When can Mrs. Thomas enroll in Medicare Part B?

Mrs. Thomas can enroll in Medicare Part B anytime while actively working if she meets certain criteria, particularly if she is covered by a group health plan through her employer. This option allows her to delay enrolling in Part B without facing a late enrollment penalty, as long as she has credible health coverage.

It's important to note that the Annual Open Enrollment Period is specific to different aspects of Medicare enrollment, where beneficiaries can make changes to their Medicare Advantage or prescription drug plans, not specifically for enrolling in Part B. The limitation of enrollment to just the month of her birthday or her company's retirement seminar would be overly restrictive and does not reflect the flexibility provided to those who are still employed and covered by a health plan.