If a retired patient with Medicare also has coverage under a working spouse's plan, which plan is considered primary?

When a patient has Medicare and also coverage from a spouse's employer-sponsored plan, the spouse's plan typically serves as the primary insurance. This is due to the coordination of benefits rules established by Medicare.

Medicare generally functions as secondary insurance when a beneficiary has access to an employer-sponsored plan, particularly if that plan is provided by the employer of a spouse, as long as the employer has 20 or more employees. This rule is designed to ensure that the primary insurance (the spouse's plan) handles the bulk of the medical expenses first, which can then reduce the financial burden on Medicare and allow it to cover the remaining eligible costs.

Understanding coordination of benefits is crucial in navigating billing processes effectively. In this scenario, the spouse's plan being the primary insurance means that it pays first, and Medicare may cover any remaining costs, but only for services that are covered under its guidelines. This helps maximize benefits available to the patient, ensuring they receive comprehensive care without unnecessary out-of-pocket expenses.