How to Enroll in Medicare When You Turn 65

You can enroll in Medicare starting three months before you turn 65

Medicare enrollment opens on the first day of the month you turn 65, but you can sign up as early as three months before that birthday. If you miss that window, you can still enroll during the General Enrollment Period from January 1 to March 31 each year, though you may face a permanent penalty on your premiums if you delay. The sooner you enroll after you become may be able to access, the sooner your coverage begins — usually the first day of the month you turn 65 or the month you sign up, whichever is later.

You do not have to wait until your birthday month to start the process. Many people find it easier to enroll a few months early when they have time to compare plans and gather documents. The Social Security Administration and Medicare.gov both let you start your enrollment online, by phone, or in person.

Key Takeaways

You can enroll in Medicare starting three months before you turn 65, and your coverage typically begins the first day of the month you turn 65.
You will need your Social Security number, birth date, citizenship or immigration status, and information about current health coverage when you enroll.
Social Security handles enrollment for people already receiving Social Security benefits; everyone else enrolls through Medicare.gov, by phone at 1-800-MEDICARE, or at a local Social Security office.
If you delay enrollment past your 65th birthday without a valid reason, you will pay a permanent 10 percent increase on your Part B premium for as long as you have Medicare.
You can change your Medicare plan once a year during the Annual Enrollment Period from October 15 to December 7.

What documents and information you need before you enroll

Gather your Social Security number, date of birth, and proof of U.S. citizenship or legal residency before you start. You will also need information about any current health insurance — including coverage through a spouse's employer, TRICARE (military coverage), or a Veterans Affairs plan. If you have current coverage, the enrollment system will ask when it ends so Medicare can coordinate with it.

Have your bank account information ready if you want your premium payments to come out automatically, though this is optional. If you are enrolling someone else (as a representative or family member), you will need a signed form authorizing you to act on their behalf.

Three ways to enroll: Social Security, Medicare.gov, or by phone

If you already receive Social Security retirement or disability benefits, Social Security will automatically enroll you in Medicare Part A and Part B about three months before your 65th birthday. You will receive a notice in the mail explaining your coverage and your options. You can accept this automatic enrollment, make changes to it, or decline Part B if you have other coverage.

If you do not receive Social Security benefits, you enroll directly through Medicare.gov, by calling 1-800-MEDICARE (1-800-633-4227), or by visiting your local Social Security office in person. Medicare.gov lets you compare plans side by side, see which doctors and pharmacies are in each plan's network, and check estimated costs for your prescriptions. The phone line and in-person offices can walk you through the same process if you prefer to talk to someone.

TTY users can call 1-877-486-2048. If English is not your first language, interpreters are available at no cost through all three enrollment channels.

Understanding the difference between Part A, Part B, and enrollment periods

Medicare Part A covers hospital stays, skilled nursing facility care, hospice, and some home health services. Part B covers doctor visits, outpatient care, lab tests, and medical equipment. Most people enroll in both at 65, though Part A is usually free if you or your spouse paid Medicare taxes for at least 10 years. Part B has a monthly premium that varies by income.

Your Initial Enrollment Period runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after. If you enroll during this window, your coverage begins on the first day of the month you turn 65 (or the first day of the month you enroll, if that is later). If you miss this period and do not have a valid reason — such as current employer coverage or membership in a federally recognized tribe — you can only enroll during the General Enrollment Period from January 1 to March 31, and your coverage will not start until July 1 of that year.

What happens if you delay enrollment

If you do not enroll in Part B during your Initial Enrollment Period and do not have a valid reason for the delay, Medicare will add a permanent 10 percent penalty to your Part B premium for each full 12-month period you were may be able to access but not enrolled. This penalty stays with you for life, even if you enroll later. For example, if you turn 65 in January 2024 but do not enroll until 2026, you will pay an extra 20 percent on your Part B premium forever.

The same penalty applies to Part D (prescription drug coverage) if you go without it for more than 63 days in a row. Valid reasons to delay without penalty include current employer coverage (yours or a spouse's), TRICARE, Veterans Affairs benefits, or membership in a federally recognized tribe. If you have one of these, you can enroll later without penalty, but you will need to show proof when you sign up.

Choosing between Original Medicare and Medicare Advantage plans

During enrollment, you will decide whether to use Original Medicare (Part A and Part B) or a Medicare Advantage plan (Part C). Original Medicare lets you see any doctor or hospital that accepts Medicare, and you pair it with a separate Part D plan for prescription drugs and a Medigap policy if you want help with copays and deductibles. Medicare Advantage plans bundle hospital, doctor, and usually prescription drug coverage into one plan, but they typically limit you to an in-network provider and may require referrals for specialists.

Neither choice is permanent. You can switch plans during the Annual Enrollment Period from October 15 to December 7 each year, and your new coverage begins January 1. If you enroll in a Medicare Advantage plan and change your mind within the first three months, you can switch back to Original Medicare without penalty.

What to do after you enroll

After you enroll, you will receive a Medicare card in the mail within two to four weeks. Keep this card and bring it to all doctor and hospital visits. Your coverage begins on the date shown in your enrollment confirmation — usually the first day of the month you turn 65 or the month you enroll, whichever is later.

If you enrolled in a Medicare Advantage or Part D plan, review the plan's formulary (list of covered drugs) and network (list of doctors and hospitals) to make sure your current providers are included. If your doctor or pharmacy is not in the network, contact the plan to ask about coverage options or consider switching plans during the next Annual Enrollment Period.

Frequently Asked Questions

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

If you or your spouse are still employed and have health insurance through that job, you can delay enrolling in Part B without penalty. You will still need to enroll in Part A (hospital insurance) at 65 unless you have a valid reason to delay. When you leave your job or lose that coverage, you have eight months to enroll in Part B without penalty.

What if I miss the enrollment important date?

You can still enroll during the General Enrollment Period from January 1 to March 31, but your coverage will not start until July 1. You may also owe a permanent penalty on your premiums. If you have a valid reason for missing the important date — such as employer coverage or a life event like losing a job — contact Medicare to ask about a Special Enrollment Period, which may let you enroll outside the normal windows.

Can I enroll in Medicare before I turn 65?

You can enroll starting three months before your 65th birthday, but your coverage will not begin until the first day of the month you turn 65 (or later if you enroll after that month). You cannot start Medicare coverage before you turn 65, even if you enroll early.

What if I am not a U.S. citizen?

You can enroll in Medicare if you are a lawful permanent resident (green card holder) and have lived in the United States for at least five years, or if you are a citizen. You will need to show proof of your immigration status when you enroll. Contact Medicare at 1-800-MEDICARE if you have questions about your specific situation.

How do I change my Medicare plan after I enroll?

You can change your plan once a year during the Annual Enrollment Period from October 15 to December 7. Your new coverage begins January 1. If you enroll in a Medicare Advantage plan and want to switch back to Original Medicare within three months, you can do so without waiting for the Annual Enrollment Period.

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.