State Scope of Practice: The Foundation of APP Authority
- NP scope of practice is governed by the state board of nursing. As of 2024, the American Association of Nurse Practitioners (AANP) reports that 27 states plus Washington, D.C. grant NPs full practice authority (FPA), meaning they can evaluate, diagnose, order tests, prescribe medications (including controlled substances), and manage patients without physician oversight. The remaining 23 states require a collaborative agreement or supervisory relationship with a physician. The specific requirements (chart co-signature, on-site presence, periodic chart review frequency) vary by state. California's AB 890 (effective January 2023) created a new category of FPA-eligible NPs with 4,600 hours of supervised clinical experience.
- PA scope of practice is governed by the state medical board in most states. The 2022 AAPA model state legislation promotes Optimal Team Practice (OTP), eliminating mandatory supervisory agreements in favor of collaborative arrangements. As of 2024, 11 states have adopted OTP for PAs. In states that still require physician supervision, the required physician-to-PA ratio varies (commonly 1 physician per 2 to 4 PAs), and the physician may or may not need to be physically present at the practice site. Some states require the supervising physician to review and co-sign a percentage of PA charts (commonly 10% to 20%) within a specified timeframe (24 to 72 hours).
- CRNA supervision requirements are among the most contentious in healthcare law. CMS requires physician supervision of CRNAs unless the state has opted out of the federal supervision requirement (42 CFR 482.52). As of 2024, 24 states have opted out, allowing CRNAs to practice independently of anesthesiologist or surgeon supervision. In states that have not opted out, a physician (surgeon or anesthesiologist) must be immediately available during CRNA-administered anesthesia. Immediately available means physically present in the facility, not merely reachable by phone.
- Surgical practices operating across multiple state lines (e.g., telehealth pre-op evaluations, multi-state practice groups) must comply with the supervision laws of the state where the patient is located at the time of service, not the state where the supervising physician is located. This is a frequent compliance gap in multi-site surgical organizations. Each APP's collaborative agreement or supervisory documentation must reference the laws of the state where the APP is practicing.
CMS Billing Rules: Independent vs. Incident-To
- NPs and PAs can bill Medicare independently under their own NPI at 85% of the physician fee schedule. No supervision is required for independent billing. The APP performs, documents, and bills the service under their own name. This approach is straightforward but results in a 15% payment reduction. Independent billing is available in all practice settings (office, ASC, hospital outpatient, facility).
- Incident-to billing reimburses APP services at 100% of the physician fee schedule when specific conditions are met. Per CMS Medicare Benefit Policy Manual Chapter 15, Section 60, the following requirements must all be satisfied: the physician must have performed the initial service and established the plan of care for the patient's condition; the APP service must be an integral part of the physician's ongoing treatment; the physician must provide direct supervision (present in the office suite, not necessarily in the same room) at the time the APP furnishes the service; and the service must be billed under the physician's NPI. Incident-to billing is only available in the physician office setting, not in hospital outpatient departments, ASCs, or inpatient settings.
- CMS auditors specifically scrutinize incident-to arrangements. The OIG Work Plan has included APP supervision compliance as a priority area since 2018. Common audit findings include: incident-to billing when the supervising physician was not in the office suite (e.g., at a different clinic location, working remotely); incident-to billing for new patient visits or new problems (which require the physician to establish the plan of care first); and missing or incomplete collaborative agreements in states that require them. Overpayment recoupment is the standard remedy: CMS recoups the 15% difference between the 100% incident-to payment and the 85% independent billing rate, plus interest.
- Shared/split visits (where both the physician and APP see the same patient on the same day) follow separate rules under the CY2022 Medicare Physician Fee Schedule Final Rule. For non-facility settings, the billing provider is the one who performs the substantive portion of the visit. CMS defines the substantive portion as more than half of the total time or the practitioner who performs the history, exam, or medical decision-making component that determines the E/M level. Practices must document which provider performed the substantive portion and ensure the billing provider's signature and attestation are in the medical record.
Facility-Specific Supervision Standards
- Ambulatory Surgery Centers (ASCs) must comply with CMS Conditions for Coverage (42 CFR 416) regarding APP involvement in surgical cases. PAs may serve as first assistants during surgery, but the operating surgeon must be present throughout the procedure. NPs may perform pre-operative assessments, post-anesthesia evaluations, and discharge assessments at ASCs if authorized by state law and the facility's privileging process. Each APP must have a credentialing file and specific privilege delineation on record at the ASC.
- Office-based surgery (OBS) settings follow state-specific rules. In states with OBS regulations (California, Florida, New York, Texas, and approximately 20 others), the regulations specify which providers may administer sedation, who must be present during the procedure, and what post-procedure monitoring is required. In California, the Medical Board of California OBS guidelines require that a licensed physician be on-site whenever deep sedation or general anesthesia is administered, regardless of whether a CRNA is providing the anesthesia.
- Hospital outpatient departments (HOPDs) follow hospital medical staff bylaws for APP supervision. CMS Conditions of Participation (42 CFR 482.12) require the medical staff to establish policies on APP privileging and supervision. In the HOPD setting, incident-to billing rules do not apply. APP services are billed under the hospital's outpatient prospective payment system (OPPS), and the professional component is billed at 85% of the physician fee schedule under the APP's own NPI, regardless of physician presence.
- Telehealth supervision has evolved since CMS expanded telehealth flexibilities during the COVID-19 public health emergency. For telehealth visits performed by APPs, the same state scope-of-practice rules apply. If the state requires a collaborative agreement, that agreement must cover telehealth services. For incident-to telehealth billing (in the office setting where the APP is physically present), the supervising physician must be present in the office suite during the telehealth encounter, even though the patient is remote. CMS has not adopted virtual supervision (physician available by video) as meeting the direct supervision standard for incident-to billing as of 2024.
Building a Compliant APP Supervision Program
- Maintain a current supervision matrix that maps each APP to their supervising physician(s), the applicable state law requirements, the collaborative agreement or practice agreement terms, the chart review frequency and documentation requirements, and the billing arrangement (independent vs. incident-to). Update this matrix whenever an APP is hired, a supervising physician leaves, or state law changes. This document is the first thing an auditor will request.
- Implement prospective scheduling controls. If your practice uses incident-to billing, the scheduling system should verify that the supervising physician is scheduled to be in the office on the same day as the APP. If the physician calls in sick or is called away to the hospital, all APP services that day must be billed independently (85%) rather than incident-to (100%). Retroactive rebilling from incident-to to independent billing is permissible but operationally burdensome and invites audit attention.
- Conduct quarterly internal audits of 20 to 30 APP encounters per quarter, stratified by billing type (incident-to vs. independent). For incident-to claims, verify: the physician was physically in the office suite (check physician schedule, EHR login records, badge access logs); the physician established the plan of care at a prior visit; the APP's note references the established plan; and the claim was submitted under the physician's NPI. For shared/split visits, verify substantive-portion documentation. Document audit results and corrective actions in writing.
- Train APPs and billing staff annually on supervision and billing compliance. Common knowledge gaps include: APPs not knowing which billing arrangement applies to their services; front-desk staff scheduling APP visits on physician-off days without adjusting the billing type; and physicians not understanding their obligation to be physically present (not just available by phone) for incident-to supervision. The Compliance Program Guidance for Individual and Small Group Physician Practices (OIG, 2000) recommends documented annual training with attendance records and content logs.