Medicare begins at age 65 for most people

You become may be able to access for Medicare on the first day of the month you turn 65, or the month after, depending on your birthday. If you turn 65 on the first of any month, coverage starts that same month. If your birthday is any other day, coverage starts the first day of the following month.

You do not have to wait until you actually turn 65 to sign up. You can enroll starting three months before the month you turn 65. This three-month window is called your Initial Enrollment Period, and it lasts for seven months total — three months before, the month you turn 65, and three months after.

If you miss this window, you can still sign up later, but you may pay higher premiums for the rest of your life. The penalty depends on how long you waited and which part of Medicare you are signing up for.

Key Takeaways

  • Medicare coverage starts the first day of the month you turn 65, or the first day of the month after your birthday.
  • You can sign up three months before you turn 65, during the month you turn 65, or up to three months after — a seven-month window called your Initial Enrollment Period.
  • Some people under 65 with disabilities or end-stage renal disease may be may be able to access for Medicare, but the rules are different.
  • If you delay signing up past your Initial Enrollment Period, you will likely pay higher premiums permanently.
  • You must sign up even if you plan to keep working, unless your employer has 20 or more employees and covers you through their health plan.

Who can start Medicare before age 65

Most people wait until 65, but some younger people may have access to. If you have been receiving Social Security Disability Insurance (SSDI) for 24 months, you become may be able to access for Medicare at any age. The 24 months starts from the date your disability benefits began, not from when you applied.

You also may have access to if you have end-stage renal disease (ESRD) — permanent kidney failure requiring dialysis or a transplant. With ESRD, you can sign up for Medicare as soon as your doctor determines you need dialysis or a transplant, regardless of age. If you are already on dialysis, you may be able to start coverage the month your treatment begins.

A third group is people with amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease. You become may be able to access for Medicare the same month your SSDI benefits start, with no 24-month waiting period.

What happens if you miss your enrollment window

If you do not sign up during your seven-month Initial Enrollment Period, you can still sign up later during the General Enrollment Period, which runs from January 1 to March 31 each year. Coverage would start July 1 of that year. But waiting costs money.

For Part B (doctor visits and outpatient care), you pay a 10 percent higher premium for each year you delayed, for as long as you have Medicare. If you waited five years, your premium stays 50 percent higher permanently. The same penalty applies to Part D (prescription drug coverage) if you go without creditable drug coverage.

For Part A (hospital care), there is usually no penalty if you have been covered by an employer plan. But if you did not have coverage and delayed, you may owe a penalty.

Signing up while you are still working

You must sign up for Medicare at 65 even if you are still working and have health insurance through your job. The only exception is if your employer has 20 or more employees. In that case, you can delay Part B without penalty as long as you are covered by the employer plan and actively working.

If your employer has fewer than 20 employees, you must sign up for Part B when you turn 65 or face a penalty, even though you will have two insurance plans. Your employer plan will be primary (pays first), and Medicare will be secondary.

Once you leave your job or lose the employer coverage, you have eight months to sign up for Part B without penalty. This is called a Special Enrollment Period.

How to sign up for Medicare

You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. You will need your Social Security number and proof of citizenship or legal residency.

If you are already receiving Social Security benefits, you may be signed up automatically. Social Security will send you a notice in the mail about three months before you turn 65. Check that notice carefully — it tells you what parts you are enrolled in and when coverage starts.

If you are not yet receiving Social Security, you must sign up for Medicare separately. Do not assume that signing up for Social Security at 65 will automatically enroll you in Medicare — you need to take that step yourself.

Medicare coverage types and what they cover

Part A covers hospital stays, skilled nursing facility care, hospice, and some home health care. Most people do not pay a monthly premium for Part A if they or their spouse paid Medicare taxes while working for at least 10 years.

Part B covers doctor visits, outpatient surgery, tests, and equipment like wheelchairs. You pay a monthly premium, which varies based on your income. In 2024, the standard premium was $164.90 per month, but higher earners pay more.

Part D is prescription drug coverage. You choose a plan from private insurance companies, and costs vary widely. You must have Part D or other creditable drug coverage by the time you turn 65, or you will pay a penalty if you sign up later.

Part C, also called Medicare Advantage, is an alternative to Parts A, B, and D. It is offered by private insurance companies and often includes drug coverage and dental or vision benefits. You can choose Part C instead of Original Medicare, but you must have Part A and Part B first.

Questions to ask your doctor or Social Security office

Before you turn 65, ask your doctor whether you should sign up for Part D even if you do not take many medications. Ask about the penalty for late enrollment and whether any of your current medications are covered by the plans available in your area.

If you are still working, ask your employer's benefits department whether your health plan is considered creditable coverage for drug benefits. This affects whether you can delay Part D without penalty.

Ask Social Security or Medicare whether you will be signed up automatically or whether you need to take action yourself. Get the answer in writing if possible, so you have proof of what you were told.

Frequently Asked Questions

Can I sign up for Medicare before I turn 65?

You can sign up starting three months before the month you turn 65. This is your Initial Enrollment Period. If you are under 65 and have SSDI, end-stage renal disease, or ALS, you may be may be able to access to sign up at any time.

What if I am still working at 65 and have health insurance through my job?

You must sign up for Medicare Part B at 65 unless your employer has 20 or more employees and you are actively working. If your employer is large enough, you can delay Part B without penalty. Once you leave the job, you have eight months to sign up without penalty.

Do I have to choose between my employer plan and Medicare?

No. You can have both. Your employer plan will usually pay first, and Medicare will pay second. But you must be enrolled in both — signing up for one does not automatically enroll you in the other.

What happens if I turn 65 and do not sign up for Medicare?

You can sign up later during the General Enrollment Period (January 1 to March 31), but coverage does not start until July 1. You will also pay higher premiums for Part B and Part D for the rest of your life if you had no creditable coverage during the gap.

Will Social Security automatically sign me up for Medicare?

If you are already receiving Social Security at 65, you will usually be signed up automatically for Parts A and B. Social Security will mail you a notice. If you are not yet receiving Social Security, you must sign up for Medicare separately — it does not happen automatically.