A physician who does not accept Medicare assignment for a covered Part B service may charge the beneficiary:

Why A is correct

Nonparticipating (non-assigning) physicians may bill more than the Medicare-approved amount for Part B services. Medicare pays its usual 80% share based on the approved amount, and the beneficiary is responsible for the balance — the 20% coinsurance plus the amount over the approved amount — up to the limiting charge ceiling that caps how much more the physician may charge. Participating (assigning) providers, by contrast, accept the approved amount as payment in full, leaving the beneficiary only the 20% coinsurance.

Why the other options are wrong

• B) The ability to charge more than the approved amount is precisely what distinguishes non-assigning from participating physicians. The key difference is the ability to bill above the Medicare-approved amount.
• C) Medicare still pays its share of the approved amount for non-assigned services; it does not pay nothing. Medicare still pays its usual share based on the approved amount for the service.
• D) That arrangement describes assignment, in which the provider accepts the approved amount; a non-assigning provider may bill above it. A non-assigning provider bills above the approved amount instead of accepting it.

Memory hook

Assignment = accept Medicare's price as the whole price. Non-assignment = bill above it, capped by the limiting charge.