Final answer:
The primary insurance plan for someone eligible for both a company health plan and Medicare depends on their employment status and the employer's size, with the employer's plan being primary if the company has 20 or more employees, and Medicare being primary if there are fewer than 20 employees.
Step-by-step explanation:
If Sam is eligible for both his company's health plan and Medicare, the primary insurance plan depends on his employment status and the size of the employer. However, without specific details about Sam's situation, such as his employer's size and if he is actively working, a definitive answer cannot be provided. Generally, for those who are actively working at a company with 20 or more employees, the employer's health plan is usually primary. Conversely, if the company has fewer than 20 employees, Medicare is often considered the primary plan. Coordination of benefits may be necessary to ensure that the benefits from both plans are utilized appropriately.