This past August, WebPT hosted an open forum-style webinar during which we took all of your hardest-hitting, most mission-critical billing questions—and answered them to the best of our ability. One of the most common questions we received had to do with incident-to billing—and it’s easy to see why. After all, you can’t just slap any old NPI number on a claim—particularly when you’re billing Medicare—and expect to get paid. However, in some cases, billing incident to a physician is the best way to receive reimbursement for therapy services. With that in mind, we decided to put together this quick guide to incident-to billing:

What is incident-to billing?

Simply put, incident-to billing gives PTs an avenue for providing services to Medicare beneficiaries—even if they are not credentialed with Medicare or do not have an NPI. Here’s a general rundown on those guidelines (as adapted from this Physician’s Practice article):

  • The PT must render the service in a non-institutional setting, which the Centers for Medicare and Medicaid Services (CMS) describes as “all settings other than a hospital or skilled nursing facility.”
  • A Medicare-credentialed physician or NPP must evaluate the patient and establish the plan of care. A non-credentialed provider cannot render incident-to services during the initial visit or anytime there is a change to the plan of care (e.g., during a reevaluation or treatment change).
  • Once the Medicare-credentialed physician or NPP has established a plan of care for the patient, the PT may render services for subsequent visits. These services must occur under direct supervision of a qualified provider. 
  • Per Medicare, direct supervision does not imply that the qualified provider is in the same room, but simply means that he or she is on site and immediately available to assist the rendering provider.
  • If the rendering provider performs services offsite (e.g., in the patient’s home or in a different facility), he or she must perform the services under the direct, onsite supervision of a qualified provider. Otherwise, those services cannot be billed incident to.
  • The supervising provider does not have to be the physician or NPP who established the plan of care or performed the initial evaluation. Any qualified provider may supervise.
  • The provider under whom the services are billed must be an active participant in the patient’s course of care. Typically, a state’s practice act will give additional specifications for this requirement.
  • Both providers must work for the same group entity that bills the service.
  • The PT may only bill incident to another provider for services typically rendered in the office setting that are part of the normal course of treatment for the condition.

Note: While this information pertains specifically to Medicare guidelines, other payers—such as Medicaid, workers compensation carriers, and commercial insurances—may or may not allow incident-to billing. Contact individual payers directly to confirm their policies.

What are some pitfalls of incident-to billing?

Techs/aides cannot bill incident to the therapist.

During the aforementioned webinar, John Wallace, founder of BMS Practice Solutions, noted that “a fraudulent example of ‘incident to’ billing would be a physical therapy tech performing a service and billing under the PT’s number.” That’s because Medicare will not reimburse for any services rendered by a tech or aide, so attempting to receive payment for these services is a major no-no.

PTs cannot bill incident to other PTs.

According to Wallace, “Medicare does not allow incident-to billing of one therapist under another in the private practice setting.” For private practice PTs, each therapist must be individually credentialed with Medicare. However, Wallace goes on to explain that this rule doesn’t apply to facility-based therapists (e.g., PTs in ORFs, CORFs, or outpatient hospitals) as these providers bill under the facility as opposed to an individual NPI. Additionally, in some cases, PTs in medically underserved or rural areas can take advantage of the arrangement previously referred to as “locum tenens.”

Therapist assistants cannot bill incident to a physician’s services.

While therapist assistants (PTAs, OTAs, and SLPAs) can bill for services incident to a qualified, credentialed therapist, they cannot bill incident to a physician. That’s because assistants must provide services under the direct supervision of a licensed therapist. Furthermore, assistants do not meet the qualifications of a therapist, which is the only type of therapy provider that can bill incident to a physician.

Assistants may only bill incident to providers within the same discipline.

Per CMS, PTs must supervise PTAs, OTs must supervise OTAs, and SLPs must supervise SLPAs. In other words, therapist assistants may only bill incident to therapists within the same discipline.


So there you have it: the essentials of incident-to billing in outpatient rehab therapy. Still feeling stumped? Then be sure to attend our upcoming Medicare Open Forum. Our hosts will provide more insight into all sorts of Medicare compliance issues—including those related to billing—as they tackle your toughest questions live.