Medicare has three main times each year when you can sign up, and missing them can cost you money for the rest of your life

You can sign up for Medicare during Initial Enrollment Period (the three months before, the month of, and three months after your 65th birthday), during the General Enrollment Period (January 1 to March 31 each year), or during Special Enrollment Period if you may have access to for an exception. The time you choose matters because late sign-up penalties are permanent — they add to your premium every month you have Medicare, even after you turn 80.

If you wait past your Initial Enrollment Period without a valid reason, you will pay a penalty of 10 percent of the Part B premium for each full 12 months you were not signed up. That penalty stays with you. If you delay Part D (prescription drug coverage), you pay 1 percent of the national base beneficiary premium for each month you were late, also permanently.

Key Takeaways

  • Your Initial Enrollment Period is three months before your 65th birthday, your birth month, and three months after — a seven-month window that is your best time to sign up without penalties.
  • If you miss your Initial Enrollment Period and have no may have access to reason, you can sign up during General Enrollment (January 1 to March 31), but you will pay a permanent penalty on your Part B and Part D premiums.
  • You do not have to sign up at 65 if you are still working and covered by your employer's health plan — but you must sign up within eight months of leaving that job or losing that coverage to avoid penalties.
  • Special Enrollment Periods are available if you lose employer coverage, move out of your plan's service area, or experience other may have access to life events — these let you sign up outside the regular windows without penalty.
  • You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

Your Initial Enrollment Period: The seven-month window at 65

Your Initial Enrollment Period starts three months before the month you turn 65 and ends three months after. This is the only time you can sign up without a penalty, and it is the time most people should use. If your birthday is June 15, your Initial Enrollment Period runs from March 1 through September 30.

You can sign up anytime during those seven months. You do not have to wait until your birthday month. Many people sign up two or three months early so their coverage starts on the first day of their birthday month. Coverage that starts on the first of the month is simpler to track than coverage that starts mid-month.

If you sign up during your Initial Enrollment Period, you will not pay a late penalty, no matter which parts of Medicare you choose or how long you wait between signing up for Part A and signing up for Part B.

General Enrollment Period: January 1 to March 31 each year

If you miss your Initial Enrollment Period, you can sign up during General Enrollment, which runs January 1 through March 31 every year. Coverage begins July 1 of that year. This means if you sign up in January, you have a six-month gap with no Medicare coverage.

Anyone can sign up during General Enrollment, but if you sign up after your Initial Enrollment Period ends, you will pay a permanent penalty. The penalty is 10 percent of the Part B premium for each full 12 months you were not signed up. If you were supposed to sign up at 65 and did not sign up until age 68, you owe three years of penalties — 30 percent added to your Part B premium for life.

The same rule applies to Part D (prescription drug coverage). If you go without Part D coverage and then sign up later, you pay 1 percent of the national base beneficiary premium for each month you were late. These penalties do not go away.

When you do not have to sign up at 65

You do not have to sign up for Medicare at 65 if you are still working and your employer offers health insurance. You can stay on your employer plan and delay Medicare sign-up without penalty, as long as your employer has 20 or more employees. This is called creditable coverage, and it protects you from late penalties.

When you leave your job or lose your employer coverage, you have eight months to sign up for Medicare without penalty. This eight-month window is a Special Enrollment Period. If you sign up within those eight months, you will not pay a late penalty, even if you are past your Initial Enrollment Period.

Tell your employer's benefits office that you are leaving and ask them to document your coverage dates. You will need this proof when you sign up for Medicare. If your employer coverage ends on a specific date, count eight months from that date — that is your important date.

Special Enrollment Periods: Exceptions to the regular windows

A Special Enrollment Period lets you sign up outside the regular enrollment windows without a penalty. You may have access to if you lose health coverage, move out of your plan's service area, experience a may have access to life event like divorce or death of a spouse, or have other specific circumstances.

