When Does Medicare Start?

Medicare starts at age 65, or earlier for those living with certain disabilities. The actual date of coverage depends on when you sign up.
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Written by Liz Weston, CFP®
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Nerdy takeaways
  • Most people can sign up for Medicare at age 65.

  • If you're living with a disability or with certain conditions, Medicare can start sooner.

  • If you get health insurance from an employer with 20 or more workers, you may be able to delay Medicare.

  • There are penalties for missing enrollment dates.

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When does Medicare start?

Medicare coverage typically starts when people turn 65. But if they're receiving health insurance from an employer (or a spouse's employer) with 20 or more employees, they can delay their start to Medicare. People are automatically enrolled if they’re receiving Social Security benefits. Otherwise, they must enroll themselves.

Original Medicare includes Medicare Part A, which covers hospitals, and Medicare Part B, which covers doctor visits and outpatient services. Most people get premium-free Medicare Part A, while Medicare Part B requires paying monthly premiums.

Once enrolled, you can choose to buy additional private insurance, which includes Part D prescription drug plans, Medicare Supplement or Medigap policies, and Medicare Advantage plans — also known as Medicare Part C. Medicare Advantage plans, which bundle the parts of Medicare, include all the benefits of Parts A and B and usually Part D as well, but you must still enroll in Medicare Parts A and B and pay your monthly Part B premium.

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Medicare age and eligibility

People are eligible for Medicare when they're age 65 or older, or when they're younger than 65 if they're living with certain disabilities. Medicare is also available for people with end-stage renal disease or with Lou Gehrig’s disease, also known as ALS. Medicare start dates vary depending on how you’re eligible.

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When Medicare starts: Turning 65

Medicare coverage can start as early as the first day of the month in which you turn 65, unless you were born on the first of the month. In that case, your coverage can begin on the first day of the previous month.

Generally, you're automatically enrolled in Medicare at age 65 if you've already claimed Social Security benefits.

If you have to enroll yourself, you should sign up in the three months before your birthday to avoid any coverage gap. Your initial enrollment period includes your 65th birthday month, plus the three months before and after. But if you enroll during your birthday month or the two to three months after, coverage won’t start until the following month. (Enroll in the three months before, and coverage starts on the first day of your birthday month.)

🤓Nerdy Tip

If your birthday is the first of the month, your enrollment period includes the four months before your birthday month, your birthday month and the two months after.

When Medicare starts: People living with certain disabilities

Medicare also covers certain people under age 65 who have disabilities severe enough that they qualify for Social Security Disability Insurance, or SSDI. Here’s when their Medicare coverage starts:

  • People who get disability benefits from Social Security automatically receive Medicare coverage after 24 months.

  • People who have ALS automatically receive Medicare coverage the same month that disability benefits start.

  • People who have end-stage renal disease usually can apply for Medicare starting on the first day of the fourth month of dialysis treatments. However, there are several additional conditions and opportunities to start Medicare at different points. And if they’re getting a kidney transplant, Medicare coverage can start the month they’re admitted to a hospital for the transplant, if the transplant happens that month or within the next two months. Transplant delays may move Medicare’s starting date out, too.

When Medicare starts: General enrollment period

If you miss your initial enrollment period, you can sign up for premium-free Part A anytime, but you must wait until Medicare’s general enrollment period, Jan. 1 to March 31, to sign up for the other parts — unless you have a special enrollment period. Coverage starts the month after you sign up. Those who miss the initial enrollment period for Part B and Part D usually have to pay permanently higher premiums due to penalties.

When Medicare starts: Special enrollment periods

You can qualify for a special enrollment period and avoid penalties in a few circumstances, such as when you’re covered by a group health insurance plan from a current employer with 20 or more employees — either your own employer or your spouse’s. In that case, the clock starts ticking when the employment or the coverage ends, whichever comes first. (Note: COBRA and retiree health coverage do not extend this clock.)

At that point, you have two months to enroll in Medicare Advantage or Part D, and eight months to enroll in Medicare Part B. (Though if you enroll in a Medicare Advantage plan, you’ll have to enroll in Part B at that time.) If you apply using a special enrollment period and your application is approved, your coverage starts the first day of the following month.

Other things that might qualify you for an SEP include missing a chance to sign up because you were affected by a natural disaster or missing a chance to enroll because a health plan or employer gave you incorrect information. To apply for an SEP, fill out the Application for Medicare Part A and Part B Special Enrollment Period and fax or mail to your local Social Security office.

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Medicare start date

The date your coverage starts will depend on when you sign up for Medicare:

When you sign up for Medicare

When your Medicare coverage starts

Before the month of your 65th birthday.*

The month you turn 65.

The month you turn 65 or during the three months after.

The next month.

During the general enrollment period, which runs Jan. 1 to March 31 each year.

The month after you sign up.

During a special enrollment period.

The next month.

*If your birthday is on the first of the month, your coverage will start on the first day of the month before your birthday month. For example, if you turn 65 on Aug. 1, your coverage will start July 1.

Coverage always starts on the first day of the month. If you’re unsure when you can sign up for Medicare, check your specific situation with Medicare directly.

Frequently asked questions

If you’ve applied for Social Security or benefits from the Railroad Retirement Board, you’ll automatically get Medicare Part A when you become eligible for Medicare. If you’ve been getting benefits for at least four months before age 65, you’ll get Part A and Part B when you turn 65. You can choose whether to keep Part B, depending on your situation. If you haven't applied for Social Security and you have to enroll yourself in Medicare, you can sign up during your initial enrollment period, which includes your 65th birthday month plus the three months before and after.

Medicare starts for most people at age 65, unless you’re living with a disability or specific conditions such as end-stage renal disease or amyotrophic lateral sclerosis, otherwise known as Lou Gehrig’s disease or ALS. In those cases, it may start earlier than age 65.

People receiving Social Security disability benefits are typically automatically enrolled in Medicare after 24 months of disability benefit eligibility. People with ALS get Medicare coverage the same month they get their first disability check.

People with end-stage renal disease who need dialysis or a kidney transplant are eligible for Medicare. Get more information on ESRD and Medicare here.

For everyone else, your initial enrollment period for Medicare includes the month you turn 65 and the three months before and after it.

No matter when you sign up, your Medicare coverage will start on the first of the month. If you sign up before your 65th birthday month, coverage will start on the first day of the month you turn 65. If you sign up during your birthday month or the two to three months after, coverage will start on the first day of the following month. If your birthday is on the first of the month, your coverage can start as early as the first day of the previous month.

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