Medical services are usually billed by the individual who performs the service. However, Medicare has two exceptions — “incident to” and “shared services.” These two rules essentially allow physicians to bill for care provided by clinicians and staff who work with them as if the physicians had done it themselves. They're similar rules, but with key differences.

Incident-to services are performed in physician offices or patients' homes, while shared services are performed in facilities such as hospitals or nursing homes. Incident-to services can be performed by either non-physician clinicians (NPCs) or clinical staff as part of the billing physician's professional services, while shared services must be performed by two clinicians (physicians or NPCs) who each could have billed the service on their own. (See “Incident-to vs. shared services comparison.”)

In either case, though, if the physician is billing, Medicare pays the full physician fee schedule rate, while services billed by NPCs are paid at 85% of that. Some private insurers also allow incident-to billing and shared services billing under rules similar to Medicare's, but this varies by payer.

Shared services rules have changed recently, as CPT has published new definitions (which Medicare has largely adopted, for now). The requirements for incident-to billing haven't changed, but they can be confusing, and because family physicians tend to use incident-to billing more often, a refresher is useful. This article provides that refresher on incident-to billing, as well as an explanation of the changes to shared services billing, and has a set of questions and answers with specific scenarios to help physicians understand when and how to use each of them.