Original Medicare (Part A and B) Eligibility and Enrollment

This page contains information on Medicare Part A and Medicare Part B eligibility and enrollment.  For more information about Medicare for people who are still working, go to our Employer page or I’m 65 and Still Working page. 

Medicare Part A (Hospital Insurance) and Medicare Part B (Medical Insurance) are available to the individuals below:

• Age 65 or older  
• Disabled
• End-Stage Renal Disease (ESRD)

Medicare Part A (Hospital Insurance)

Most people get Part A for free, but some have to pay a premium for this coverage.

To be eligible for premium-free Part A, an individual must be entitled to receive Medicare based on their own earnings or those of a spouse, parent, or child. To receive premium-free Part A, the worker must have a specified number of quarters of coverage (QCs) and file an application for Social Security or Railroad Retirement Board (RRB) benefits. The exact number of QCs required is dependent on whether the person is filing for Part A on the basis of age, disability, or End Stage Renal Disease (ESRD). QCs are earned through payment of payroll taxes under the Federal Insurance Contributions Act (FICA) during the person's working years. Most individuals pay the full FICA tax so the QCs they earn can be used to meet the requirements for both monthly Social Security benefits and premium-free Part A.

NOTE: Certain Federal, State, and local government employees pay only the Part A portion of the FICA tax. The QCs they earn can be used only to meet the requirements for premium-free Part A; they may not be used to meet the requirements for monthly Social Security benefits.

Premium-Free Medicare Part A Based on Age

To be eligible for premium-free Part A on the basis of age:

• A person must be age 65 or older; and
• Be eligible for monthly Social Security or Railroad Retirement Board (RRB) cash benefits.

An individual who is receiving monthly Social Security or RRB benefits, at least 4 months prior to turning age 65, does not need to file a separate application to become entitled to premium-free Part A.  In this case, the individual will get Part A automatically at age 65. 

An individual who is not receiving monthly Social Security or RRB benefits must file an application for Medicare by contacting the Social Security Administration.

Part A coverage begins the month the individual turns age 65, provided he or she files an application for Part A (or for Social Security or RRB benefits) within 6 months of the month in which he or she becomes age 65. If the application is filed more than 6 months after turning age 65, Part A coverage will be retroactive for 6 months.

NOTE: For an individual whose 65th birthday is on the first day of the month, Part A coverage begins on the first day of the month preceding their birth month. For example, if an individual's birthday is on December 1, Part A begins on November 1.

Medicare Part A Based on Age for People Who Must Pay a Premium

People who must pay a premium for Part A do not automatically get Medicare when they turn 65. They must:

• File an application to enroll by contacting the Social Security Administration;
• Enroll during a valid enrollment period; and
• Also enroll in or already have Part B. 

To keep premium Part A, the person must continue to pay all monthly premiums and stay enrolled in Part B. This means that the person must pay both the premium for Part B and the premium for Part A timely to keep this coverage.   

Premium Part A coverage begins the month following the month of enrollment.

Medicare Based on Disability  

A person who is entitled to monthly Social Security or Railroad Retirement Board (RRB) benefits on the basis of disability is automatically entitled to Part A after receiving disability benefits for 24 months. Disabled federal, state and local government employees who are not eligible for monthly Social Security or RRB benefits may get deemed entitlement to disability benefits and automatically entitled to Part A after being disabled for 29 months.

Special Rule for People with Amyotrophic Lateral Sclerosis (ALS) (Lou Gehrig’s disease)

Individuals whose disability is Amyotrophic Lateral Sclerosis (ALS) are entitled to Part A the first month they are entitled to Social Security or RRB disability cash benefits. There is no waiting period.

Special Rule for People Claiming Child Disability Benefits

SSA rules do not allow for child disability benefits to begin earlier than age 18. Therefore, Part A entitlement based on child disability benefit entitlement can never begin before the month the person attains age 20 (or age 18 if the individual’s disability is ALS).

Medicare Based on End-Stage Renal Disease (ESRD)

Individuals are eligible for premium-free Part A if they receive regular dialysis treatments or a kidney transplant, have filed an application for Medicare, and meet one of the following conditions:

• Have worked the required amount of time under Social Security, the Railroad Retirement Board (RRB), or as a government employee; or
• Are getting or are eligible for Social Security or RRB benefits; or
• Are the spouse or dependent child of a person who has worked the required amount of time under Social Security, the RRB, or as a government employee; or are getting Social Security or RRB benefits.

