Who Can Get Medicare? Your Guide to Age and Disability Eligibility

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Medicare is the United States’ federal health insurance program, providing essential health coverage for millions of Americans. The program primarily serves people aged 65 and older, but also covers younger individuals with certain disabilities or specific medical conditions like End-Stage Renal Disease (ESRD) or Amyotrophic Lateral Sclerosis (ALS).

Eligibility depends on factors such as age, Medicare tax payments through employment (yours or a spouse’s), disability status, and U.S. citizenship or legal residency status.

This guide explains Medicare eligibility rules using information from official government sources including Medicare.gov and SSA.gov.

What is Medicare? A Quick Overview

Official Definition and Purpose

Medicare is federal health insurance designed for people age 65 or older, certain individuals under 65 with disabilities, and people of any age diagnosed with End-Stage Renal Disease or Amyotrophic Lateral Sclerosis.

The program helps beneficiaries manage healthcare costs, though it doesn’t cover all medical expenses and notably excludes most long-term care costs.

Medicare covered over 66.7 million people in 2023, with total expenditures exceeding $1 trillion. The program is funded through dedicated trust funds primarily supported by payroll taxes, premiums, and other sources.

The Different Parts of Medicare

Understanding Medicare’s structure helps clarify eligibility, which initially relates to Parts A and B:

Original Medicare: The traditional health plan managed by the federal government consists of two parts:

• Part A (Hospital Insurance): Covers inpatient care in hospitals, care in skilled nursing facilities (following a qualifying hospital stay), hospice care, and some home health care services. Eligibility for premium-free Part A is typically linked to work history.
• Part B (Medical Insurance): Covers medically necessary services from doctors and other healthcare providers, outpatient care, durable medical equipment, some home health care, and many preventive services like screenings and vaccines. Part B typically requires a monthly premium.

Medicare Advantage (Part C): Offered by private insurance companies approved by Medicare, these plans provide an alternative way to receive Part A and Part B benefits. They often include prescription drug coverage and may offer extra benefits like vision or dental care, usually within a specific provider network. To join a Medicare Advantage plan, you generally need to be enrolled in both Part A and Part B.

Part D (Prescription Drug Coverage): Helps cover prescription medication costs. This coverage is available through standalone Part D plans (added to Original Medicare) or included in many Medicare Advantage plans. Enrollment generally requires having either Part A or Part B.

Medicare Supplement Insurance (Medigap): Sold by private companies, Medigap policies help pay some out-of-pocket costs associated with Original Medicare, such as deductibles and coinsurance. These policies only work with Original Medicare, not Medicare Advantage.

Understanding these parts is essential because eligibility pathways, particularly the work history requirements for avoiding Part A premiums, focus primarily on securing Part A and Part B first. These initial eligibility determinations then enable access to other coverage options like Medicare Advantage or Part D.

Are You Eligible for Medicare Based on Age?

The most common Medicare eligibility pathway is reaching a specific age, along with meeting residency and (for premium-free coverage) work history requirements.

Turning 65

Reaching age 65 is the primary trigger for Medicare eligibility for most Americans. Enrollment timing revolves around this milestone.

The Initial Enrollment Period (IEP) is a 7-month window starting 3 months before your 65th birthday month, including your birthday month, and ending 3 months after.

While the full retirement age for Social Security benefits has increased beyond 65 for many, the Medicare eligibility age remains 65. You should typically sign up for Medicare during your IEP, even if your full Social Security retirement age is later, to avoid potential coverage gaps or penalties.

Citizenship and Residency Rules

To qualify for Medicare based on age, you must satisfy specific citizenship or residency criteria. You must be either:

• A U.S. citizen
• A lawfully admitted noncitizen for permanent residence (green card holder) who has lived continuously in the United States for at least 5 years immediately before applying for Medicare

This 5-year continuous residency requirement for legal permanent residents is a significant condition. For Medicare purposes, the “United States” includes the 50 states, the District of Columbia, Puerto Rico, the U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands.

Work History Requirement for Premium-Free Part A

While meeting age and residency requirements makes you eligible for Medicare, whether Part A comes with a monthly premium depends on your work history – specifically, whether you paid Medicare taxes.

What is “Sufficient Work History?” Generally, you qualify for premium-free Part A if you or your spouse worked for at least 10 years (40 quarters) in jobs where Medicare taxes were paid. This work doesn’t need to be continuous. Work performed in government jobs where Medicare taxes were paid also counts toward this requirement.

Having this work history means you avoid paying a monthly premium for Part A coverage. This structure positions premium-free Part A largely as a benefit earned through workforce participation and Medicare tax contributions, rather than a program based solely on need.

Qualifying Through Your Spouse’s Work: Many people who don’t have the required 40 quarters of Medicare-covered work themselves can still qualify for premium-free Part A based on their spouse’s work record. This reflects a system design acknowledging economic interdependence within marriage.

