When You Can Start Medicare: Age Requirements and Enrollment Timing

You can enroll in Medicare starting at age 65, though some people under 65 with disabilities or end-stage renal disease may also be covered

Medicare enrollment opens three months before the month you turn 65. If your birthday is March 15, you can enroll starting December 1 of the previous year. The enrollment window stays open for three months after your birthday month — so you have a total of seven months to sign up without penalty.

If you miss this window, you will pay a permanent penalty on your Part B and Part D premiums for as long as you have Medicare. The penalty is 10 percent of the Part B premium for each full year you were may be able to access but did not enroll, and 1 percent of the Part D premium for each month you were without drug coverage. These penalties do not go away, even if you enroll years later.

Key Takeaways

You become may be able to access for Medicare at age 65, and enrollment opens three months before your 65th birthday.
You have seven months total to enroll without facing a permanent penalty on your premiums.
Some people under 65 with disabilities or end-stage renal disease can enroll in Medicare before reaching 65.
If you are still working and covered by your employer's health plan at 65, you may be able to delay enrollment without penalty.
You must actively enroll in Medicare; it does not happen automatically when you turn 65.

Enrollment periods and how they work

The Initial Enrollment Period (IEP) is your main window to sign up. It runs for seven months: three months before the month you turn 65, the month of your birthday, and three months after. If you turn 65 in June, your IEP is March through September. You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

If you miss your IEP, you can still enroll during the General Enrollment Period, which runs January 1 through March 31 each year. However, coverage does not start until July 1, and you will owe the permanent penalty described above. The only exception is if you had a may have access to life event — such as losing employer coverage or moving to a new state — which opens a Special Enrollment Period lasting eight months.

People under 65 who can enroll in Medicare

You do not have to wait until 65 if you have been receiving Social Security Disability Insurance (SSDI) for 24 months. You become may be able to access for Medicare automatically after those 24 months pass; you do not need to reapply. If you are on SSDI, contact Social Security to confirm your Medicare start date.

You can also enroll before 65 if you have end-stage renal disease (ESRD) — permanent kidney failure requiring dialysis or a transplant. may be able to access begins the first day of the month you start dialysis treatment or the month of your transplant. People with ALS (amyotrophic lateral sclerosis) become may be able to access for Medicare when ready upon receiving an SSDI award, without waiting the usual 24 months.

What happens if you are still working at 65

If you are covered by your employer's health plan when you turn 65, you may be able to delay enrolling in Part B without penalty. This is called the Special Enrollment Period for people with group health plan coverage. You must enroll within eight months of losing that coverage or retiring, whichever comes first.

However, you should still enroll in Part A (hospital insurance) at 65 even if you delay Part B, because Part A is usually free and has no penalty for late enrollment. Part D (prescription drug coverage) does carry a penalty if you delay, so check whether your employer plan covers drugs at least as well as Medicare does before deciding to wait.

How to enroll when you reach 65

You have three ways to enroll: 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 fastest — you can complete it in about 10 minutes if you have your Social Security number and birth date ready.

When you enroll, you will choose which parts of Medicare you want. Part A covers hospital stays, Part B covers doctor visits and outpatient care, Part D covers prescription drugs, and Medigap or Medicare Advantage are optional supplemental plans. You do not have to decide everything at once — you can enroll in Part A and B now and add Part D later, though waiting on Part D will trigger the monthly penalty mentioned above.

Penalties for late enrollment

The Part B penalty is 10 percent of the standard monthly premium for each full year you were may be able to access but did not enroll. If the standard Part B premium is $164.90 per month and you were may be able to access for three years without enrolling, your penalty would be 30 percent — meaning you would pay $214.37 per month instead of $164.90, permanently.

The Part D penalty is 1 percent of the national average drug plan premium for each month you were without coverage. As of 2024, that national average is around $34 per month, so one year of delay costs roughly $4 per month in penalty, permanently. These penalties explore even if you enroll years later, and they do not expire.

Frequently Asked Questions

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

You should enroll in Part A at 65 because it is usually free and has no penalty for delay. Part B enrollment can sometimes be delayed without penalty if you have employer coverage, but you must enroll within eight months of losing that coverage. Part D (drug coverage) does carry a penalty if you delay, so check your employer plan's drug coverage first.

What if I turn 65 and do not have health insurance?

Enroll in Medicare when ready during your Initial Enrollment Period. You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE, or at your local Social Security office. Coverage can start as early as the first day of the month you turn 65 if you enroll before that month ends.

Can I change my mind after I enroll in Medicare?

Yes, during the Annual Enrollment Period (October 15 through December 7 each year), you can switch between Original Medicare and Medicare Advantage, or change your Medigap plan. You can also add or change Part D coverage. Changes take effect January 1 of the following year.

What if I miss my enrollment window by a few months?

You can enroll during the General Enrollment Period (January 1 through March 31), but coverage will not start until July 1, and you will owe a permanent penalty on Part B and Part D premiums. If you had a may have access to life event like losing employer coverage, you may have a Special Enrollment Period lasting eight months.

Does Medicare start automatically when I turn 65?

No. You must actively enroll. If you are already receiving Social Security benefits, you may be enrolled automatically, but you should confirm this by checking your Social Security account or calling 1-800-MEDICARE to be certain.

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.