Medicare Part A: What It Is, How It Works

What Is Medicare Part A?

Medicare Part A is one of four components of the federal government’s health insurance program for older adults and other eligible people. Medicare Part A helps pay for bills related to inpatient hospital stays and procedures; inpatient care in a skilled nursing facility; hospice care; and home health care.

It covers expenses such as semi-private rooms at skilled nursing facilities as well as inpatient care, supplies, and drugs during a hospital stay. Physical and occupational therapy in your home if you are homebound is also covered. For terminally ill patients, doctor’s services, medication, and grief-and-loss counseling for the families are covered.

Understanding Medicare Part A

Medicare Part A, which is also known as Medicare hospital coverage, pays for care at a hospital, skilled nursing facility, or nursing home, and for home health services. Enrollees who paid Medicare taxes during their working years or people whose spouses paid these taxes don’t pay premiums for Medicare Part A once they’re 65 years old. This means you've already paid your premiums through the 1.45% Medicare payroll tax that you and your employer each paid on all of your wages.

If you didn’t pay this tax during your working years, you do pay premiums—as much as $518 per month in 2025. Younger people who receive long-term Social Security disability benefits also qualify for premium-free Part A. However, even when Medicare Part A is premium-free, most people will still have out-of-pocket expenses for copayments and coinsurance.

Medicare Part A Eligibility

In general, you're eligible for Medicare Part A if you meet the citizenship and residency requirements and you:

• Are age 65 or older.
• Get disability benefits from Social Security or the Railroad Retirement Board for at least 25 months.
• Get disability benefits because you have amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease.
• Have end-stage renal disease (ESRD) and meet certain requirements.

How To Sign Up for Medicare Part A

Many people are automatically enrolled when they qualify, while others have to sign up for it. In general, it depends on whether you're receiving Social Security benefits. You may, for example, be enrolled automatically in Medicare Part A and Medicare Part B if you:

• Have received benefits from Social Security or the Railroad Retirement Board for at least four months before you turn 65.
• Have received Social Security benefits for at least 24 months.
• Have ALS. You will automatically get Medicare Parts A and B when your disability benefits start.

If you have ESRD, you're eligible for Medicare and can enroll in Parts A and B or a Medicare Advantage plan. If you choose Original Medicare (Parts A and B), you will need both parts to get the full benefits available with Medicare to cover certain dialysis and kidney transplant services. If you're interested in a Medicare Advantage Plan, be sure to check that the health care providers you currently see or want to see in the future, are in the plan's network.

If you aren't automatically enrolled in Medicare and you'll be eligible when you turn 65, you should sign up through Social Security during your initial enrollment period. This is a seven-month period that:

• Starts three months before the month you turn 65.
• Includes the month you turn 65.
• Ends three months after the month you turn 65.

Enrollment can be done online, by phone, or at a Social Security office.

Special Considerations for Medicare Part A

Although Medicare Part A covers many hospital-related services, it doesn’t cover everything. Providers must ask patients to sign a notice before receiving treatment when a service may not be covered. This procedure allows the patient to choose whether to accept the service and pay for it out of pocket or to refuse the service.

To be proactive about keeping your medical bills down, it’s a good idea to find out before using a Part A service if Medicare will cover all, part, or none of the cost. If Medicare won’t cover enough of the expense, find out why. There may be an alternative that is covered that would still help you, or you can file an appeal to try to get the coverage decision changed in your favor.

The three reasons why Medicare Part A might not cover something are:

• General federal and state laws
• Specific federal laws about what Medicare covers
• Local Medicare claims processors’ assessment of whether a service is medically necessary

One example of a service Medicare does not usually cover is custodial care in a skilled nursing facility—help with basic activities of daily living, such as getting dressed, bathing, and eating—if it’s the only care you need. You must have more serious medical needs for Medicare to cover your stay at a nursing home.