Eligibility through a spouse is possible if the spouse has the necessary 40 quarters and is eligible for Social Security or Railroad Retirement Board (RRB) benefits, under these circumstances:

• Current Spouse: You are married to a living spouse who meets the work requirements.
• Deceased Spouse: You were married to the worker for at least 9 months (with some exceptions) before their death and generally haven’t remarried before age 60 (or age 50 if disabled). The rules allowing remarriage after age 60 (or 50 if disabled) without losing eligibility provide some flexibility while still tying eligibility to marital history.
• Divorced Spouse: You were married to the worker for at least 10 years, are currently unmarried, and your ex-spouse is at least 62 years old and eligible for Social Security or RRB benefits. (Your ex-spouse doesn’t need to be actively receiving benefits for you to qualify for Medicare.) The 10-year marriage duration is a key threshold for divorced individuals.
• Dependent Parent: In rarer cases, a dependent parent might qualify for premium-free Part A based on the work record of their fully insured deceased child.

These spousal provisions significantly expand access to premium-free Part A, ensuring that individuals with interrupted careers (perhaps due to caregiving) can still benefit from their spouse’s work history.

Are You Eligible for Medicare Due to Disability (Under 65)?

Medicare isn’t just for those 65 and older. Younger individuals can qualify if they meet the standard citizenship and residency requirements and have received disability benefits for a specific duration or have certain severe medical conditions.

Receiving Social Security Disability Insurance (SSDI)

Individuals under 65 generally become eligible for Medicare after they’ve been entitled to receive SSDI benefits for 24 months. Enrollment in both Part A and Part B is typically automatic, starting in the 25th month of disability benefit entitlement. A welcome package with a Medicare card is mailed about 3 months before coverage begins.

This 24-month waiting period applies to those qualifying for SSDI based on their own work record, as well as those receiving benefits as a disabled widow or widower (age 50 or older) or as a disabled adult child (disability began before age 22) based on a parent’s or spouse’s record.

The clock for the 24-month wait starts from the date of entitlement to disability benefits, which might be earlier than the date the first payment is received. Under certain rules, months from a previous period of disability may count toward the 24-month requirement if the current disability is related or begins within a specific timeframe (e.g., 5 years for disabled workers) after the prior entitlement ended.

The 24-month waiting period represents a significant hurdle for many individuals becoming disabled, as they may lose employer-sponsored health insurance long before Medicare coverage begins. This policy likely reflects both cost-containment considerations and an attempt to ensure the disability is long-term before granting Medicare eligibility, but it creates a notable coverage gap.

Having End-Stage Renal Disease (ESRD)

Individuals of any age can qualify for Medicare if they have ESRD, meaning permanent kidney failure that requires regular dialysis or a kidney transplant. In addition to the medical condition, you (or your spouse, or sometimes a parent for a dependent child) must meet certain work history requirements:

• Have worked the required amount of time paying Medicare taxes under Social Security, the RRB, or as a government employee; OR
• Be already getting or eligible for Social Security or RRB benefits

Coverage Start: The timing for ESRD-based Medicare coverage is unique.

• For individuals on dialysis, coverage usually starts on the first day of the fourth month of treatments. This waiting period begins even if the application for Medicare is filed later.
• Coverage can start as early as the first month of dialysis if you participate in a certified home dialysis training program during the first three months and are expected to complete it.
• For individuals receiving a kidney transplant, coverage can begin as early as the month you’re admitted to a Medicare-certified hospital for the transplant (or pre-transplant services), provided the transplant occurs that month or within the following two months.

Coverage End: If Medicare eligibility is based solely on ESRD, the coverage ends:

• 12 months after the month dialysis treatments stop
• 36 months after the month of a successful kidney transplant

Coverage can restart if dialysis or another transplant becomes necessary within these timeframes. A separate, limited benefit exists to help cover immunosuppressive drugs beyond the 36-month post-transplant period for those without other qualifying health coverage.

Coordination with Other Insurance: A special 30-month coordination period applies when an individual with ESRD also has group health plan coverage (like from an employer). During this period, which starts when Medicare eligibility begins (usually the 4th month of dialysis), the group health plan pays first, and Medicare pays second. After 30 months, Medicare becomes the primary payer.

Having ALS (Amyotrophic Lateral Sclerosis / Lou Gehrig’s Disease)

Individuals diagnosed with ALS who are entitled to SSDI benefits receive expedited access to Medicare. Due to specific legislation (Public Law 106-554), the standard 24-month Medicare waiting period is waived for these individuals. Medicare coverage (Part A and Part B) begins automatically in the very first month they are entitled to receive SSDI benefits.

Furthermore, additional legislation (Public Law 116-250) eliminated the 5-month waiting period for SSDI cash benefits for ALS claimants approved on or after July 23, 2020.

