Each year, the Center for Medicare and Medicare Services conducts a General Enrollment Period (GEP) from January 1 through March 31. This column discusses how federal employees and retirees are affected by the GEP.
Eligibility Requirements for Medicare Enrollment
In order for a federal employee to be eligible to enroll in Medicare when they become age 65, the employee must be “fully insured” with respect to Medicare. To be “fully insured,” the employee paid the Medicare “hospital insurance tax” (HIT) for a minimum of ten years during the employee’s working years. The HIT is equal to 1.45 percent of an employee’s wages, deducted from the employee’s wages and matched by the employee’s employer and deposited into the Medicare Part A trust fund.
Initial Enrollment Period
The earliest age a “fully insured” individual can enroll in Medicare Part A (Hospital Insurance) is age 65. If the individual is eligible to enroll in Medicare Part A, the individual is automatically eligible to enroll in the other parts of Medicare; namely, Medicare Part B (Medical Insurance), Medicare Part C (Medicare Advantage) and Medicare Part D (Prescription Drug coverage).
“Fully insured” individuals can enroll in Medicare during their “Initial Enrollment Period” (IEP). The IEP is a seven-month period centered on the month an individual becomes aged 65. The following example illustrates:
Example 1. Patricia becomes 65 on April 16, 2025. Her IEP was the seven- month period starting January 1,2025 and ending July 31, 2025.
It should be noted that individuals who have received Social Security Disability Insurance (SSDI) for 24 months prior to age 65 will be eligible to enroll in Medicare at that time. They should receive their “Welcome to Medicare” kit in their 21st or 22nd month of receiving monthly Social Security disability benefits.
During the IEP, most individuals who are actively employed past their 65th birthday and get health insurance through their employer (for example, federal employees through the Federal Employees Health Benefits Program) can safely delay enrolling in Medicare Part A until the employee retires. Most federal employees take Medicare Part A when they are age 65 because it is free (no monthly premium) . This is because the monthly premiums were prepaid through the HIT -see above). The employee can enroll in Medicare Part A but is not required to.
How Does the General Enrollment Period Work?
Federal employees and retirees who are 65 or older may use the Medicare GEP to enroll in Medicare Part A and Medicare Part B. The GEP is held annually during January, February or March. Medicare coverage starts the month after they sign up, regardless of which month they enroll and which parts of Medicare they choose. The following example illustrates:
Example 2. Robert, age 66, retired from federal service on March 31, 2024 at the age of 64. He is enrolled in the FEHB program. When he became age 65 in May 2025, he did not enroll in Medicare. His IEP started February 1,2025 and ended August 31, 2025. Robert can enroll in Medicare during the current GEP which runs from January 1, 2026 through March 31, 2026. The following table summarizes when Robert’s Medicare Part A and Medicare Part B enrollment becomes effective when he enrolls during the GEP.
There are individuals who enroll in Medicare Part A only during their IEP but decide not to enroll in Medicare Part B. Federal employees enrolled in the FEHB program and who continue to work in federal service past age 65 are advised not to enroll in Medicare Part B while they continue working in federal service. FEHB program-sponsored health insurance is the “primary payer” leaving little or no role for Medicare Part B. Paying a monthly premium for Medicare Part B may not make sense while FEHB program coverage is primary coverage. Once the employee retires from federal service and, assuming the retiring employee is eligible to retain FEHB insurance in retirement, the retired employee is eligible to enroll in Medicare Part B without penalty during a Special Enrollment Period (SEP). The SEP is an eight-month period starting on the effective date of the employee’s retirement from federal service. Once enrolled in both Medicare Part A and Medicare Part B, Medicare becomes the primary payers of a federal retiree while the FEHB program health insurance (the “Medicare supplement”) becomes the secondary payer.
Federal employees are advised to enroll in Medicare when they are first eligible. If they retire from federal service before age 65, they are advised to enroll in Medicare during their IEP. If they retire from federal service after age 65 and they are enrolled in a FEHB program health insurance plan, then they are advised to enroll in Medicare Part A during their IEP and enroll in Medicare Part B during their SEP (an eight-month period starting the first day of the month after the month the employee and continuing until the end of the eighth month) .
The GEP therefore gives federal retirees who do not enroll in Medicare when they are first eligible to enroll in Medicare. However, a late enrollment penalty may apply.
If a Medicare-eligible individual delays enrolling in Medicare Part B and does not have other qualifying coverage, then the individual may face a late enrollment penalty. This penalty adds 10 percent for each full 12-month period. The individual waited to enroll in Medicare Part B. This penalty will apply for the entire time the individual is enrolled in Medicare Part B. The following example illustrates the Medicare Part B penalty:
Example 3. Barbara’s IEP ended on December 31, 2023. She waited until March 2025 during the GEP to enroll in Medicare Part B. Medicare Part B coverage took effect on April 1, 2025. Barbara was therefore not enrolled in Medicare Part B for the 15-month period starting January 1,2024 through March 31, 2025. Barbara’s Medicare Part B premium penalty is equal to 10 percent of the first income tier for the 2024 Medicare Part B first income tier monthly premium (10 percent of $174.74, or $17.47). Barbara will have to pay an additional $17.47 each month for her Medicare Part B premium. Note that Barbara’s penalty is limited to 10 percent. This is because Barbara was not enrolled in Medicare Part B for 15 months. This included one full 12-month period.
Medicare GEP and Medicare Part D
Those federal employees or retirees who enroll in Medicare Part A and for Medicare Part B during the GEP also get a related Medicare Part D SEP to pick up prescription drug coverage. This SEP begins the day the employee or retiree submits their application for Medicare Part A or Medicare Part B and lasts for the first two months of enrollment in Medicare Part A and/or Medicare Part B. This prescription drug coverage begins the first day of the month following the month the employee or retiree enrolls in Medicare Part D.