While employment with the Postal Service does not mandate Medicare enrollment, certain employees must enroll in Medicare Part B to retain PSHB coverage after retirement. An annuitant before January 1, 2025, or an active employee aged 64 or older on that date, is exempt from this requirement. However, active employees under 64 as of January 1, 2025, and those retiring after that date and under 64, are generally required to enroll in Medicare Part B upon retirement and Medicare Part A eligibility. Exceptions to this requirement are outlined below.