This special handling of ALS reflects a policy decision to grant immediate access to Medicare for individuals with this specific, rapidly progressive condition, contrasting sharply with the standard 24-month wait for most other disabilities qualifying through SSDI.

Table 1: Quick Guide to Medicare Eligibility Pathways

Eligibility Without Enough Work History: Buying Medicare Part A

Not everyone meets the 40-quarter work history requirement for premium-free Part A through their own record or a spouse’s. However, these individuals may still be able to enroll in Medicare Part A by paying a monthly premium, provided they meet certain criteria.

Who Can Buy Part A?

You may be eligible to purchase Part A if you satisfy all the following conditions:

• Are age 65 or older
• Meet the Medicare citizenship or residency requirements (U.S. citizen, or a legal permanent resident who has lived continuously in the U.S. for 5 or more years)
• Are enrolled, or are enrolling, in Medicare Part B (Medical Insurance)

This option may also be available to certain individuals under 65 with disabilities whose premium-free Part A coverage ended because they returned to work.

The requirement to enroll in Part B (which also has a premium) in order to buy Part A means those without the requisite work history face a combined premium cost for both hospital and medical insurance coverage. This structure underscores the significant financial advantage of qualifying for premium-free Part A through work history and highlights the potential burden for those who must buy into the program.

How Much Does Part A Cost if You Buy It? (2025 Premiums)

The monthly premium amount for Part A depends on the amount of time you or your spouse paid Medicare taxes:

Table 2: Buying Medicare Part A – Monthly Premium Costs (2025)

Source: Based on 2025 figures from Medicare.gov. Note: Must also enroll in Part B. Late enrollment penalty may apply.

Late Enrollment Penalty for Purchased Part A: If you’re required to buy Part A but don’t enroll when first eligible (typically during your Initial Enrollment Period), you may face a late enrollment penalty. Your monthly premium could increase by 10%. This higher premium must be paid for twice the number of years you could have had Part A but delayed enrollment.

For example, delaying enrollment for 2 years could mean paying the 10% penalty for 4 years. This penalty usually doesn’t apply if you qualify for a Special Enrollment Period.

Help Paying Your Premiums: Recognizing the potential cost barrier for individuals who must buy Part A, assistance programs are available. State-run Medicare Savings Programs (MSPs) can help people with limited income and resources pay for Medicare costs.

Specifically, the Qualified Medicare Beneficiary (QMB) program can pay the Part A premium (as well as Part B premiums and other cost-sharing) for eligible individuals. Application for these programs is made through the state Medicaid agency.

The existence of these programs provides a crucial safety net but requires individuals to navigate an additional application process at the state level.

How to Check Eligibility and Apply for Medicare

Navigating the Medicare enrollment process involves understanding which government agency is responsible and whether enrollment happens automatically or requires action.

Who Handles Eligibility?

The Social Security Administration (SSA) is the agency responsible for determining eligibility and processing applications for Original Medicare (Part A and Part B).

While the Centers for Medicare & Medicaid Services (CMS) administers the overall Medicare program, SSA serves as the primary point of contact for enrollment into the foundational parts of Medicare.

For individuals with work history tied to the railroad industry, the Railroad Retirement Board (RRB) manages their Medicare enrollment.

Automatic Enrollment vs. Active Application

A critical distinction exists between those who get Medicare automatically and those who must actively apply:

Automatic Enrollment: Enrollment in both Part A and Part B generally happens automatically for individuals who are already receiving Social Security retirement or disability benefits (or RRB benefits) for at least four months before turning 65. It’s also automatic for those who have received SSDI benefits for 24 months, and for individuals with ALS as soon as their SSDI benefits begin.

These individuals will receive a “Welcome to Medicare” package including their Medicare card about three months before coverage starts, without needing to file an application.

Exception: Residents of Puerto Rico or foreign countries are generally not automatically enrolled in Part B even if they get Part A automatically; they must actively elect Part B coverage.

Active Application Required: Individuals must take action to enroll if they are approaching age 65 but are not yet receiving Social Security or RRB benefits. Active application is also necessary for those who need to buy Part A because they lack sufficient work history, and generally for those qualifying based on ESRD (unless they were already receiving disability benefits).

This difference is crucial; individuals who mistakenly assume they will be automatically enrolled when they are required to apply risk missing their enrollment window, potentially leading to coverage gaps and lifelong late enrollment penalties.

Ways to Apply

For those who need to apply actively, the SSA offers several methods:

Online: Considered the easiest and fastest method, applications can be submitted through the SSA website or Medicare sign-up page. Individuals can apply for Medicare only, even if they are not yet ready to claim Social Security retirement benefits. Creating a secure my Social Security account online is typically required for the online application.

Phone: Individuals can apply by calling the SSA toll-free at 1-800-772-1213 (TTY: 1-800-325-0778).

