If Mr. Castillo has stopped paying his Part B premium, what is his status regarding Medicare Advantage plans?

To enroll in a Medicare Advantage (MA) plan, individuals must maintain their eligibility for Medicare Part B. If Mr. Castillo has stopped paying his Part B premium, he will lose his Part B coverage, and thus he would no longer be eligible to enroll in a Medicare Advantage plan.

Before Mr. Castillo can join a Medicare Advantage plan, he needs to reenroll in Part B to regain that essential coverage. This requirement is in place because Medicare Advantage plans are essentially an alternative way to receive Medicare benefits that include both Part A (hospital insurance) and Part B (medical insurance). Without active Part B coverage, he cannot receive the necessary services that MA plans offer.

The relationship between Medicare Part B and Medicare Advantage plans is crucial, as the latter cannot operate independently of the former. Therefore, the correct action for Mr. Castillo to take is to reenroll in Part B before he can proceed with enrolling in a Medicare Advantage plan.