When Medicare Starts: Age, Disability, and Timing Rules

Medicare begins at 65 for most people, but you can start earlier if you have a disability or end-stage renal disease

Medicare enrollment opens three months before the month you turn 65. You do not have to wait until your birthday to sign up — the earliest you can enroll is three months prior. If you miss that window, you can still enroll during the general enrollment period from January 1 to March 31 each year, but you may face a permanent penalty on your premiums.

You are not required to take Medicare at 65 if you are still working and covered by an employer health plan. However, if you do not enroll when you first become may be able to access and you do not have employer coverage, you will pay a 10 percent penalty on Part B premiums for each year you delayed. The penalty stays with you for life.

If you are already receiving Social Security benefits, Medicare will start automatically the month you turn 65. If you are not yet taking Social Security, you must enroll in Medicare separately through Medicare.gov, by phone at 1-800-MEDICARE, or at your local Social Security office.

Key Takeaways

You can enroll in Medicare three months before you turn 65, and enrollment opens automatically if you are already collecting Social Security.
If you miss your initial enrollment window and do not have employer coverage, you will pay a permanent 10 percent penalty on Part B premiums.
You can delay Medicare without penalty only if you are covered by an active employer health plan or your spouse's employer plan.
People under 65 with a disability or end-stage renal disease can enroll in Medicare after 24 months of receiving Social Security Disability Insurance or after a diagnosis of kidney failure.

Starting Medicare before 65 due to disability

If you receive Social Security Disability Insurance (SSDI), you become may be able to access for Medicare after you have been on disability for 24 months. The 24-month clock starts from the month your disability benefits begin, not from the month you applied. You do not need to do anything — Medicare will start automatically in the 25th month of your SSDI benefits.

You will receive a Medicare card in the mail before your coverage begins. Part A (hospital insurance) and Part B (medical insurance) both start on the same day. If you want to decline Part B, you must contact Medicare before your coverage date, though most people keep both parts because Part B covers doctor visits and outpatient care.

If you are on Supplemental Security Income (SSI) instead of SSDI, the rules are different. SSI recipients become may be able to access for Medicare after they have been on SSI for 24 months, but the timing depends on when your SSI payments began. Contact Social Security to confirm your exact start date.

Starting Medicare with end-stage renal disease

If you have end-stage renal disease (ESRD) — permanent kidney failure requiring dialysis or a transplant — you become may be able to access for Medicare regardless of age. Your may be able to access begins in the month you start dialysis treatment or the month of your kidney transplant, whichever comes first. If you receive a pre-emptive transplant before dialysis, your Medicare coverage begins the month of the transplant.

You must enroll in Medicare yourself; it does not start automatically. Contact Medicare.gov, call 1-800-MEDICARE, or visit your local Social Security office to enroll. You have a special enrollment period, meaning you can enroll at any time without facing a penalty for late enrollment.

Medicare covers dialysis, transplant surgery, and related care. However, you may still want to enroll in a Medigap or Medicare Advantage plan to cover costs Medicare does not pay. Many people with ESRD also may have access to for Medicaid, which can help with copayments and premiums.

Coordinating Medicare with employer health insurance

If you are still working at 65 and your employer has 20 or more employees, you can delay Medicare Part B without penalty. Your employer plan is considered the primary payer, and Medicare becomes secondary. You must enroll in Part A (hospital insurance) even if you delay Part B, because Part A has no penalty for late enrollment.

Once you leave your job or your employer coverage ends, you have eight months to enroll in Part B without facing a penalty. This is called a Special Enrollment Period. If you miss this window, you will owe the 10 percent penalty for each year you were may be able to access but not enrolled.

If your spouse is still working and you are covered under their employer plan, the same rules explore — you can delay Part B without penalty, but you must enroll in Part A. When your spouse retires or their coverage ends, you have eight months to enroll in Part B penalty-free.

What happens if you miss your enrollment window

If you do not enroll in Medicare Part B during your initial enrollment period and you do not have employer coverage, you will pay a permanent 10 percent penalty on your Part B premiums. The penalty applies for as long as you have Medicare, even if you enroll years later.

You can still enroll during the general enrollment period from January 1 to March 31 each year. Your coverage will begin on July 1 of that year. However, you will owe the penalty retroactively from the month you first became may be able to access.

The only way to avoid the penalty is to prove you had creditable coverage — employer insurance, TRICARE, or another plan that covered medical services — during the time you were not enrolled in Medicare. You will need documentation from your former insurance company to show this.

Delaying Social Security while taking Medicare

You can take Medicare at 65 and delay Social Security benefits until 70 to receive a larger monthly payment. These are separate decisions. Medicare enrollment and Social Security enrollment are not linked, so you can choose one without choosing the other.

If you delay Social Security past 65, your monthly benefit increases by about 8 percent per year until age 70. However, you still need to enroll in Medicare at 65 to avoid the Part B penalty. You can enroll in Medicare and not take Social Security benefits at the same time.

If you are still working and delaying both Medicare and Social Security, make sure you understand the earnings test. Social Security reduces your benefit if you earn above a certain amount before your full retirement age. Medicare has no earnings test — you can work and take Medicare at the same time without any reduction in coverage.

Medicare enrollment for people on disability past age 65

If you have been on SSDI since before age 65, your Medicare coverage continues automatically after you turn 65. You do not need to enroll again. Your Medicare card will remain the same, and your coverage does not change.

However, if you are on SSDI and turn 65, you should check your Medicare coverage to make sure both Part A and Part B are active. Some people on disability have Part A only, and they may want to add Part B. You can enroll in Part B at any time after age 65, but you will owe a penalty if you did not enroll when you first became may be able to access at 65.

If you are no longer on SSDI by the time you turn 65 — for example, because your condition improved or you returned to work — you will need to enroll in Medicare yourself during your initial enrollment period. Contact Medicare or Social Security to confirm your status.

Frequently Asked Questions

Can I enroll in Medicare before I turn 65?

Yes, if you have a disability and have been on SSDI for 24 months, or if you have end-stage renal disease. Otherwise, you must wait until three months before you turn 65. You cannot enroll early just because you want to.

What if I am still working at 65 and do not want Medicare yet?

You can delay Part B if your employer has 20 or more employees and you are covered by their health plan. You must still enroll in Part A. When you leave your job, you have eight months to enroll in Part B without a penalty.

Do I lose my employer insurance when I turn 65?

No. Your employer coverage continues as long as you work there and pay your share of the premium. However, once you enroll in Medicare, Medicare becomes primary and your employer plan becomes secondary. You should tell your employer's benefits office that you have Medicare so they can coordinate payments correctly.

What is the penalty for enrolling late in Medicare Part B?

You pay a permanent 10 percent increase on your Part B premium for each year you were may be able to access but not enrolled. This penalty stays with you for life, even if you move to a different plan. The only exception is if you had creditable employer coverage during the time you were not enrolled.

If I am on SSDI, do I have to do anything to get Medicare?

No. Medicare starts automatically in the 25th month of your SSDI benefits. You will receive a Medicare card in the mail. You do not need to explore or contact anyone, though you can call Medicare if you have questions about your coverage.

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.