When does coordination of benefits (COB) begin for individuals eligible for Medicare Part A?

Coordination of benefits (COB) refers to the process of determining which of multiple insurance policies will pay first when a person is covered by more than one plan. For individuals eligible for Medicare Part A, COB begins when they become eligible for Medicare. This eligibility typically occurs when individuals reach 65 years of age or if they qualify due to a disability.

When a person becomes eligible for Medicare Part A, they also gain access to the benefits that coordinate with other insurance plans. This is crucial for ensuring that claims are processed correctly and that the beneficiary receives the maximum benefits from both Medicare and any additional insurance they may have.

The other options do not accurately represent when COB begins. For instance, while reaching retirement age may correlate with Medicare eligibility, it does not pinpoint the actual start of COB, which is directly linked to the eligibility for Medicare Part A. Similarly, applying for Medicare does not automatically trigger COB; eligibility must be established first. The enrollment period is also irrelevant to the timing of when COB begins, as it focuses on the window to enroll rather than the actual eligibility date.