Losing employer coverage is the most common reason for a Special Enrollment Period. You have eight months from the date your coverage ends. Losing coverage from a spouse's employer plan, losing Medicaid, or losing COBRA coverage also starts an eight-month Special Enrollment Period.

If you move and your current Medicare plan no longer serves your new address, you can switch plans outside the regular enrollment period. If you are in a Medicare Advantage plan and your plan leaves the Medicare program, you have a Special Enrollment Period to pick a new plan.

To use a Special Enrollment Period, you must sign up within the allowed timeframe and provide proof of the may have access to event. Call 1-800-MEDICARE to ask whether your situation qualifies and what documents you need to bring.

How to sign up and what you need

You can 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 sign-up is usually fastest. You will need your Social Security number, proof of citizenship or legal residency, and information about any current health coverage.

If you are signing up during a Special Enrollment Period, have your proof of the may have access to event ready — a letter from your employer about your coverage end date, a notice from your health plan, or a divorce decree, for example. Medicare will ask for this before approving your sign-up.

Sign-up takes about 10 minutes online. You will choose which parts of Medicare you want (Part A, Part B, Part D) and whether you want Original Medicare or a Medicare Advantage plan. You do not have to decide everything at once — you can sign up for Part A and Part B now and add Part D later, as long as you are still within your enrollment period.

What happens if you miss all the important date

If you miss your Initial Enrollment Period and do not have a may have access to reason for a Special Enrollment Period, you can still sign up during the next General Enrollment Period (January 1 to March 31). But you will pay a permanent penalty on your Part B premium.

The penalty is calculated from the month you should have signed up. If you should have signed up at 65 and you sign up at 68, you owe 36 months of penalties at 10 percent per year — that is 30 percent added to your Part B premium forever. Even if you live to 95, you will still pay that extra amount every month.

For Part D, the penalty is 1 percent of the national base beneficiary premium per month late. If you go three years without Part D coverage, you owe 36 months of penalties. These penalties are permanent and do not expire.

Questions to ask your doctor or Social Security office

Before you sign up, ask your current doctor whether they accept Medicare. Ask whether your prescriptions are covered under the Part D plans available in your area. If you have a chronic condition, ask your doctor which Medicare plan would work best for your care.

If you are still working, ask your employer's benefits office for the exact date your health coverage ends and whether your plan is creditable coverage under Medicare rules. Ask them to give you this in writing.

Call 1-800-MEDICARE if you are not sure whether you may have access to for a Special Enrollment Period or if you think you have a valid reason for signing up late. They can tell you whether a penalty applies to your situation.

Frequently Asked Questions

What if I turn 65 in the middle of the month?

Your Initial Enrollment Period still runs three months before through three months after your birthday month. If you turn 65 on June 15, your period runs March 1 through September 30. You can sign up anytime in that window, and coverage can start on the first of any month during your enrollment period.

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

No. You can sign up for Part A and Part B separately, as long as you sign up for both during your Initial Enrollment Period or during a Special Enrollment Period. If you sign up for one part late, you will pay a penalty on that part, but not on the part you signed up for on time.

What if I am still working past 65 but my employer does not offer health insurance?

You should sign up for Medicare during your Initial Enrollment Period, even if you are still working. Working does not protect you from late penalties unless your employer offers a health plan. If you do not have employer coverage, sign up at 65 to avoid penalties.

Can I change my mind after I sign up?

Yes, but only during certain times. You can change your Medicare Advantage plan or your Part D plan during the Annual Enrollment Period (October 15 to December 7 each year). You can also change plans if you have a Special Enrollment Period. Changes made outside these windows do not take effect until the following January 1.

What if I do not know my exact birthday for Medicare purposes?

Call Social Security at 1-800-772-1213 to confirm the birthday they have on file. Medicare uses the birthday Social Security has recorded, not the one on your birth certificate if they differ. Confirm this before your Initial Enrollment Period starts so there is no confusion about your important date.