Medicare Part A Eligibility and Enrollment

Written by:

Bryan Strickland

Reviewed by:

Jason Kolkey

Key Takeaways

Eligibility for Medicare Part A, which is hospital insurance, typically begins at age 65 for U.S. citizens.
You don’t have to pay a monthly premium if you have paid Medicare taxes through an employer for 10 years or more.
You are automatically enrolled leading up to your 65th birthday if you begin receiving Social Security benefits at least four months before you turn 65.
If you don’t have a premium, you can enroll in Part A at any time, but generally there’s no reason why you would delay beyond age 65.
If you do owe a premium, your chances to enroll after 65 could be limited and you could face a late enrollment penalty.

Medicare Part A Eligibility

Most U.S. citizens and permanent residents are eligible for Medicare Part A, the part of Original Medicare that provides hospital insurance, when they turn 65. You can become eligible sooner under one of these circumstances:

You’ve been diagnosed with amyotrophic lateral sclerosis (ALS ).
You have end-stage renal disease (ESRD).
You have received Social Security disability benefits for at least two years.

Is There a Premium for Medicare Part A?

Who is eligible for premium-free Medicare Part A ?

Almost everyone!

(However, you’re still responsible for a deductible and potentially other costs when you use your coverage).

According to the Centers for Medicare & Medicaid Services, about 99% of people on Medicare qualify for Part A coverage without a monthly premium. That’s because the Medicare program is fueled by Medicare taxes taken out of paychecks. If you have paid those taxes for at least 40 quarters (10 years) over your lifetime, then you qualify for Part A without a monthly premium.

If you haven’t worked that long, you likely owe a monthly premium (and you must also enroll in Part B if you want Part A).

Is My Spouse Eligible for Medicare Part A?

Medicare eligibility and enrollment is an individual thing, so the rules regarding Medicare Part A spouse eligibility are the same for both people. However, it is possible for a spouse to help you qualify for Part A without a monthly premium.

Here’s how it works: If you don’t qualify for a no-cost Part A premium, you can use your spouse’s work history to qualify. That means if you haven’t paid Medicare taxes for 10 years but your spouse (or former spouse) has, you are eligible for Part A without a premium.

One caveat: Your spouse must be at least 62 years old. And remember, Medicare Part A eligibility is on an individual basis, so your spouse still won’t qualify for Part A themselves until age 65 (unless they’re eligible because of a disability).

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Medicare Part A Enrollment

If you’re already receiving Social Security benefits (or Railroad Retirement Board benefits) for at least four months leading up to your 65th birthday, you will be automatically enrolled in Medicare Part A (as well as Medicare Part B). Automatic enrollment is becoming less common for as legislation has pushed the age for receiving full Social Security benefits beyond 65.

So, you may have to take a little initiative to enroll in Medicare Part A by either:

Applying online with the Social Security Administration.
Calling 1-800-772-1213 to apply (TTY: 1-800-325-0778).
Visiting a local Social Security office.

For most people, the first chance to enroll in Medicare Part A and Part B (which is medical insurance) is a seven-month period surrounding your 65th birthday. This is called your Initial Enrollment Period.

Your Initial Enrollment Period includes the three months before you turn 65, the month you turn 65 and the three months afterward (or, if your birthday falls on the first day of the month, it’s the four months before your birthday, the month you turn 65 and the two months afterward).

If you enroll in Part A in the months leading up to your birthday, coverage will begin the first day of your birthday month (or, if your birthday is on the first of the month, coverage begins the first day of the month before your birthday).

If you enroll in Part A within six months of your 65th birthday, your coverage is retroactive to the first day of your birthday month (or, if your birthday is on the first of the month, coverage begins the first day of the month before your birthday).

How Do I Sign Up for Medicare Part A Only?

If you have health insurance from another source, such as a policy provided by an employer, you might choose to delay enrolling in Medicare Part B, which charges a monthly premium. Part A can help with your hospital bills even if you already have coverage through employer insurance, acting as secondary payer in most cases.