Part A coverage begins:

• The 3rd month after the month in which a regular course of dialysis begins; or
• The first month a regular course of dialysis begins if the individual engages in self-dialysis training; or
• The month of kidney transplant; or
• Two months prior to the month of transplant if the individual was hospitalized during those months in preparation for the transplant

Medicare Part B (Medical Insurance)

Individuals already receiving Social Security or RRB benefits at least 4 months before being eligible for Medicare and residing in the United States (except residents of Puerto Rico) are automatically enrolled in both premium-free Part A and Part B. People who are automatically enrolled have the choice of whether they want to keep or refuse Part B coverage. People living in Puerto Rico who are eligible for automatic enrollment are only enrolled in premium-free Part A; they must actively enroll in Part B to get this coverage.

Individuals who are not receiving a Social Security or RRB benefit are not automatically enrolled. Individuals who previously refused Part B, or who terminated their Part B enrollment, may enroll (or re-enroll) in Part B only during certain enrollment periods. In most cases, if someone does not enroll in Part B when first eligible, they will have to pay a late enrollment penalty for as long as they have Part B.

Part B is a voluntary program that requires the payment of a monthly premium for all parts of coverage. Eligibility rules for Part B depend on whether a person is eligible for premium-free Part A or whether the individual has to pay a premium for Part A coverage.

Individuals who are eligible for premium-free Part A are also eligible for enroll in Part B once they are entitled to Part A.

Individuals who must pay a premium for Part A must meet the following requirements to enroll in Part B:

• Be age 65 or older;
• Be a U.S. resident; AND
• Be either a U.S. citizen, OR
• Be an alien who has been lawfully admitted for permanent residence and has been residing in the United States for 5 continuous years prior to the month of filing an application for Medicare.

NOTE: Individuals who were terminated from Part A 36 months after receiving a kidney transplant may be eligible for the Part B Immunosuppressive Drug benefit. Learn more about Part B Immunosuppressive Drug Coverage.

Enrollment Periods and When Coverage Begins

Individuals eligible for premium-free Part A, who are not automatically enrolled, can enroll in Part A at any time after they are first eligible for the coverage.

Individuals who want premium Part A, Part B or both may only enroll during certain enrollment periods that are outlined in law. The following enrollment periods apply to both premium Part A and Part B:

• Initial Enrollment Period;
• General Enrollment Period;
• Special Enrollment Period for

Initial Enrollment Period (IEP)

The IEP is a 7-month period that begins 3 months before the month a person turns 65, their birthday month and ends 3 months after the person turns 65. For someone under age 65 who becomes entitled to Medicare based on disability, entitlement begins with the 25^th month of disability benefit entitlement. For these individuals, the IEP begins 3 months before the 25^th month of disability benefit entitlement, includes the 25^th month, and ends three months after. The IEP for people with ESRD and ALS varies based on their situation.

Coverage will begin the month after a person enrolls during their IEP. Disabled individuals are automatically enrolled in Medicare Part A and Part B after they have received disability benefits from Social Security for 24 months.

NOTE: In most cases, if someone does not enroll in Part B or premium Part A when first eligible, they will have to pay a late enrollment penalty. The Part B penalty is assessed for as long as the person has Part B. 

General Enrollment Period (GEP)

The GEP is a 3-month period that takes place from January 1 through March 31 of each year. Part B and premium Part A coverage will begin the month after a person enrolls during the GEP.

Special Enrollment Period (SEP)

There are certain situations when a person can sign up for Part B (and Premium Part A) during a Special Enrollment Period without paying a late enrollment penalty. A Special Enrollment Period is only available for a limited time. If the person doesn’t sign up during their Special Enrollment Period, they’ll have to wait for the next General Enrollment Period and they might have to pay a monthly late enrollment penalty.

Coverage will begin the month after a person enrolls during their SEP.

SEP for the Working Aged and Working Disabled

Individuals who do not enroll in Part B or premium Part A when first eligible because they were covered under a group health plan based on their own or a spouse's current employment (or the current employment of a family member, if disabled) may enroll during this SEP.

The individual can enroll at any time while covered under the group health plan based on current employment, or during the 8-month period that begins the month the employment ends or the group health plan coverage ends, whichever comes first.

NOTE: Individuals with ESRD are not eligible to enroll using this SEP.

SEP for International Volunteers

Individuals who do not enroll in Part B or premium Part A when first eligible because they were performing volunteer service outside of the United States for at least 12 months on behalf of a tax-exempt organization and had health insurance that provided coverage for the duration of the volunteer service may enroll using this SEP.

The SEP is a 6-month period that begins the earlier of the first day of the month following the month for which the:

• individual was no longer serving as a volunteer outside of the United States;
• organization no longer has tax-exempt status; or
• individual no longer has health insurance that provides coverage outside of the United States.

