not sign up until 2024, you owe penalties for two full years of delay.

How to sign up during your enrollment period

You can sign up for Medicare in three ways: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. If you are already receiving Social Security benefits, you may be enrolled automatically in Parts A and B, but you should verify this by checking your Social Security account or calling Social Security.

When you sign up, have your Social Security number, birth date, and citizenship information ready. If you are choosing a specific plan (Medicare Advantage or Medigap), have the plan name and number available. The process usually takes 15 to 30 minutes by phone or online.

After you sign up, Medicare sends you a Medicare card in the mail within two weeks. Keep this card with you at all medical appointments. If you do not receive it, call Medicare to request a replacement.

Frequently Asked Questions

What if I turn 65 while still working?

You can delay signing up for Part B without penalty if you have health insurance through your current employer. You have eight months after your employment ends or your coverage stops to sign up for Part B without a late-enrollment penalty. You must still sign up for Part A (hospital insurance) during your Initial Enrollment Period.

Can I change my mind after I sign up during my enrollment period?

Yes, but only within certain limits. If you sign up for a plan and change your mind within the first few days, you can cancel and choose a different plan during the same enrollment period. After that, you must wait for the next Annual Enrollment Period to make changes, unless you may have access to for a Special Enrollment Period.

Do I have to sign up for Part D during my Initial Enrollment Period?

No, but if you do not have prescription drug coverage and sign up later, you will owe a permanent penalty of 1 percent of the national average premium for each month of delay. If you do not take any prescription drugs, you can delay without penalty, but you must sign up before you need it.

What if I move to a different state?

Moving to a new state qualifies you for a Special Enrollment Period. You have 60 days from your move to change plans if your current plan is not available in your new state. Contact Medicare to confirm your new plan options and important date.

How do I know which enrollment period I am in?

Call Medicare at 1-800-MEDICARE and provide your birth date. They will tell you whether you are in your Initial Enrollment Period, whether you have missed it, and what your options are. You can also check Medicare.gov and enter your information to see your enrollment status.