You can contact the Social Security Administration to join just Part A or to opt out of Part B when you’re automatically enrolled.

However, you must have both Parts A and B of Original Medicare to add a Medigap Supplement (Medigap) plan or switch to a Medicare Advantage plan from a private insurance carrier.

When you lose your existing coverage, you will qualify for a Special Enrollment Period to join Medicare Part B. Delaying enrollment if you don’t have other coverage could result in a paying a penalty when you do join.

Is There Any Reason To Pass on Medicare Part A at Age 65?

One reason for passing on Part A at age 65 would be if you haven’t worked at least 10 years and are required to pay a monthly premium. While those premiums can add up, the coverage might still might be worth it depending on your specific situation.

Late Enrollment When You Don’t Have To Pay a Part A Monthly Premium

If you’re not responsible for a monthly Part A premium, then you can sign up at any time.

When you sign up during your Initial Enrollment Period or within six months after you turn 65, you will be covered by Part A beginning on the first day of the month you turn 65.
If you sign up later than that, your coverage will be retroactive to six months before you enrolled.

Late Enrollment When You Do Have To Pay a Part A Monthly Premium

In this case, it’s a little more complicated because people who owe a Part A premium must also enroll in Part B. Once your Initial Enrollment Period ends, you have limited times of the year when you’re allowed to enroll in Part B (and thus Part A).

You can sign up during the General Enrollment Period that runs from January 1 to March 31 each year.
You can sign up during a Special Enrollment Period that you’re granted, for example, because you lost group health coverage from an employer.

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Open Enrollment for Medicare Part A

If you switch from Original Medicare to a Medicare Advantage plan, you may want to go back to Original Medicare at some point. Medicare’s Open Enrollment Period (sometimes called the Annual Enrollment Period) is one of your chances to do so.

Held each year from October 15 to December 7, this enrollment window is often used by Medicare Advantage beneficiaries to change their Part C plans for the upcoming calendar year. But if you have Part C and want to go back to Original Medicare, you’re eligible to enroll in Medicare Parts A and B again, and you can also join a standalone Medicare Part D prescription drug plan. This coverage will go into effect January 1 of the following year.

FAQs

How much is the Part A monthly premium?

If you have Medicare Part A eligibility but haven’t paid Medicare taxes through an employer for at least 10 years (40 quarters), the monthly premium for 2025 is:

$285 if you’ve paid Medicare taxes for 30-39 quarters.
$518 if you’ve paid Medicare taxes for less than 30 quarters.

In order to carry Part A if you’re among those who have to pay a monthly premium, you also have to carry Part B ($185 monthly premium in 2025). If you owe a monthly premium for Part A but delay enrollment beyond your Initial Enrollment Period, you could face a late enrollment penalty.

How much is the Part A late enrollment penalty?

If you have to pay a Part A monthly premium because of your work history and you don’t have a reason for delaying enrollment in Part A that creates a Special Enrollment Period, then you may have to pay a late enrollment penalty if you wait until after age 65 to first enroll in Part A.

For every year you didn’t enroll, you will have a 10% penalty added to your Part A premium for two years.
So, if you delayed enrollment for three years for example, you’ll have a 30% penalty added to your Part A premium for six years.

Is it possible to be eligible for Part A before age 65?

There are a few specific situations where you have Medicare Part A eligibility regardless of age:

If you have collected Social Security disability benefits for 24 months, you are eligible. If you are approved for Social Security disability because you’ve been diagnosed with Amyotrophic Lateral Sclerosis (also known as Lou Gehrig’s disease), you can enroll in Part A the first month you are approved for Social Security disability.
If you have end-stage renal disease, you can enroll in Part A on the first day of your fourth month of dialysis.

Can you get Part D if you only have Part A?

You can add a Medicare Part D prescription drug plan if you only have Part A. In order to switch to a Medicare Advantage Prescription Drug plan, you must first join both Part A and Part B.

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