If a patient has coverage under two insurance plans, which one is the primary plan?

The primary plan is determined by specific coordination of benefits rules, which are designed to establish the order in which multiple insurance plans will pay for a patient's healthcare expenses. The plan that has been in effect for the patient the longest typically serves as the primary payer. This is because longevity indicates that the plan has a stronger established relationship with the patient, making it responsible for paying claims first.

When a patient is covered by two different insurance plans, the primary insurance pays first, and the secondary insurance covers the remaining costs, subject to its own policy limits and rules. This helps to prevent insurance companies from both paying for the same expenses, which can create complications and potential issues with claim payments.

In the context of the other options, while the spouse's plan might be a strong candidate for primary coverage in some situations (for instance, if the patient is often covered by their spouse's employer), it is not a definitive rule. The patient's plan might also be primary, but it is not guaranteed without assessing duration of coverage. The statement that either plan might be primary depending on coverage lacks the specificity needed to determine the primary payer consistently, thus making the length of time each plan has been active the most reliable rule. Therefore, determining the primary plan based on longevity (