In most states, a supervising physician does not have to be on site while a physician assistant or nurse practitioner treats patients — state law generally allows supervision by phone or video for routine care. The catch is Medicare. Federal billing rules impose their own presence requirement for certain services, and those rules apply no matter how permissive your state is. So the honest answer to whether a supervising physician has to be on site is: it depends on what your state requires, what the PA or NP is doing, and, above all, how the visit is being billed.
What State Law Actually Requires
Every state sets its own supervision rules, and they generally fall into a few categories. A minority of states still require direct, on-site supervision for certain services, meaning the physician must be physically in the building. This model is becoming less common, though it still shows up in specific practice settings or for particular high-risk procedures even in otherwise flexible states.
The more widely used framework is general or remote supervision. The physician does not need to be in the facility but must remain reachable by phone or video for consultation. Oversight responsibility stays with the physician, chart reviews happen on a set schedule, and the PA or NP handles day-to-day patient care within the scope defined by their agreement.
For nurse practitioners, the ground has shifted substantially. Twenty-seven states plus the District of Columbia and two U.S. territories grant NPs full practice authority, meaning they can evaluate patients, diagnose, and prescribe with no physician oversight at all. Another group of states allow NPs to work under a collaborative agreement that stops short of full independence. The most restrictive states still require direct physician supervision.
Physician assistants operate under tighter rules everywhere, though the trend is toward flexibility. At least eight states have dropped the requirement that PAs maintain a formal supervisory agreement, moving instead to a collaborative model. No state has given PAs the fully independent authority some NPs enjoy.
The bottom line at the state level: for most routine PA and NP care, the supervising physician does not have to be in the building. Being reachable is enough. The states and services where on-site presence is still mandated are the exception, and they are shrinking.
When Medicare Requires the Physician to Be Present
State law only tells half the story. Even where general supervision is legal, Medicare has a separate standard that kicks in based on how the visit is billed. This is where practices get into real trouble, because getting it wrong is not a licensing footnote — it is federal fraud exposure.
When a practice bills Medicare for services “incident to” a physician’s professional services, the physician (or another qualifying practitioner) must provide direct supervision.1CMS. Incident To Services and Supplies Incident-to billing is attractive because it reimburses at the physician’s full rate rather than the lower rate paid when the NP or PA bills independently. The price of that higher rate is that the physician must be directly supervising the encounter.
Direct supervision under Medicare means the physician must be immediately available to assist if needed. Historically that meant being somewhere in the same office suite. Starting January 1, 2026, CMS permanently adopted a revised definition that allows the physician to satisfy this requirement through real-time audio and video telecommunications, not audio-only, for most incident-to services.2eCFR. Title 42 CFR 410.26 – Services and Supplies Incident to a Physicians Professional Services The change makes permanent a flexibility that started during the COVID-19 public health emergency and had been extended on a temporary basis through the end of 2025.3CMS. Telehealth FAQ
The virtual option does not apply to every service. Procedures with a 010 or 090 global surgery indicator still require the physician’s physical presence. And certain incident-to services only require general supervision, meaning the physician does not need to be present or virtually available at the time of service; this includes designated care management services and behavioral health services provided by auxiliary personnel.2eCFR. Title 42 CFR 410.26 – Services and Supplies Incident to a Physicians Professional Services
So the practical rule for private-office billing: if you want the physician-rate reimbursement that comes with incident-to billing, someone qualifying as the supervisor must be in the suite or on live video during the visit. For surgical procedures with a global period, they need to be physically there.
Split and Shared Visits
A related Medicare rule applies to split or shared visits, where a physician and an NP or PA in the same group both see the same patient during a facility-based encounter. The practitioner who performs the substantive portion of the visit, defined as more than half the total time or a substantive part of the medical decision-making, is the one who bills.4CMS. Updates for Split or Shared Evaluation and Management Visits Split or shared billing only applies in facility settings like hospitals and skilled nursing facilities, not in private offices. The rule dictates when a physician must actually be on site to bill at the physician rate for a shared patient encounter.
