Liz Weston

Dear Liz: You recently answered a question about whether someone 65 or older with employer-provided health insurance needs to sign up for Medicare Part B, which covers doctors’ visits and requires paying premiums. Your answer was correct for an employee of a large employer. If the employer has 20 or more employees on a typical business day, then the group insurance coverage is primary when the employee has both Medicare and group insurance. So the employee does not need to purchase Medicare Part B. However, if the employer has fewer than 20 employees on a typical business day, then Medicare is primary for the employee. In that situation, the employee should buy Medicare Part B. The group health plan will not pay what Medicare should have paid had the employee elected Part B. Your answer needs the appropriate clarification.

Answer: The question was from a spouse who wanted to make sure that the rules covering her husband — the employee — also applied to her, which they do. The employee was told by his employer that he would not need to purchase Medicare Part B until he retired (and even then, there is an eight-month grace period before penalties start to accrue). That applies to spouses covered by the health insurance as well.

But you’re correct that smaller companies have different rules. It’s always a smart idea to seek clarification directly from a company’s human resources department and the health insurer as well as from the Medicare helpline at (800) MEDICARE ([800] 633-4227).