Incident-to billing allows physician practices to bill APP-provided services under the physician's NPI — collecting 100% of the Medicare physician fee schedule instead of the 85% paid when an NP or PA bills independently. It's one of the most significant revenue optimization tools in primary care and multi-provider practices. It's also one of the most frequently misused — and a top OIG audit target every year.
What Is Incident-to Billing?
Incident-to billing is a Medicare provision that allows services provided by a non-physician practitioner (NPP) — nurse practitioner, physician assistant, clinical nurse specialist, or other qualified auxiliary staff — to be billed under the supervising physician's NPI as if the physician personally provided the service. When billed correctly, Medicare reimburses at 100% of the physician fee schedule.
When an NPP bills independently under their own NPI, Medicare reimburses at 85% of the physician fee schedule. For a busy NP seeing 20 patients per day, the 15% difference across a full year can exceed $60,000–$100,000 in revenue per provider.
The 5 Requirements for Incident-to Billing
All 5 conditions must be met simultaneously. Missing any single one makes incident-to billing non-compliant — and billing under the physician NPI when requirements are not met is a False Claims Act violation.
Established patient with an established plan of care: The physician must have personally seen the patient, established the diagnosis, and initiated the treatment plan for the condition being addressed. Incident-to does NOT apply to new problems — even in established patients.
The NPP must be following the physician's established plan: The visit must be a follow-up to an ongoing treatment plan established by the physician. If the patient presents with a new problem that day — even if they're an established patient — incident-to billing can't be used for that new problem.
The physician must be present in the office suite: The supervising physician must be physically present in the same office suite (not the same exam room, but the same office) during the NPP's visit. The physician doesn't need to see the patient, but must be immediately available to provide assistance if needed. A physician who is in surgery across the street, at lunch, or working from home can't supervise an incident-to visit.
Direct supervision: The supervision requirement is "direct" — meaning the physician is present in the office suite, immediately available. General supervision (available by phone) is not sufficient for incident-to billing of E/M services.
The NPP must be an employee or contracted staff of the physician or the practice: The NPP must be an employee, leased employee, or independent contractor of the billing physician's practice — not of a separate entity.
The most commonly violated requirement: Billing incident-to when the patient presents with a new problem. An established patient with hypertension who presents for a routine BP follow-up (established plan) may be seen incident-to. If that same patient mentions new knee pain that day and the NPP evaluates it — that new problem can't be billed incident-to, even if the hypertension follow-up component could be.
New Patients: Never Incident-to
New patients — defined as patients who have not received any professional service from the physician or another physician in the same group and specialty within the past 3 years — must always be seen by the physician first before incident-to billing can apply to subsequent visits. The physician must personally establish the patient, perform the initial evaluation, and document the treatment plan.
Practical implication: If an NP in your practice sees a new patient for an initial visit, that visit must be billed under the NP's NPI at 85%. The physician can't bill incident-to for an initial encounter they did not personally perform, even if they review the note afterward.
Incident-to in Different Settings
Setting
Incident-to Allowed?
Notes
Physician office (own practice)
Yes
All 5 requirements must be met
Hospital outpatient department
No
Must bill under NPP's NPI or use split/shared rules
Hospital inpatient
No
Must bill under NPP's NPI or use split/shared rules
Independent clinic (not physician-owned)
No
NPP must bill independently
Federally Qualified Health Center (FQHC)
No
FQHC has its own billing methodology
Rural Health Clinic (RHC)
No
RHC billing methodology applies
Supervision Levels: Direct vs. General
CMS defines three levels of supervision for Medicare purposes:
General supervision: The procedure is furnished under the physician's overall direction but the physician's presence is not required. Applies to many diagnostic tests ordered by physicians.
Direct supervision: The physician must be present in the office suite and immediately available. Required for incident-to E/M services.
Personal supervision: The physician must be in the room during the entire procedure. Required for specific high-risk procedures.
Incident-to E/M services require direct supervision. A physician who is at a different physical location — even if reachable by phone — doesn't satisfy the direct supervision requirement.
State Law May Be More Restrictive
Medicare incident-to rules set the floor, not the ceiling. State scope of practice laws and state Medicaid programs may impose additional restrictions on what NPPs can do under physician supervision — or may require physician co-signature on NPP notes, alter supervision requirements, or restrict certain services entirely. Always verify both Medicare incident-to rules and applicable state regulations before implementing incident-to billing protocols.
Top Incident-to Audit Triggers
1
New problems billed incident-to in established patients
The most common audit finding. NPP evaluates a new complaint and it's billed under physician NPI. Prevention: require NPPs to flag new problems in the EHR and route billing to NPP NPI for that problem — or route to physician for same-day evaluation.
2
Physician not present in office during NPP visit
Physician is out of the office, on vacation, or in a different location. Incident-to billed anyway. Prevention: EHR or scheduling system should require supervising physician log-in confirmation before incident-to claims are generated.
3
Incident-to billed for hospital outpatient visits
Applying office-based incident-to rules to HOPD settings where incident-to doesn't apply. Prevention: separate billing protocols for office vs. facility settings — these are governed by completely different rules.
4
No documented physician treatment plan for the billed condition
NPP sees patient for a condition the physician has never documented evaluating or treating. Prevention: pull chart before NPP visit to confirm physician-established plan of care exists for each condition being addressed.
5
NPP contracted through a different entity
NPP staffed by a temp agency or separate management company — not an employee of the practice. Prevention: review NPP employment contracts before implementing incident-to billing for their services.
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RCMAXIS conducts incident-to billing audits for multi-provider practices — identifying supervision documentation gaps, new problem misclassifications, and setting-based billing errors before they trigger a payer audit.