Other Factors That Push Oversight Higher
Even in a state that broadly permits off-site supervision, the practical level of oversight required for a specific PA or NP can vary.
The complexity and risk of the services matter most. A PA managing routine follow-up visits for stable chronic conditions will operate under lighter oversight than one assisting with invasive procedures. Setting matters too. Hospitals frequently impose their own credentialing and supervision requirements that go beyond what state law demands, while small outpatient clinics tend to default to the state minimum.
Experience is a significant factor. Many states require more intensive physician oversight for newly practicing PAs, including more frequent chart reviews and closer availability for consultation. After a set period, often one to two years, the supervising physician gains discretion to scale back review frequency based on demonstrated competence. A PA with ten years of specialty experience needs different oversight than someone fresh out of training.
When the Named Supervisor Is Out
Practices get caught off guard when the designated supervising physician is unexpectedly unavailable, whether from illness, vacation, or being out of the office longer than planned. Most states that require a supervisory relationship also require the physician to designate at least one alternate or substitute physician who can step in during absences.
The substitute generally must meet the same qualifications and provide the same level of oversight as the primary supervisor. The arrangement cannot be used to sidestep limits on how many PAs a single physician can supervise. Some states require the alternate’s name to be filed with the medical board in advance; others allow informal substitution as long as it is documented. The underlying principle is the same everywhere: a PA should never be practicing without an identified supervising physician available, even temporarily.
What Happens if Supervision Falls Short
The consequences of missing supervision requirements come from three different directions, and each one operates independently.
Board Discipline
State medical boards can investigate and sanction both the supervising physician and the PA or NP when supervision falls short. Available penalties include fines, license suspension, license revocation, probation, and public reprimand.5FSMB. About Physician Discipline Investigations can be triggered by patient complaints, malpractice reports, or random audits. Boards view a physician who signs supervisory agreements but provides no meaningful oversight as failing a core regulatory obligation, not committing a paperwork slip.
Malpractice and Vicarious Liability
If a patient is harmed while being treated by a PA or NP, the supervising physician can be pulled into the malpractice suit even if they never personally saw the patient. Vicarious liability holds the supervising physician responsible for the clinical decisions of someone they were legally obligated to oversee. The less oversight the physician actually provided, the stronger the plaintiff’s argument that negligent supervision contributed to the harm. The supervisory agreement cuts both ways here: it defines the standard the physician promised to maintain, and any gap between what it says and what actually happened becomes evidence.
Federal False Claims Act Exposure
The most financially damaging consequence applies specifically to billing. When a practice bills Medicare or Medicaid for services that lacked the required level of physician supervision, every one of those claims can be treated as a false claim under federal law. The False Claims Act imposes liability on anyone who knowingly submits a false or fraudulent claim for government payment.6Office of the Law Revision Counsel. 31 USC 3729 – False Claims CMS has specifically identified billing for services performed by an improperly supervised employee as an example of a claim that could violate the Act.7CMS. Medicare Fraud and Abuse – Prevent, Detect, Report
The penalties are designed to hurt. Civil liability includes three times the government’s actual damages plus a per-claim penalty that, after inflation adjustments, currently exceeds $14,000 at the low end and can reach nearly $29,000 per false claim.6Office of the Law Revision Counsel. 31 USC 3729 – False Claims For a busy practice that has been billing incident-to services without proper supervision for months or years, the arithmetic turns catastrophic quickly; each patient visit is a separate claim. Criminal penalties, including imprisonment, can also apply when false claims are submitted knowingly. Practices found non-compliant typically lose their billing privileges with Medicare and commercial insurers, which usually ends the practice’s financial viability.
That last point is why the on-site question can’t be answered by looking only at state law. State rules tell you what is legally required to practice. Medicare tells you what is required to bill the way most practices actually bill. If those two answers differ, the billing answer is the one that determines whether the physician needs to be there.