What is Original Medicare?

Most people become eligible for Original Medicare when they turn 65. But coverage is also available to younger people if they have a qualifying disability. Eligibility begins once they have been receiving Social Security disability benefits for two years. Younger people are also eligible if they’ve been diagnosed with Amyotrophic Lateral Sclerosis (ALS) or end-stage renal disease (ESRD). (See our article about Medicare eligibility based on ALS or ESRD.)

As of April 2023, nearly 66 million people were enrolled in Medicare (roughly 34 million in Original Medicare and 32 million in Medicare Advantage). Of those enrollees, about 7.7 million were under 65 and eligible due to a disability, ALS, or ESRD. The other 58 million people were 65 or older.

Original Medicare covers most medically necessary care that beneficiaries need:

• Medicare Part A is also called hospital insurance, and it’s designed to cover inpatient care (including medications received during an inpatient stay) as well as hospice care, skilled nursing facility care, and some home health care following an inpatient or skilled nursing facility stay. Read more about Part A enrollment and costs.
• Medicare Part B covers physician services and outpatient care, covering expenses such as office visits, outpatient surgery, durable medical equipment, mental health care, certain vaccines, and certain medications that are administered in a medical office. Read more about Part B enrollment and costs.

Most medical care is covered under Medicare Part A, Part B, or a combination of the two. But although Original Medicare may cover much of the care a typical beneficiary might need, there are some notable exceptions:

• For the most part, Original Medicare does not cover prescription drugs. The exceptions are drugs that are provided during an inpatient stay, skilled nursing facility stay, or hospice care (covered under Medicare Part A), and certain medications that are administered via infusion or injection in a medical office (covered under Medicare Part B).
• Original Medicare does not cover routine dental, vision, or hearing care. So it does not provide coverage for expenses such as dental cleanings / procedures, eye glasses, or hearing aids. Treatment for certain eye diseases (e.g. cataracts or macular degeneration) is covered by Original Medicare. Cochlear implants may also be covered by Original Medicare, and so can certain dental procedures that are “closely related to other covered medical procedures.” But in general, most dental, vision, and hearing care is not covered by Original Medicare.
• Original Medicare does not cover custodial care, unless it’s being provided in conjunction with medical care (e.g., assistance with dressing and bathing while in a skilled nursing facility to recover from a hip replacement). Original Medicare will not pay for assistance with activities of daily living (ADLs). (Medicaid does provide coverage, however, and Medicare beneficiaries may also get coverage through private long-term care insurance policies.)
• Original Medicare generally does not cover routine foot care (e.g. trimming nails, removing calluses, etc.) or orthopedic shoes/inserts.
• With very limited exceptions, Original Medicare does not cover care received outside the U.S. and its territories.

As we’ll discuss in the next section, there are also out-of-pocket costs associated with covered care under Original Medicare. So even for covered services, it’s important to understand that the enrollee may still have to pay some or all of the cost. (If it’s a service covered under Part B and the enrollee has not yet paid the Part B deductible, they would have to pay all of the charge if it’s less than the Part B deductible.)

Original Medicare costs include premiums (the amount you pay to have the coverage) and out-of-pocket costs (the amount you pay for a medical procedure). Here’s how those work for both parts of Original Medicare:

Part A premiums:

Part A is a $0 premium for about 99% of Medicare beneficiaries because they or a spouse paid Medicare taxes during at least 40 quarters of work history. For the other 1% of beneficiaries, the Part A monthly premium in 2023 is $278 if they have at least 30 quarters of work history, and $506 if they have less than 30 quarters of work history.

Part A out-of-pocket expenses:

• The Part A deductible is $1,600 in 2023. (Note that this is per benefit period, as opposed to per-year.)
• If more than 60 days of inpatient care is needed, there’s a $400-per-day charge for days 61-90.
• If the patient is still hospitalized after 90 days and has lifetime reserve days available, the cost is $800 per day while lifetime reserve days are used. (Each beneficiary has a total of 60 lifetime reserve days.)
• If a beneficiary has a covered skilled nursing facility stay, the first 20 days are free but there’s a charge of $200 per day for days 21 through 100.

Part B premium:

For most beneficiaries, the Part B premium in 2023 is $164.90 a month. But some high-income beneficiaries pay more. (Learn more about this.) And on the other end of the income spectrum, some people are eligible for assistance that reduces or eliminates their Part B premiums. (See our state-by-state guide for more information about how this works.)

Part B out-of-pocket costs:

Part B has an annual deductible, which is $226 in 2023. After the beneficiary pays that amount, additional services covered by Part B are split 80/20, with Medicare paying 80% of the Medicare-approved amount, and the beneficiary paying the other 20%.

For most people, the answer to this seems to be yes. And indeed, most beneficiaries do have supplemental coverage.

Supplemental coverage is optional, but it’s important to understand that Original Medicare does not have a cap on out-of-pocket costs. This includes the 20% Part B coinsurance, which can add up to an unlimited amount. Prior to enrolling in Medicare, many people are accustomed to health insurance that does have a limit on out-of-pocket costs. (For most plans, that limit can’t be more than $9,100 for in-network care in 2023.)

And Medicare Part A does not cover unlimited days in the hospital. A 60-day benefit period is enough to cover most hospitalizations. (The average inpatient stay is about five days.) But after an inpatient stay has reached 90 days, the beneficiary is limited to a lifetime maximum of 60 additional days of coverage under Original Medicare.

So in order to minimize out-of-pocket costs under Original Medicare, many beneficiaries maintain supplemental coverage, either through a Medigap policy or an employer/union/retiree policy. Medigap policies pay benefits after Medicare has paid its share, with different benefit levels depending on the plan the person selects. With employer/union/retiree coverage, the determination of which coverage is primary and which is secondary will depend on the size of the group health plan.

Since Original Medicare does not cover most outpatient prescription drugs, it’s also important for beneficiaries to maintain drug coverage, either from employer/union/retiree policy or Medicare Part D.