The Three Main Ages and Situations When Medicare Starts

You can start Medicare at age 65, or earlier if you have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if you have end-stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS). Most people become may be able to access at 65 regardless of work history. If you are already getting SSDI, Medicare begins automatically two years after your disability payments started. If you have ESRD or ALS, you can start Medicare as soon as your condition is diagnosed and documented, with no age requirement.

The timing matters because Medicare has enrollment periods tied to your birthday month and your first may be able to access date. Missing these windows can cost you in late penalties that last for life. The rules differ slightly depending on which path you take to Medicare, so knowing which one applies to you determines when you can actually sign up.

Key Takeaways

  • You become may be able to access for Medicare at age 65, or earlier if you have been on SSDI for 24 months, or when ready if you have ESRD or ALS.
  • Your Initial Enrollment Period is the seven-month window centered on your birthday month in the year you turn 65 (or become may be able to access through disability or ESRD/ALS).
  • If you miss your Initial Enrollment Period and do not have employer coverage, you will pay a permanent penalty on Part B and Part D premiums.
  • You can change your Medicare plan once per year during the Annual Enrollment Period, which runs October 15 through December 7.
  • Social Security will tell you when you are may be able to access and can walk you through the enrollment process by phone or in person.

Medicare at Age 65: The Standard Path

The most common way to start Medicare is turning 65. You become may be able to access on the first day of the month in which you turn 65, or on the first day of the month after your birthday if you turn 65 on the first of the month. You do not have to be retired, and you do not have to stop working. You do not have to have paid into Medicare through payroll taxes, though most people have.

Your Initial Enrollment Period runs for seven months: three months before your birthday month, your birthday month itself, and three months after. If your birthday is in June, your enrollment period is March through September. You can sign up anytime during this window. If you sign up in your birthday month or later, your coverage starts the first day of the following month. If you sign up before your birthday month, coverage typically starts the first day of your birthday month.

You should sign up even if you plan to keep working and stay on your employer's health plan. If you miss this window and your employer plan is not considered "creditable coverage" (a term your employer's benefits office can confirm), you will owe a permanent 10 percent penalty on your Part B premium for each full year you were may be able to access but not enrolled. This penalty stays with you for life, even after you leave your job.

Starting Medicare Through SSDI: The 24-Month Rule

If you are receiving Social Security Disability Insurance, you become may be able to access for Medicare automatically 24 months after your disability payments began. You do not have to do anything to become may be able to access — Social Security tracks this date for you. Your may be able to access date is the first day of the 25th month of your SSDI payments.

Your Initial Enrollment Period still runs for seven months, centered on the month you become may be able to access. If you became may be able to access in March, you can sign up from December through June. Social Security will send you a notice about three months before your may be able to access date, and you can sign up through that notice, online at Medicare.gov, or by calling 1-800-MEDICARE. Many people on SSDI are automatically enrolled in Medicare Part A (hospital insurance) and do not need to take action, but you must actively sign up for Part B (medical insurance) and Part D (prescription drug coverage) if you want them.

The same late-enrollment penalty applies if you miss this window. If you have employer coverage through a job or a family member's job, you may be able to delay Part B without penalty, but you must document this coverage and request a Special Enrollment Period from Social Security.

Starting Medicare With ESRD or ALS: when ready may be able to access

If you have end-stage renal disease (ESRD) — permanent kidney failure requiring dialysis or transplant — or amyotrophic lateral sclerosis (ALS), you can start Medicare when ready upon diagnosis, regardless of age. There is no age requirement and no waiting period. Your may be able to access date is the first day of the month in which your condition is diagnosed, or the first day of the following month if you are diagnosed on the first of the month.

Your Initial Enrollment Period is still seven months, centered on your may be able to access month. You must sign up during this window to avoid late penalties. If you have ESRD, you may already be in contact with a dialysis center or transplant team — ask them to help you understand your Medicare options, as they often have staff who work with new Medicare patients. If you have ALS, your neurologist or ALS Association chapter can point you toward enrollment resources.

