The Standard Age and How to Start

You can start Medicare on the first day of the month you turn 65, or the month after, depending on when your birthday falls. Most people become covered automatically if they are already receiving Social Security benefits — you do not have to do anything. If you are not yet taking Social Security, you will need to contact Social Security directly to enroll in Medicare, even if you do not want Social Security payments yet.

The enrollment window opens three months before the month you turn 65 and closes three months after. If you miss this window and do not have coverage through an employer or union, you may face a permanent penalty on your premiums. The penalty is 10 percent per year for every 12 months you delay, and it stays with you for life.

You can enroll by phone with Social Security at 1-800-772-1213, online at ssa.gov, or in person at your local Social Security office. Have your birth certificate, proof of citizenship or legal residency, and bank account information ready if you plan to set up direct deposit for any benefits.

Key Takeaways

  • Medicare begins on the first day of the month you turn 65, or the first day of the following month if your birthday is late in the month.
  • If you receive Social Security, Medicare enrollment happens automatically; if you do not, you must contact Social Security to enroll even if you delay taking benefits.
  • You have a seven-month window to enroll — three months before you turn 65 and three months after — and missing it can result in a permanent 10 percent annual penalty.
  • Enrollment is free and happens through Social Security by phone, online, or in person; you do not pay to sign up.

Enrolling Before Age 65 if You Have Certain Disabilities

If you have been receiving Social Security Disability Insurance (SSDI) for 24 months, you become covered by Medicare automatically, regardless of your age. This means someone who became disabled at 40 and received SSDI for two years would be on Medicare at 42. The coverage begins in the 25th month of your SSDI may be able to access, not the month you explore.

If you have end-stage renal disease (permanent kidney failure requiring dialysis or a transplant) or amyotrophic lateral sclerosis (ALS), you may be covered by Medicare as soon as the month your condition is diagnosed, without waiting for any period of disability benefits. You will still need to contact Social Security to confirm your enrollment, as coverage does not always happen automatically in these cases.

Continuing Coverage if You Work Past 65

You can delay Medicare and stay on your employer's health plan if you are still working and your employer has 20 or more employees. However, you must still enroll in Medicare Part A (hospital insurance) when you turn 65, even if you do not use it. Delaying Part A enrollment can result in a permanent penalty if you later need it.

Part B (medical insurance) can be delayed without penalty if you have employer coverage and meet certain conditions — your employer must certify that you are covered under their plan as an active employee. When you leave your job or lose that coverage, you have eight months to enroll in Part B without penalty. After that window closes, the 10 percent annual penalty applies for each year you delayed.

What Happens at Your Medicare Start Date

On your Medicare start date, Part A (hospital insurance) and Part B (medical insurance) coverage begin. You will receive a Medicare card in the mail, usually two to three weeks before your coverage starts. The card shows your Medicare number, which you will use to identify yourself at doctors' offices and hospitals.

Part A has no monthly premium for most people (you paid for it through payroll taxes while working). Part B has a monthly premium that is deducted from your Social Security check or billed separately if you do not receive Social Security. The standard Part B premium changes each year; contact Social Security or visit Medicare.gov to learn the current amount.

You will also need to decide whether to enroll in Part D (prescription drug coverage) or a Medicare Advantage plan (Part C) during your initial enrollment period. These choices affect your out-of-pocket costs and which doctors and pharmacies you can use. If you do not choose Part D during your initial enrollment window, you may face a permanent penalty when you do enroll later.

Special Situations: Delayed Enrollment and Exceptions

If you miss your initial enrollment window, you can still enroll during the General Enrollment Period, which runs from January 1 to March 31 each year. Coverage would begin July 1 of that year. However, you will owe the permanent penalty on Part B and Part D unless you have proof of creditable coverage (such as an employer plan that is at least as good as Medicare).

If you are a federal employee, railroad retiree, or covered under TRICARE (military health coverage), your enrollment rules may differ. Contact your benefits administrator before your 65th birthday to understand your specific timeline and options.

If you are not yet a U.S. citizen but have a valid visa and work history, you may still be covered by Medicare at 65. Permanent residents and some other visa holders can enroll. Bring your visa and work history documentation when you contact Social Security.

How to Prepare Before Your 65th Birthday

Start the process three months before you turn 65. Gather your birth certificate, proof of citizenship (passport, naturalization papers, or state ID), and your Social Security number. If you are not yet receiving Social Security, decide whether you want to claim benefits now or delay — this decision is separate from Medicare enrollment, though both happen through Social Security.

Review your current health coverage and prescription drugs. Write down which medications you take and which doctors and specialists you see regularly. This information will help you choose a Part D plan and decide whether Original Medicare or a Medicare Advantage plan makes more sense for you.

If you are still working, ask your employer's benefits department whether your health plan will continue after you turn 65 and whether you need to do anything to keep it. Some employers require you to enroll in Medicare Part A and B even if you stay on their plan.

Frequently Asked Questions

What if my birthday is on the first day of the month?

Your Medicare coverage begins on that date. Your enrollment window opens three months before (the first of the month three months prior) and closes three months after (the last day of the month three months later).

Can I enroll in Medicare before I turn 65?

You can contact Social Security up to four months before your 65th birthday to ask questions and prepare, but your official enrollment window does not open until three months before the month you turn 65. If you have SSDI or end-stage renal disease, different rules explore — contact Social Security about your specific situation.

Do I have to take Social Security to get Medicare?

No. You can enroll in Medicare at 65 without claiming Social Security benefits. However, you must contact Social Security directly to enroll in Medicare if you are not already receiving Social Security payments. Delaying Social Security does not delay Medicare.

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

You must still enroll in Medicare Part A at 65. You may be able to delay Part B if your employer has 20 or more employees and you are covered as an active employee. When you leave your job, you have eight months to enroll in Part B without penalty.

What happens if I miss the enrollment important date?

You can enroll during the General Enrollment Period (January 1 to March 31), with coverage starting July 1. However, you will owe a permanent 10 percent penalty on Part B and Part D for each year you delayed, unless you have proof of creditable coverage from an employer or other source.