When and how to enroll in Medicare

You can enroll in Medicare during your Initial Enrollment Period, which runs for seven months — three months before the month you turn 65, the month itself, and three months after. You enroll through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office. Most people are enrolled automatically if they are already receiving Social Security benefits; if not, you must take action yourself or face a late-enrollment penalty.

If you miss your Initial Enrollment Period, you can enroll during the General Enrollment Period from January 1 to March 31 each year, though you will pay a higher monthly premium for Part B and Part D for as long as you have Medicare. The only exception is if you had creditable coverage (health insurance that meets Medicare's standards) through an employer or union — in that case, you may enroll without penalty during an eight-month window after that coverage ends.

The enrollment process itself takes about 10 minutes online. You will need your Social Security number, date of birth, and information about any current health coverage. Medicare will ask you to choose between Original Medicare (Part A and Part B) and a Medicare Advantage plan (Part C), and whether you want prescription drug coverage (Part D). Your coverage begins the first day of the month after you enroll, or on your 65th birthday if you enroll during 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 — and missing it triggers a permanent premium penalty.
  • If you already receive Social Security, Medicare will enroll you automatically; if not, you must enroll yourself through Medicare.gov, by phone, or at a Social Security office.
  • You must choose between Original Medicare (Part A and B) and Medicare Advantage (Part C), and decide whether to add prescription drug coverage (Part D).
  • Coverage begins the first day of the month after you enroll, or on your 65th birthday if you enroll during your Initial Enrollment Period.
  • If you miss your Initial Enrollment Period, you can enroll during General Enrollment (January 1 to March 31) each year, but you will pay higher premiums permanently.

What documents and information you need to enroll

Gather your Social Security number, date of birth, and citizenship or immigration status before you start. You will also need information about any current health coverage — the name of your employer or union, your group health plan number, or your spouse's coverage details if you are covered under their plan. If you are enrolling online, have your email address ready so Medicare can send you a confirmation.

If you are switching from employer coverage to Medicare, bring your coverage termination letter or the date your coverage ends. This document proves you had creditable coverage and protects you from late-enrollment penalties if you enroll within eight months of losing that coverage. If you cannot find the letter, call your former employer's benefits office and ask them to send it to you before you enroll.

The three ways to enroll

Online through Medicare.gov is the fastest route. Go to Medicare.gov/sign-up, create an account with your email and password, and answer questions about your age, citizenship, and current coverage. The system will show you plan options in your area, let you compare costs, and confirm your enrollment when ready. You will receive a confirmation email and your Medicare card will arrive by mail within two weeks.

By phone at 1-800-MEDICARE (1-800-633-4227) takes longer but works if you do not have internet access or prefer to speak with someone. Call between 8 a.m. and 8 p.m. Eastern time, seven days a week. A representative will walk you through the same questions as the online form, answer questions about plan choices, and submit your enrollment. You will still receive a confirmation by mail.

In person at your local Social Security office is an option if you need help or want to enroll face-to-face. Find your nearest office at ssa.gov/locator. Bring your Social Security number, proof of citizenship (passport, birth certificate, or naturalization papers), and information about current coverage. The office staff can answer questions about your options but cannot recommend a specific plan — that choice is yours.

Automatic enrollment if you receive Social Security

If you are already receiving Social Security retirement, survivor, or disability benefits when you turn 65, Medicare will enroll you automatically in Part A (hospital insurance) and Part B (medical insurance). You do not need to do anything. Medicare will mail you a card about three months before your 65th birthday showing your coverage details.

However, automatic enrollment does not include prescription drug coverage (Part D). You must enroll in Part D separately during your Initial Enrollment Period if you want it, or you will pay a late-enrollment penalty if you add it later. You also have the option to decline Part B if you have creditable coverage through an employer or union — to do this, contact Social Security before your coverage begins.

What happens if you enroll late

If you do not enroll during your Initial Enrollment Period and do not have creditable coverage, you will pay a late-enrollment penalty for as long as you have Medicare. For Part B, the penalty is 10 percent of the standard premium for each full year you were may be able to access but not enrolled. For Part D, the penalty is 1 percent of the national average premium for each month you were without coverage. These penalties are permanent — they do not go away after a certain time.

