Which of the following healthcare providers is likely to be classified as a non-participating provider?

A primary care physician who does not accept Medicare reimbursements is classified as a non-participating provider because they have chosen not to accept the predetermined fees set by Medicare for services rendered. Non-participating providers can still provide services to Medicare patients, but unlike participating providers, they are not required to accept Medicare's assignment, which means they are not obligated to accept the Medicare-approved amount as full payment. Instead, they may bill patients directly and can charge more than the Medicare fee schedule, although there are limits to how much they can bill.

In contrast, an urgent care nurse typically functions as a staff member under a provider and does not independently bill Medicare. A specialist accepting Medicare assignments intentionally complies with the program's guidelines to receive set reimbursements. An outpatient physical therapist may be either participating or non-participating, depending on their agreements with Medicare, but the question specifically highlights a primary care physician's non-participation status.