Medicare starts at age 65 for most people, but you can enroll earlier if you have a disability, end-stage renal disease, or ALS

You become may be able to access for Medicare the month you turn 65, regardless of whether you are still working. If you were born on the first of the month, your coverage begins the month before. For most people, enrollment happens automatically if you are already receiving Social Security benefits — Medicare Part A (hospital insurance) and Part B (medical insurance) start the first day of the month you turn 65.

If you have not yet claimed Social Security, you will need to enroll in Medicare yourself during your enrollment window. The initial enrollment period runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after. Missing this window can mean paying a permanent penalty on your Part B premiums, so the timing matters.

You can also start Medicare before 65 if you meet one of three conditions: you have been receiving Social Security Disability Insurance (SSDI) for at least 24 months, you have end-stage renal disease (ESRD) requiring dialysis or a transplant, or you have been diagnosed with amyotrophic lateral sclerosis (ALS). Each path has different timing rules.

Key Takeaways

  • You become may be able to access for Medicare at 65, and enrollment is automatic if you are already receiving Social Security.
  • If you have not claimed Social Security yet, you must enroll during your seven-month initial enrollment period or face a permanent penalty on Part B premiums.
  • You can start Medicare before 65 if you have been on SSDI for 24 months, have end-stage renal disease, or have been diagnosed with ALS.
  • Delaying Part B enrollment past your initial period can cost you more in premiums for the rest of your life, even if you enroll later.

Automatic enrollment at 65 if you receive Social Security

If you are already collecting Social Security retirement or disability benefits when you turn 65, Medicare Part A and Part B enroll you automatically. You do not need to do anything. The Social Security Administration shares your information with Medicare, and your coverage begins on the first day of the month you turn 65 (or the month before if you were born on the first).

You will receive a Medicare card in the mail about two weeks before your coverage starts. Check it for accuracy — your name, date of birth, and Medicare number should all be correct. If anything is wrong, contact Social Security or Medicare to fix it before your coverage begins.

Even though Part A and Part B enroll automatically, you still have choices to make. You can choose to decline Part B if you have other health coverage through an employer and do not want to pay the premium. You can also choose to enroll in a Medicare Advantage plan (Part C) or a prescription drug plan (Part D) instead of Original Medicare. These choices have their own important date, so review your options before your coverage starts.

Manual enrollment if you have not claimed Social Security yet

If you are not receiving Social Security when you turn 65, you must enroll in Medicare yourself. Your initial enrollment period is seven months long: it starts three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, your enrollment period runs from March through September.

You can enroll online through Medicare.gov, by phone at 1-800-MEDICARE, by mail, or in person at your local Social Security office. Online enrollment is usually the fastest — you can complete it in about 10 minutes if you have your Social Security number and birth certificate information ready.

If you miss your initial enrollment period and do not have a may have access to reason (called a "may have access to life event"), you will pay a permanent penalty on your Part B premiums. The penalty is 10 percent of the standard Part B premium for each full 12 months you were may be able to access but not enrolled. That penalty stays with you for life, even after you finally enroll. This is why staying within your enrollment window matters.

Starting Medicare before 65 with SSDI

If you have been receiving Social Security Disability Insurance (SSDI) for at least 24 months, you become may be able to access for Medicare at the start of your 25th month of benefits. You do not have to wait until 65. The 24-month waiting period is a federal rule that applies to everyone on SSDI, regardless of your age.

Like retirement beneficiaries, you are enrolled automatically once you reach 24 months of SSDI. You will receive your Medicare card in the mail, and coverage begins the first day of the month after your 24-month period ends. You do not need to take any action unless you want to decline Part B or choose a different plan type.

If you are on SSDI and approaching your 24-month mark, start thinking about your plan choices now. You will have the same options as someone turning 65 — Original Medicare (Part A and B), Medicare Advantage, or prescription drug coverage. Reviewing these before your card arrives means you can make informed choices rather than accepting defaults.