The only way to avoid the penalty is to show that you had creditable coverage (employer health insurance, union coverage, or TRICARE) during the time you were not enrolled in Medicare. You will need written proof from your former employer or plan. If you have this proof, contact Medicare at 1-800-MEDICARE and ask to have the penalty waived.

If you missed your Initial Enrollment Period but do not have creditable coverage, you can still enroll during the General Enrollment Period (January 1 to March 31 each year). Your coverage will begin July 1 of that year, and you will pay the late-enrollment penalty.

Choosing between Original Medicare and Medicare Advantage

During enrollment, you will choose between two paths. Original Medicare (Part A and Part B) is run by the federal government and covers hospital stays, doctor visits, and outpatient care. You can see any doctor or hospital that accepts Medicare. You will pay a monthly premium for Part B, a deductible when you use services, and coinsurance (a percentage of costs) after you meet the deductible. Most people add a Medigap policy to cover costs Original Medicare does not pay.

Medicare Advantage (Part C) is offered by private insurance companies approved by Medicare. These plans bundle Part A, Part B, and usually Part D (prescription drugs) into one plan. You typically pay a lower monthly premium than Original Medicare plus Medigap, but you must use doctors and hospitals in the plan's network (except in emergencies). Many plans include dental, vision, or hearing coverage that Original Medicare does not.

You do not have to choose right now. If you enroll in Original Medicare, you can switch to Medicare Advantage during the Annual Enrollment Period (October 15 to December 7 each year). If you enroll in Medicare Advantage, you can switch to Original Medicare during the same window, though you should enroll in a Medigap policy at the same time to avoid coverage gaps.

Adding prescription drug coverage

Prescription drug coverage (Part D) is optional but important. If you do not enroll in Part D when you first become may be able to access and later decide you want it, you will pay a late-enrollment penalty of 1 percent of the national average premium for each month you were without coverage. This penalty is permanent.

If you have creditable coverage through an employer, union, or retiree plan, you may not need to enroll in Part D right away — but you should verify that your coverage is creditable. Ask your plan administrator or call the plan directly. If your coverage ends, you have 63 days to enroll in Part D without a penalty.

During enrollment, you will see Part D plans available in your area. Plans vary in which drugs they cover, what you pay at the pharmacy, and which pharmacies you can use. Medicare.gov has a tool called "Find Care Providers and Suppliers" that lets you compare plans and see your out-of-pocket costs for your specific medications before you choose.

Frequently Asked Questions

Do I have to enroll in Medicare at 65 if I am still working?

If you or your spouse are still working and have employer health coverage, you can delay enrolling in Part B without penalty. You have eight months after your coverage ends to enroll without a late-enrollment penalty. However, you should still enroll in Part A (hospital insurance) at 65 because it is free and has no penalty for late enrollment. Contact Social Security to enroll in Part A only.

What 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, you must have lived in the United States for at least five years. Bring your green card or naturalization papers when you enroll. If you are not a citizen or permanent resident, you are not may be able to access for Medicare.

Can I change my plan after I enroll?

Yes. You can switch plans during the Annual Enrollment Period (October 15 to December 7 each year), and your new coverage begins January 1. If you have a may have access to life event — such as losing employer coverage, moving out of state, or getting married — you may be able to change plans outside the annual window. Call 1-800-MEDICARE to ask whether your situation qualifies.

What if I enroll online but do not receive my Medicare card?

Medicare cards arrive by mail within two weeks of enrollment. If you do not receive yours within three weeks, call 1-800-MEDICARE with your confirmation number (sent to your email) and they will reorder it. You can also create an account on Medicare.gov to view your coverage details while you wait for the physical card.

Do I need to enroll in all four parts of Medicare?

No. Part A (hospital insurance) is automatic if you receive Social Security, and you should enroll in it even if you are still working. Part B (medical insurance) is optional if you have creditable employer coverage. Part D (prescription drugs) is optional but carries a penalty if you delay. Part C (Medicare Advantage) is an alternative to Parts A and B, not an addition to them.