SEP for Certain TRICARE Beneficiaries

Individuals who enroll in Part A based on disability or ESRD, but do not enroll in Part B because they were eligible for TRICARE standard or TRICARE prime, may enroll using this SEP.

Eligible individuals are those who are:

• Under age 65, and
• Eligible for TRICARE Standard at the time of Part A entitlement and:
• A military retiree or military retiree family member, or
• On active duty or a family member of an active duty service member with Medicare based on ESRD.

Eligible individuals may enroll:

• If notified of Medicare entitlement during the IEP -The month after the end of the IEP, or
• If notified of Medicare entitlement after the IEP -The month of notification of Medicare entitlement.

Coverage begins:

If notified of Medicare entitlement during the IEP:

• The month of enrollment, or
• The first month after the end of the IEP

If notified of Medicare entitlement after the IEP:

• The month of enrollment, or
• The month Part B terminated based on the refusal.

If entitlement is based on ESRD, coverage begins

• The month of Part A entitlement, or
• The month of enrollment, or
• The month after the end of the IEP.

Special Enrollment Period for Exceptional Conditions

Effective January 1, 2023, the following SEPs for exceptional conditions are available for premium Part A and Part B, respectively:

SEP for Individuals Impacted by an Emergency or Disaster

Individuals who do not enroll in Part B or premium Part A when first eligible due to having an emergency or disaster declared by a federal, state, or local government entity in their area may enroll using this SEP.

If a person is eligible because they were impacted by an emergency or disaster, they can sign up as early as the month of the emergency or disaster, or up to six months after the emergency or disaster has ended. They may also be able to use this SEP if the disaster or emergency takes place where their authorized representative, legal guardian, or person who makes health care decisions on their behalf resides.

The SEP begins the date an emergency or disaster is declared, or the start date identified in the emergency declaration, whichever is earlier. The SEP ends six months after the later of:

• The end date identified in the disaster or emergency declaration, or
• The end date of any extensions or the date when the declaration has been determined to have ended or has been revoked, or
• The date of the declaration, if such date is after the end of the disaster.

Medicare benefits will be effective the first day of the month following enrollment.

SEP for Health Plan or Employer Misrepresentation

Individuals who do not enroll in Part B or premium Part A when first eligible due to misrepresentation or reliance on incorrect information provided by their employer or group health plan (GHP), agents or brokers of health plans, or any person authorized to act on behalf of such entity may enroll using this SEP.

An eligible person must demonstrate (by documentation or written attestation) both of the following:

• They did not enroll in part B or premium Part A during an enrollment period in which they were eligible based on information received from an employer or GHP, agents or brokers of health plans, or any person authorized to act on such organization’s behalf. 
• An employer, GHP, agent or broker of a health plan, or their representative materially misrepresented information or provided incorrect information relating to enrollment in part B or premium Part A.

This SEP begins the day an individual notifies the Social Security Administration and ends six months later. 

Medicare benefits will be effective the first day of the month following enrollment. 

SEP for Formerly Incarcerated Individuals

Individuals who do not enroll in Part B or premium Part A when first eligible because they were incarcerated may enroll using this SEP.

If a person is eligible because they are not enrolled in Medicare due to being incarcerated, they can sign up anytime within the first 12 months after their release from incarceration.

• This SEP begins the day an individual is released from the custody of penal authorities and ends the last day of the 12^th month after that release.
• Individuals have the option to select a retroactive effective date (not to begin prior to their release date and not to exceed 6 months). If individuals choose this retroactive option, they will be responsible for paying Medicare premiums back to the date of coverage.
• Medicare benefits will be effective the first day of the month following enrollment, or up to 6 months retroactive, if the beneficiary, chooses retroactive coverage.

SEP to Coordinate with Termination of Medicaid Coverage

Individuals whose Medicaid eligibility terminated may enroll using this SEP.

A person may be eligible if they have lost Medicaid entirely, missed a Medicare enrollment period and their Medicaid coverage was terminated on or after January 1, 2023. 

• The SEP begins when an individual is notified of an upcoming termination of Medicaid eligibility and ends six months after the Medicaid termination.
• Medicare benefits start the month after Medicare enrollment unless the individual elects a start date back to the first day of the month the individual lost Medicaid and agrees to pay all prior premiums.

NOTE: Individuals who still are eligible for Medicaid, including a Medicare Savings Program, and have not received notice of an upcoming Medicaid termination are not eligible for this SEP. 

