When To Sign Up For Medicare: Deadlines and Enrollment Periods

Sign up for Medicare in the three months before you turn 65

Your Initial Enrollment Period starts three months before the month you turn 65 and ends three months after. This is the window when you can sign up without penalty. If you miss it, you will pay a permanent surcharge on your premiums for as long as you have Medicare — even if you sign up years later.

The surcharge is 10% per year you delayed. If you wait five years after you turn 65, you pay 50% more than the standard premium for Part B (doctor visits and outpatient care) and 80% more for Part D (prescription drugs). These penalties do not go away.

You do not have to wait until you turn 65 to start the process. You can call Social Security or visit Medicare.gov starting three months before your birthday month. The earlier you contact them, the more time you have to gather documents and ask questions.

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.
Missing this window costs you a permanent 10% surcharge per year delayed on Part B and Part D premiums.
If you are still working and have health coverage through your job, you may have a Special Enrollment Period that lets you delay without penalty.
You must enroll in Part A (hospital insurance) and Part B (doctor visits) separately from Part D (prescription drugs) — missing either important date triggers different penalties.
Contact Social Security or Medicare.gov three months before your 65th birthday to begin; do not wait until the last month.

What happens if you miss your Initial Enrollment Period

If you do not sign up during your seven-month window, you enter a General Enrollment Period that runs January 1 through March 31 each year. Coverage under this route starts July 1. This means if you miss your Initial Enrollment Period in June and do not sign up until February, you will have no Medicare coverage for eight months.

During those months without coverage, you are responsible for all medical costs. A hospital stay or emergency can cost tens of thousands of dollars. You cannot retroactively enroll to cover bills you already incurred.

The permanent premium surcharge applies whether you use the General Enrollment Period or sign up even later. There is no way to avoid it once you have missed your Initial Enrollment Period, except in narrow cases involving employer coverage or other government programs.

If you are still working at 65

If you have health coverage through your current job or your spouse's job, you may may have access to for a Special Enrollment Period that lets you delay Medicare without penalty. This applies only if your employer has 20 or more employees and you are actively working.

You must enroll in Part A (hospital insurance) within eight months of the date your employment ends or your coverage ends, whichever comes first. Part B (doctor visits) has the same eight-month window. If you miss this important date, the permanent surcharge applies.

Part D (prescription drugs) works differently. If you have creditable prescription drug coverage through your employer, you can delay Part D without penalty. But you must enroll within 63 days of losing that coverage. The eight-month rule does not explore to Part D — the important date is much shorter.

Enrolling in Part A versus Part B versus Part D

Medicare has three main parts, and each has its own enrollment important date and its own penalty for missing it. You must track all three separately.

Part A (hospital insurance) covers inpatient hospital stays, skilled nursing facilities, and hospice. Most people do not pay a premium for Part A because they or their spouse paid Medicare taxes while working. You should enroll in Part A during your Initial Enrollment Period even if you do not plan to use it yet, because there is no cost and no reason to delay.

Part B (doctor visits, outpatient care, and medical equipment) costs a monthly premium. The standard premium in 2024 is $164.90, but it changes each year and is higher if your income is above a certain threshold. Missing the Part B important date adds a 10% surcharge per year delayed.

Part D (prescription drugs) is sold by private insurance companies, not by Medicare directly. You choose a plan from a list. The important date is the same as Part A and Part B — your Initial Enrollment Period — but the surcharge is different: 1% of the national average Part D premium per month delayed. If you wait two years, you pay roughly 24% more per month forever.

How to sign up during your Initial Enrollment Period

You have three routes: online, by phone, or in person. Online is fastest.

Visit Medicare.gov and click "Sign up for Medicare." You will need your Social Security number, date of birth, and contact information. The site will ask whether you want Part A, Part B, and Part D. You can enroll in all three at once or choose different coverage. If you choose Part D, you will be directed to pick a prescription drug plan from the available options in your area.

By phone, call Social Security at 1-800-772-1213 (TTY 1-800-325-0778). They handle Part A and Part B enrollment. For Part D, Social Security will transfer you or give you the number for Medicare, which is 1-800-MEDICARE (1-800-633-4227).

In person, visit your local Social Security office. Bring your Social Security card, proof of citizenship or legal residency (passport, birth certificate, or naturalization papers), and proof of residence (utility bill, lease, or mortgage statement dated within the last two months). Processing in person takes longer than online but can be useful if you have questions.

Special cases: when you can enroll outside your Initial Enrollment Period

A Special Enrollment Period lets you sign up without penalty if certain events happen. These include losing employer coverage, moving out of your plan's service area, or becoming a U.S. citizen or permanent resident.

If you are a federal employee, you have a separate enrollment process through the Federal Employees Health Benefits Program (FEHB). You must coordinate your Medicare enrollment with your FEHB coverage to avoid gaps.

If you receive Supplemental Security Income (SSI) or Medicaid, you may have different rules. Contact your state Medicaid office or Social Security to confirm your enrollment window.

If you are not yet 65 but have been on Social Security Disability Insurance (SSDI) for 24 months, you become may be able to access for Medicare automatically. You do not need to sign up — Medicare starts the 25th month of your disability. You will receive a Medicare card in the mail. You still need to choose a Part D plan if you want prescription drug coverage.

What documents you need before you call

Gather these before you contact Social Security or Medicare:

Your Social Security number
Your date of birth
Your current mailing address and phone number
Information about any current health coverage (employer plan, Medicaid, Veterans benefits, or other insurance)
A list of your current doctors and hospitals, if you want to check whether they accept Medicare
A list of your current prescription drugs, if you are choosing a Part D plan

You do not need to have all of this to start the enrollment process, but having it ready speeds things up. If you are unsure whether your doctor accepts Medicare, you can look them up on Medicare.gov after you enroll.

Frequently Asked Questions

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

Your Initial Enrollment Period is still seven months long. It starts three months before the month you turn 65 and ends three months after. The exact day of your birthday within that month does not change the window. If you turn 65 on June 15, your period runs from March through September.

Can I change my mind after I enroll?

Yes, during your Initial Enrollment Period. You can change your Part D plan or switch between Original Medicare and Medicare Advantage until the end of your seven-month window. After that, you can only change plans during the annual Open Enrollment Period (October 15 through December 7 each year), and changes take effect January 1.

Do I have to enroll in Part B if I am still working?

If you have health coverage through your job and your employer has 20 or more employees, you can delay Part B without penalty. But you must enroll within eight months of losing that coverage. Part A (hospital insurance) is usually free and has no reason to delay. Part D (prescription drugs) has a shorter important date — 63 days after losing creditable coverage.

What if I do not know my exact birth date?

Contact Social Security before you turn 65. They have your official birth date on file. You will need to bring proof of birth (birth certificate, passport, or other government-issued ID) to confirm it. Resolving this before your enrollment period starts prevents delays.

Can I enroll in Medicare if I am not a U.S. citizen?

You must be a U.S. citizen or permanent resident (green card holder) to enroll in Medicare. If you are a permanent resident, bring your green card or other proof of permanent residency when you sign up. If you are not yet a permanent resident, you cannot enroll until you are.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.