Starting Medicare before 65 with end-stage renal disease or ALS

If you have end-stage renal disease (ESRD) requiring dialysis or a kidney transplant, you become may be able to access for Medicare when ready upon diagnosis, regardless of age. You do not have to wait 24 months. The same applies if you have been diagnosed with amyotrophic lateral sclerosis (ALS) — you are may be able to access right away.

For ESRD, you must enroll yourself during your initial enrollment period, which is three months before the month your dialysis or transplant begins, the month it begins, and three months after. If your transplant happens unexpectedly, your enrollment period still runs from three months before through three months after the transplant date, even if you did not know it was coming.

For ALS, your initial enrollment period is the month you are diagnosed, plus the two months before and two months after — a total of five months. You can enroll online, by phone, or in person. If you miss your window, you may face a permanent penalty on Part B premiums, just as with age-based enrollment.

What happens if you miss your enrollment window

If you do not enroll during your initial enrollment period and do not have a may have access to reason for the delay, you will pay a penalty. For Part B, the penalty is 10 percent of the standard monthly premium for each full 12 months you were may be able to access but not enrolled. If the standard Part B premium is $165 per month and you were may be able to access for three years without enrolling, your penalty would be 30 percent — an extra $49.50 per month for life.

may have access to reasons (called "may have access to life events") include losing employer health coverage, moving out of your plan's service area, or certain changes in your family status. If you have a may have access to reason, you may be able to enroll outside your initial period without a penalty. You will need to document the reason and submit it to Medicare within 63 days of the event.

The best approach is to enroll during your initial window, even if you do not plan to use Medicare right away. You can delay using Part B if you have other coverage, but enrolling on time protects you from penalties.

Coordinating Medicare with employer health coverage

If you are still working and have health coverage through your employer when you turn 65, you may be able to delay Part B enrollment without a penalty. This is called creditable coverage. Your employer coverage must be based on your current employment (not retiree coverage), and your employer must have at least 20 employees.

If you have creditable coverage, you can decline Part B and keep your employer plan. When you eventually leave that job or lose the coverage, you have eight months to enroll in Part B without a penalty. You must enroll in Part A at 65, even if you decline Part B — Part A has no penalty for late enrollment if you have creditable coverage.

Before you decline Part B, confirm with your employer's benefits department that your coverage truly qualifies as creditable. If it does not and you decline Part B, you will owe a penalty when you eventually enroll. The penalty calculation is the same: 10 percent of the standard premium for each year you were may be able to access but not enrolled.

Frequently Asked Questions

What if I turn 65 on the first day of the month?

Your Medicare coverage begins the month before you turn 65. For example, if you were born on June 1, your coverage starts May 1. This rule applies whether you are automatically enrolled through Social Security or enrolling yourself.

Can I delay Medicare enrollment if I am still working?

You can delay Part B if you have creditable employer coverage based on current employment at a company with at least 20 employees. You must still enroll in Part A at 65. When you leave that job, you have eight months to enroll in Part B without a penalty.

What if I was on SSDI but my benefits were stopped?

Once you have been on SSDI for 24 months and become may be able to access for Medicare, you keep Medicare even if your SSDI benefits stop later. Your Medicare coverage does not end. You will continue to pay premiums, but your coverage remains active.

Do I have to enroll in Part D when I turn 65?

Part D (prescription drug coverage) is optional. If you do not enroll when you first become may be able to access and do not have other creditable drug coverage, you may pay a penalty when you do enroll. The penalty is about 1 percent of the national average Part D premium for each month you were may be able to access but not enrolled.

Can I change my mind after I enroll in Medicare?

Yes. You have a one-time opportunity to switch from Original Medicare to Medicare Advantage (or vice versa) during the Annual Enrollment Period, which runs October 15 through December 7 each year. Changes take effect January 1. You can also switch prescription drug plans during this same window.