SEP for Other Exceptional Conditions

Individuals who do not enroll in Part B or premium Part A when first eligible because conditions beyond their control caused them to miss an enrollment period may enroll using this SEP. This SEP is available for individuals whose unique conditions do not qualify for other SEPs. An eligible person must demonstrate (by documentation or written attestation) that conditions outside of their control that occurred on or after January 1, 2023, caused them to miss an enrollment period.

An individual’s request for this SEP will only be granted in conditions that are truly exceptional in nature, and will not be used to grant individual’s enrollment due to forgetfulness, lack of knowledge, or failure to make premium payments.

SSA will determine when this SEP begins on a case-by-case basis, but the SEP will end no less than 6 months after it begins. Medicare benefits will be effective the first day of the month following enrollment.

Part A and B Enrollment Forms (Downloads Below)

CMS-18-F-5: Individuals who do not have Part A and wish to enroll should complete the CMS-18-F-5 form or contact Social Security at 1-800-772-1213. This form can be used to enroll in Part B at the same time. If applying for the SEP for the Working aged and Working Disabled, also complete the form CMS-L564.

CMS-40B: Individuals who have Part A, but not Part B, should complete form CMS-40B to enroll in Part B. If applying for the SEP for the Working aged and Working Disabled, also complete the form CMS-L564.

CMS-4040: Individuals who are NOT entitled to social security or railroad retirement board benefits should complete form CMS-4040 to enroll in Part B.

CMS-43: Individuals who have ESRD should complete form CMS-43 to enroll in Part A and Part B.

CMS-10797: Individuals who qualify for a special enrollment period due to exceptional conditions should complete the CMS-10797 to enroll in premium Part A and Part B.

CMS-L564: Individuals who are applying for the SEP for the Working Aged and Working Disabled should complete the form CMS-L564 along with the applicable Part A or Part B enrollment form.

Termination of Enrollment

Individuals entitled to premium-free Part A cannot voluntarily terminate their Part A coverage. This is not permitted by law. Generally, premium-free Part A ends due to:

• Loss of entitlement to Social Security or Railroad Retirement Board benefits; or
• Death.

There are special rules for when premium-free Part A ends for people with ESRD.

Premium Part A and Part B coverage can be voluntarily terminated because premium payments are required. Premium Part A and Part B coverage ends due to:

• Voluntary disenrollment request (coverage ends prospectively);
• Failure to pay premiums;
• For individuals under age 65 (disabled and ESRD), loss of Part A entitlement (Part B terminates at the same time as Part A); or
• Death.

For individuals who want to disenroll from Premium Part A and Part B coverage, use form CMS-1763 in the downloads section of this page.  

Premiums

Premium Part A and Part B coverage requires payment of monthly premiums.

IRMAA (Income-Related Monthly Adjustment Amount)

Individuals and married couples with an income over a certain limit must pay a higher premium for Part B and an extra amount for Part D coverage in addition to their Part D plan premium. This additional amount is called income-related monthly adjustment amount. Less than 5 percent of people with Medicare are affected, so most people will not pay a higher premium. Visit the Medicare Parts A & B Income Related Adjustment Amounts page for information about income limits.

Late Enrollment Penalty (LEP) for Premium Part A

If an individual did not enroll in premium Part A when first eligible, they may have to pay a higher monthly premium if they decide to enroll later. The monthly premium for Part A may increase up to 10%. The individual will have to pay the higher premium for twice the number of years the individual could have had Part A but did not sign up.

For individuals enrolling using the SEP for the Working Aged and Working Disabled, the premium Part A LEP is calculated by adding the months that have elapsed between the close of the individual’s IEP and the end of the month in which the individual enrolls. For enrollments after your IEP has ended, months where you had group health plan coverage are excluded from the LEP calculation.

For individuals enrolling using an Exceptional Conditions SEP or the International Volunteers SEP, no LEP will be applied.

Late Enrollment Penalty (LEP) for Part B

If an individual did not sign up for Part B when first eligible, the individual may have to pay a late enrollment penalty for as long as the individual has Medicare. The individual’s monthly premium for Part B may go up 10% for each full 12-month period that the individual could have had Part B but did not sign up for it.

For individuals enrolling using the SEP for the Working Aged and Working Disabled, the Part B LEP is calculated by adding the months that have elapsed between the close of the individual’s IEP and the end of the month in which the individual enrolls. For enrollments after your IEP has ended, months where you had group health plan coverage are excluded from the LEP calculation.

For individuals enrolling using an Exceptional Conditions SEP, the International Volunteers SEP, or the SEP for Certain TRICARE Beneficiaries, no LEP will be applied.