You can start the Medicare process process three months before the month you turn 65

Medicare enrollment opens on the first day of the month that is three months before your 65th birthday. If you turn 65 on any day in June, for example, your enrollment window opens on March 1. You do not have to wait until you turn 65 to begin — starting early gives you time to gather documents, compare plans, and avoid gaps in coverage.

The enrollment period lasts seven months total: three months before the month you turn 65, the month you turn 65, and three months after. During this time, you can enroll in Original Medicare (Part A and Part B), switch between Original Medicare and Medicare Advantage, or add prescription drug coverage (Part D). Missing this window can cost you in late-enrollment penalties that last for life, so understanding the exact dates matters.

Key Takeaways

  • Your Initial Enrollment Period opens three months before the month you turn 65 and closes three months after — a seven-month window total.
  • You can start gathering documents and comparing plans as soon as you know your 65th birthday month, even if enrollment has not yet opened.
  • Enrolling before your 65th birthday means coverage can start on the first day of the month you turn 65, with no gap.
  • If you miss your Initial Enrollment Period, you face permanent late-enrollment penalties on Part B and Part D unless you had creditable coverage through an employer.
  • You can enroll online through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

The three-month window before your 65th birthday

The three months before you turn 65 are when most people should enroll. If your birthday is in June, you can enroll starting March 1. Coverage will begin on June 1 — the first day of the month you turn 65 — as long as you enroll by March 31. This timing prevents any lapse between your current insurance and Medicare.

During these three months, you will need your Social Security number, proof of citizenship or legal residency, and information about any current health insurance. If you are still working and covered by an employer plan, bring details about that coverage — it may affect when you need to enroll in Part B without penalty. Have your doctor's name and any recent medical records handy if you are comparing Medicare Advantage plans, since some require medical underwriting.

What happens if you enroll after you turn 65

You can still enroll in the month you turn 65 and for three months after. If you turn 65 in June and did not enroll in March, April, or May, you can still enroll in June, July, August, or September. However, the coverage start date shifts. If you enroll in June (the month you turn 65), coverage starts July 1. If you enroll in July, coverage starts August 1. Each month you delay pushes your start date back another month.

This delay matters most if you have no other insurance. A gap between your current coverage and Medicare means you are uninsured, which can be costly if you need medical care. It also means you may face late-enrollment penalties on Part B and Part D that you will pay for the rest of your life — 10 percent more per year for each 12-month period you were late, for Part B, and a similar structure for Part D.

Late-enrollment penalties and exceptions

If you miss your seven-month Initial Enrollment Period and do not have a valid reason, you will owe a permanent penalty. For Part B, the penalty is 10 percent of the standard premium for each full 12-month period you were not enrolled. For Part D (prescription drug coverage), the penalty is 1 percent of the national base beneficiary premium for each month you were late. These penalties stay with you for life, even if you enroll years later.

Some people do not face penalties if they had creditable coverage — health insurance through a current employer, a spouse's employer, TRICARE, the Veterans Administration, or certain other sources. If you had creditable coverage and did not enroll during your Initial Enrollment Period, you have eight months after that coverage ends to enroll without penalty. Bring proof of that coverage when you enroll, such as a letter from your employer's benefits office or a copy of your insurance card.

How to prepare before your enrollment window opens

You do not have to wait for your enrollment period to start gathering information. Three to four months before you turn 65, visit Medicare.gov and create an account. You can browse plan options, read about coverage types, and see which doctors and hospitals are in each plan's network. This research takes time and is easier to do before the official enrollment period begins.

Collect your documents now: your Social Security number, birth certificate or passport, proof of citizenship (naturalization papers or a U.S. passport), and a list of all current medications with dosages. If you are still working, get a letter from your employer's benefits office stating whether your health plan is creditable coverage. If you are on COBRA or another continuation plan, get written confirmation of the coverage type and end date. Having these ready means you can enroll quickly once your window opens.

Enrollment methods and timelines

You can enroll through three main routes: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. Online enrollment is usually fastest — you can complete it in 15 to 20 minutes if your documents are ready. Phone enrollment takes longer because the representative will ask detailed questions, but it is useful if you have questions during the process. In-person enrollment at Social Security is an option if you prefer to speak with someone face-to-face.

Processing time varies. Online enrollment is often confirmed within one business day. Phone and in-person enrollment may take three to five business days. Plan to enroll at least two weeks before your desired coverage start date to allow time for processing. If you enroll on the last day of your Initial Enrollment Period, your coverage may not start until the following month.

Special situations: working past 65 or delaying enrollment

If you are still working at 65 and covered by your employer's health plan, you may not need to enroll in Part B right away. As long as your employer has 20 or more employees, you can delay Part B enrollment without penalty. However, you must still enroll in Part A (hospital insurance) at 65 — it is free and has no penalty for late enrollment. When you do leave your job or lose employer coverage, you have eight months to enroll in Part B without penalty.

Part D (prescription drug coverage) works differently. If you go without creditable drug coverage for even one month after your Initial Enrollment Period ends, you face a permanent penalty. If your employer plan covers drugs, get written confirmation that it is creditable coverage before you turn 65. If it is not, you must enroll in Part D during your Initial Enrollment Period even if you are still working.

Frequently Asked Questions

Can I enroll in Medicare before I turn 65?

You can start the enrollment process three months before the month you turn 65, but coverage cannot start before the first day of the month you turn 65. If you turn 65 on June 15, you can enroll starting March 1, but coverage will not begin until June 1.

What if I miss my Initial Enrollment Period?

You can still enroll during the General Enrollment Period (January 1 to March 31 each year), but you will face late-enrollment penalties on Part B and Part D that last for life. The only exception is if you had creditable coverage through an employer or other may have access to source — then you have eight months after that coverage ends to enroll without penalty.

Do I need to enroll in all parts of Medicare at the same time?

No. Part A (hospital insurance) and Part B (medical insurance) can be enrolled separately. Part D (prescription drug coverage) is separate from both. However, if you delay Part B or Part D past your Initial Enrollment Period without creditable coverage, you will owe permanent penalties.

What documents do I need to enroll?

You will need your Social Security number, proof of citizenship or legal residency (passport, naturalization papers, or birth certificate), and information about any current health insurance. If you are comparing Medicare Advantage plans, have your doctor's name and current medications ready.

Can I change my mind after I enroll?

Yes. You have until December 31 of the year you turn 65 to make changes to your Part A and Part B choices. For Medicare Advantage and Part D, you can make changes during the Annual Enrollment Period (October 15 to December 7 each year) or if you have a may have access to life event.