In Person: Applications can be made at a local Social Security office. It is advisable to call ahead to make an appointment.

RRB: Those qualifying through railroad employment should contact the RRB at 1-877-772-5772.

Information Needed to Apply

When applying, it is helpful to have certain information readily available, such as:

• Date and place of birth
• Social Security number
• Citizenship status
• Information about current or former spouses (including marriage/divorce dates)
• Details about any current group health plan coverage
• Potentially work history information

For online applications, a valid email address may be needed, especially when applying for Part B only.

Online Eligibility Tools

To help individuals estimate their eligibility and potential premium costs, online tools are available:

Medicare.gov Eligibility & Premium Calculator: This tool on the official Medicare website can provide estimates of eligibility timing and premium amounts.

SSA.gov Benefit Eligibility Tools: The Social Security website offers various calculators and a Benefit Eligibility Screening Tool (BEST). While primarily focused on cash benefits (retirement, disability, survivors), these tools can indirectly help assess factors related to Medicare eligibility, like potential entitlement to SSDI or retirement benefits which often trigger Medicare enrollment.

Key Medicare Eligibility Terms You Should Know

Understanding the language used by Medicare and Social Security is essential for navigating eligibility rules. Here are definitions for some common terms:

Premium-Free Part A: Medicare Part A (Hospital Insurance) coverage for which you don’t have to pay a monthly premium. It’s typically earned by having worked and paid Medicare taxes for a sufficient period (usually 40 quarters or about 10 years), either through your own employment or through a spouse’s work record.

Work Credits / Quarters of Coverage: The building blocks Social Security uses to determine eligibility for Social Security benefits and premium-free Medicare Part A. You earn credits by working and paying Social Security and Medicare taxes. Generally, 40 credits are needed to qualify for premium-free Part A.

Medicare Taxes: Payroll taxes mandated by the Federal Insurance Contributions Act (FICA) paid by employees, employers, and self-employed individuals. These taxes specifically fund Medicare Part A (Hospital Insurance).

Social Security Disability Insurance (SSDI): A federal insurance program managed by the Social Security Administration that pays monthly benefits to people who are unable to work for a year or more because of a disability. Receiving SSDI benefits typically leads to Medicare eligibility after a 24-month waiting period.

End-Stage Renal Disease (ESRD): Permanent kidney failure that requires a regular course of dialysis or a kidney transplant. ESRD is a qualifying condition for Medicare coverage, regardless of age, provided other requirements (like a work history connection) are met.

Amyotrophic Lateral Sclerosis (ALS) / Lou Gehrig’s Disease: A specific progressive neurodegenerative disease. Individuals diagnosed with ALS who are entitled to SSDI benefits qualify for Medicare coverage starting the same month their disability benefits begin, bypassing the usual 24-month waiting period.

Lawfully Admitted for Permanent Residence: An immigration status granted to non-citizens allowing them to live and work permanently in the U.S. (often evidenced by a “green card”). To qualify for Medicare, permanent residents generally must also meet a 5-year continuous residency requirement.

Initial Enrollment Period (IEP): The primary 7-month window to sign up for Medicare Part A and Part B when first eligible. For most, this period surrounds their 65th birthday (3 months before, the month of, and 3 months after). For those qualifying through disability, it typically occurs around the 25th month of receiving disability benefits.

Special Enrollment Period (SEP): An opportunity to enroll in Medicare Part A and/or Part B outside of the standard IEP or General Enrollment Period. SEPs are triggered by specific life events, such as losing health coverage from a current employer.

General Enrollment Period (GEP): A set time each year, from January 1 through March 31, when individuals who missed their IEP and do not qualify for an SEP can enroll in Medicare Part A (if buying it) and/or Part B. Coverage begins July 1st of that year. Late enrollment penalties may apply.

Premium: The regular, typically monthly, payment required to maintain insurance coverage.

Deductible: The amount you must pay out-of-pocket for covered healthcare services or prescriptions before your Medicare plan begins to pay.

Coinsurance: The percentage share of the cost for a covered healthcare service that you pay after meeting your deductible (e.g., typically 20% for most Part B services under Original Medicare).

Benefit Period: The way Original Medicare measures the use of inpatient hospital and skilled nursing facility (SNF) services. A benefit period begins on the day of admission as an inpatient and ends after you’ve been out of the hospital or SNF for 60 consecutive days. There is no limit to the number of benefit periods you can have, but a new Part A deductible applies for each new benefit period.

Medicare Savings Program (MSP): Programs administered by states that help individuals with limited income and resources pay some or all of their Medicare costs, such as premiums, deductibles, and coinsurance. Examples include the QMB, SLMB, QI, and QDWI programs.

Our articles make government information more accessible. Please consult a qualified professional for financial, legal, or health advice specific to your circumstances.