You must sign up during specific windows, or you will pay a penalty for every month you delay

Medicare enrollment is not open year-round. You have a seven-month window centered on your 65th birthday — three months before, the month you turn 65, and three months after. Miss this window and you enter a penalty system that lasts for life. If you delay signing up for Part B (medical insurance) or Part D (drug coverage), Medicare adds a surcharge to your premium each month you were not enrolled. The surcharge is 10 percent per year of delay for Part B and 1 percent per month for Part D.

The rules change if you are still working and covered by your employer's health plan. If your employer has 20 or more employees, you can delay Part B without penalty as long as you are actively employed and covered. You must sign up within eight months of leaving that job or losing the coverage, or the penalty kicks in. Part D has no employer exception — if you go without drug coverage for even one month, the penalty applies.

Most people turn 65 and become may be able to access on the first day of the month in which they turn 65, or the first day of the month after, depending on their birth date. Social Security will tell you your exact may be able to access date when you contact them.

Key Takeaways

  • 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 miss your initial window and do not have an employer health plan, you pay a permanent surcharge on Part B premiums (10 percent per year of delay) and Part D premiums (1 percent per month of delay).
  • If you are covered by an employer plan with 20 or more employees, you can delay Part B without penalty, but you must sign up within eight months of leaving that job.
  • Part D (drug coverage) has no employer exception — going without it for even one month triggers a lifetime penalty.
  • You can sign up through Social Security, Medicare.gov, or by calling 1-800-MEDICARE, and the process takes about 10 minutes.

Your seven-month initial enrollment window

The window opens three months before the month you turn 65. If you turn 65 on any day in June, your window opens on March 1. If you turn 65 on June 15, your window still opens on March 1 — Medicare counts by the month, not the day. The window closes three months after the month you turn 65, so a June birthday gives you a window that runs March 1 through September 30.

During this window, you can sign up for Part A (hospital insurance), Part B (medical insurance), Part D (drug coverage), or any combination. Part A is usually free if you or your spouse paid Medicare taxes for at least 10 years. Part B and Part D both have monthly premiums that vary by income and by plan.

You do not have to sign up for everything at once. You can sign up for Part A and Part B during your initial window and add Part D later, as long as you add it before the window closes. If you add Part D after the window closes, you pay the monthly surcharge for every month you were not enrolled.

What happens if you miss your initial window

If you do not sign up during your seven-month window, you enter the General Enrollment Period, which runs January 1 through March 31 each year. You can sign up then, but your coverage does not start until July 1 of that year. If you miss the January-March window, you must wait until the next January to try again.

More important: you now owe a surcharge. For Part B, Medicare adds 10 percent to your premium for each full year you delayed. If you were may be able to access in June 2024 and did not sign up until March 2026, you delayed for nearly two years — that is a 20 percent surcharge on your Part B premium for life. For Part D, the surcharge is 1 percent per month of delay, compounded annually. A one-year delay costs 12 percent more per month, forever.

The surcharge does not go away. Even if you sign up later and pay it for years, it stays on your record. The only exception is if you had creditable drug coverage (coverage as good as Medicare's) through an employer or union during the time you were not enrolled in Part D. You must prove this with a letter from your former employer or plan.

The employer coverage exception for Part B only

If you are still working at age 65 and your employer has 20 or more employees, and you are covered by the employer's health plan, you can turn down Part B without penalty. You do not have to sign up for Part B while you are still covered and working. This is called creditable coverage.

The moment you leave that job or lose the coverage, you have eight months to sign up for Part B. The eight-month clock starts the month after your coverage ends. If your coverage ends in September, your eight-month window runs October through May. Sign up by May 31 and you pay no surcharge. Sign up in June and you owe a 10 percent surcharge.

This exception does not explore to Part D. Even if you have drug coverage through your employer, if you go without Part D coverage for one month after you become may be able to access, you owe the 1 percent monthly surcharge. Some employer plans are creditable for Part D purposes, which means you can delay without penalty, but you must check with your employer's benefits office to confirm. Do not assume.

How to sign up during your enrollment window

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 the form in about 10 minutes if you have your Social Security number and information about any current health coverage.

By phone, a representative will walk you through the same questions. The wait time varies by time of day and season. Early morning and mid-week are usually shorter. In-person signup at Social Security takes longer but may be helpful if you have questions about your specific situation or need help with the form.

You will need: your Social Security number, your date of birth, your citizenship or immigration status, and information about any current health coverage (employer plan, TRICARE, VA coverage, or other insurance). If you are signing up for Part D, have a list of the medications you take, or at least the names of the drugs. This helps you choose a plan that covers them at the lowest cost.

After you sign up, Medicare sends you a confirmation letter with your Medicare number. Part A coverage usually starts the first day of the month you turn 65. Part B and Part D coverage start the first day of the month after you sign up, unless you sign up during your initial enrollment window, in which case they can start the first day of the month you turn 65.

Special enrollment periods if you miss your window

A few situations let you sign up outside your initial window without penalty. These are called Special Enrollment Periods. They include losing employer coverage, moving out of your plan's service area, getting married or divorced, or having a significant change in income. You have 60 days from the event to sign up.

If you are still working past 65 and covered by an employer plan, you have a Special Enrollment Period that lasts eight months after you leave that job or lose the coverage. This is the same eight-month window mentioned earlier for Part B — it applies to Part A and Part D as well if you did not sign up during your initial window.

To use a Special Enrollment Period, you must contact Medicare or Social Security and explain the event that qualifies you. You will need to provide proof — a letter from your employer, a divorce decree, a notice of move, or documentation of the income change. Without proof, Medicare will not recognize the Special Enrollment Period and you will owe the surcharge.

Frequently Asked Questions

What if I turn 65 but do not plan to retire yet?

You still become may be able to access for Medicare on your 65th birthday. If your employer has 20 or more employees and you are covered by their health plan, you can delay Part B without penalty. You must still sign up for Part A (it is usually free) and you must sign up for Part D within your initial window or pay a surcharge, unless your employer plan is creditable for drug coverage.

Can I sign up before my 65th birthday?

Yes. Your enrollment window opens three months before the month you turn 65. You can sign up as early as that date. Many people sign up two or three months before their birthday so coverage starts on their 65th birthday without a gap.

What if I was not born in the United States?

You can sign up for Medicare if you are a U.S. citizen or a lawful permanent resident who has lived in the United States for at least five years. When you sign up, you will need to provide proof of citizenship or immigration status. A green card, passport, or naturalization certificate works.

Do I have to sign up for Part D if I do not take any medications?

You are not required to sign up, but if you go without Part D coverage for even one month after you become may be able to access, you will owe a 1 percent monthly surcharge if you sign up later. If you are certain you will never need prescription drugs, you can skip it, but the surcharge is permanent if you change your mind.

What if I already receive Social Security before age 65?

Social Security will automatically sign you up for Part A and Part B the month you turn 65, unless you ask them not to. You will receive your Medicare card in the mail about two weeks before your coverage starts. You still need to sign up for Part D separately if you want drug coverage, or you will owe the surcharge.