What Happens If You Miss Your Initial Enrollment Period

If you do not sign up during your seven-month Initial Enrollment Period and you do not have creditable coverage (employer coverage that is at least as good as Medicare), you will face permanent penalties. Part B late enrollment penalty is 10 percent of the standard premium for each full year you were may be able to access but not enrolled. If you were may be able to access for three years and did not sign up, your penalty is 30 percent of the Part B premium, and you will pay this penalty for as long as you have Medicare.

Part D (prescription drug) late enrollment penalty works the same way: 1 percent of the national average Part D premium for each month you were may be able to access but not enrolled. These penalties do not go away if you eventually sign up. You can still sign up after missing your Initial Enrollment Period, but only during the General Enrollment Period (January 1 through March 31 each year), and your coverage will not start until July 1 of that year.

The one exception is if you had creditable coverage — employer health insurance, TRICARE, Veterans coverage, or certain other plans — during the time you were may be able to access. If you can document this, you can request a Special Enrollment Period and sign up without penalty. You will need to provide proof of your coverage dates.

Changing Your Plan After You Start Medicare

Once you are enrolled in Medicare, you can change your plan during the Annual Enrollment Period, which runs October 15 through December 7 each year. During this window, you can switch from Original Medicare to a Medicare Advantage plan, from Medicare Advantage back to Original Medicare, change which Medicare Advantage plan you are in, or change your Part D prescription drug plan. Changes made during this period take effect January 1 of the following year.

If you have a may have access to life event — you move out of your plan's service area, lose employer coverage, get married or divorced, or have a significant change in income — you may be able to make changes outside the Annual Enrollment Period through a Special Enrollment Period. These windows are usually 60 days long and must be requested within 60 days of the event. Social Security or Medicare can tell you whether your situation qualifies.

How to Sign Up for Medicare

You can sign up for Medicare 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. If you are already receiving Social Security retirement or disability benefits, you may be automatically enrolled in Part A (hospital insurance) when you become may be able to access, but you still need to sign up for Part B and Part D yourself unless you opt out.

Have your Social Security number ready, and know the month and year you became may be able to access. If you are signing up for Part D, have a list of your current medications so you can compare plans. If you are considering Medicare Advantage, know which doctors and hospitals you want to use, because coverage varies by plan. You do not need to choose a plan on the spot — you can take time to compare options during your enrollment period.

Frequently Asked Questions

Can I start Medicare before I turn 65?

Yes, if you have been on SSDI for 24 months, or if you have ESRD or ALS. Otherwise, you must wait until 65. If you are close to 65 and have a serious health condition, talk to your doctor about whether you might may have access to for disability, as this can open an earlier Medicare path.

What if I am still working at 65?

You can stay on your employer plan and delay Medicare Part B without penalty if your employer has 20 or more employees. You must sign up for Part A (hospital insurance) during your Initial Enrollment Period to avoid penalties. Ask your employer's benefits office whether your plan is considered creditable coverage for Medicare purposes.

Do I have to choose a plan during my enrollment period?

No. You can sign up for Medicare without choosing a specific plan during your Initial Enrollment Period. If you do not choose, you will be enrolled in Original Medicare (Part A and Part B). You can then choose a Part D plan or Medicare Advantage plan during the Annual Enrollment Period in October.

What if I turned 65 and did not sign up?

You can still sign up during the General Enrollment Period (January 1 through March 31), but your coverage will not start until July 1, and you will owe a permanent late penalty on Part B and Part D unless you had creditable coverage. Contact Social Security or 1-800-MEDICARE to request a Special Enrollment Period if you had employer coverage during the time you were may be able to access.

How do I know if my employer coverage is creditable?

Ask your employer's benefits office directly. They should be able to tell you whether your plan meets Medicare's definition of creditable coverage. If it does, you can delay Part B without penalty. Get this in writing so you have proof if you need to request a Special Enrollment Period later.