Incident-To Billing for Nurse Practitioners: Medicare Rules and Common Mistakes

If your practice employs nurse practitioners, you've probably had this conversation at some point: can we bill this visit incident-to, or does it need to go under the NP's own NPI? It sounds like a small distinction, but it's worth 15 percentage points of reimbursement on every qualifying visit, and getting it wrong in the wrong direction is exactly the kind of thing that shows up in an OIG audit letter a year later.

Incident-to billing has been part of Medicare Part B since long before nurse practitioners became as central to outpatient care as they are today. The rule itself hasn't changed much in decades, but a genuinely significant piece of it, how direct supervision is defined, changed permanently as of January 1, 2026. On top of that, if you're practicing in California, AB 890's rollout of independent NP practice authority is creating real confusion about whether incident-to billing even applies anymore to NPs who no longer need a supervising physician under state law.

This article walks through what Medicare actually requires, what changed this year, where practices consistently get it wrong, and what the California independent practice shift means for how you bill.

What Incident-To Billing Actually Means

Incident-to is a Medicare Part B billing provision, not a code or a modifier. It allows services furnished by a nurse practitioner, physician assistant, or clinical nurse specialist to be billed under the supervising physician's NPI, as though the physician performed the service personally.

The financial difference is the whole reason this matters. A service billed under an NP's own NPI is reimbursed at 85 percent of the Medicare Physician Fee Schedule, under 42 CFR 414.56(c). The same service billed correctly as incident-to is reimbursed at 100 percent, under the physician's NPI. On high volume, that gap adds up fast.

But incident-to isn't a shortcut. It's a coverage provision with a specific set of conditions attached, and Medicare treats every one of them as a requirement, not a suggestion.

The Core Requirements Medicare Looks For

For a visit to qualify as incident-to, it generally needs to meet all of the following:

1. The patient is established, not new to the practice.
2. The problem being addressed is one the physician has already evaluated and initiated a plan of care for, not a new problem the NP is addressing independently for the first time.
3. The physician initiated the plan of care. The NP can manage and adjust it, but the physician has to have started it.
4. The NP is employed by, or properly leased to, the same physician or group billing the service.
5. The service is furnished in a noninstitutional setting, generally the physician's office or clinic, not a hospital.
6. Direct supervision is in place during the visit, meeting Medicare's specific definition of that term.

Miss any one of these, and the visit isn't incident-to eligible, regardless of how good the clinical care was. This is a billing determination, not a clinical one.

What Changed: Direct Supervision in 2026

This is the part of the rule that's actually moved this year, and it's worth understanding clearly.

Historically, direct supervision meant the supervising physician had to be physically present in the office suite and immediately available throughout the visit, not necessarily in the same exam room, but somewhere in the building and reachable in person. Being available by phone never satisfied this requirement.

During the COVID-19 public health emergency, CMS temporarily allowed direct supervision to be met virtually, through real-time, two-way audio-video technology. That flexibility was extended repeatedly, year by year, and under the CY 2026 Medicare Physician Fee Schedule Final Rule, CMS made it permanent. The Consolidated Appropriations Act of 2026, signed February 3, 2026, further extended related telehealth provisions.

What direct supervision means as of January 1, 2026

1. Direct supervision can now be met with the supervising physician available through live, interactive audio and video technology, rather than requiring physical presence in the office.
2. Audio-only availability does not qualify. The connection has to include real-time video as well as audio.
3. The physician's virtual presence has to be active and available throughout the visit, not just reachable if paged.

The exception

Services with a global surgery indicator of 010 or 090, meaning minor and major procedures with bundled postoperative follow-up periods, still require the physician to be physically present on-site. Virtual supervision doesn't satisfy the requirement for these.

This is a meaningful operational change, particularly for practices running a hybrid model where the physician splits time between locations. But it doesn't relax anything else about incident-to. The established patient requirement, the existing problem requirement, and the physician-initiated plan of care requirement are all exactly as strict as they were before.

Where Incident-To Billing Doesn't Apply

A few settings and scenarios are flatly outside incident-to's scope, and this is where a lot of avoidable denials come from.

1. Hospital settings. Incident-to billing does not apply in the hospital, whether inpatient, outpatient, observation, or the emergency department. Facility-based encounters involving both a physician and an NP fall under split/shared billing rules instead, which work differently.
2. New patients. If the patient hasn't been seen and evaluated by the practice before, the visit doesn't qualify for incident-to, regardless of supervision arrangements.
3. New problems the NP is addressing independently. If the NP identifies and starts managing a condition the physician hasn't already evaluated and built a plan of care around, that visit falls outside incident-to.
4. Diagnostic testing. Tests like certain lab and radiology services have their own Medicare benefit category and supervision rules under 42 CFR 410.32, which is separate from, and different from, the incident-to supervision standard.

Incident-To vs. Split/Shared Billing

These two provisions get confused constantly, and they're not interchangeable.

Incident-to billing

Applies in the office or clinic setting. It's used when an NP sees an established patient for an existing problem under a physician-initiated plan of care, with direct supervision in place. The visit is billed entirely under the physician's NPI at 100 percent.

Split/shared billing

Applies in facility settings, inpatient, outpatient, observation, or the emergency department, when a physician and an NP jointly participate in the same encounter. Whichever practitioner performs the substantive portion of the visit, generally defined as more than half of the total time or the substantive part of the medical decision making, bills for it, with modifier FS appended to the claim. Critical care visits under this framework are evaluated on time alone.

Setting is the deciding factor. Office visits run through incident-to logic. Facility visits run through split/shared logic. Mixing the two up, most often by trying to apply incident-to rules inside a hospital, is one of the recurring themes the OIG has flagged in audit work related to NP and PA billing.

What California Practices Need to Know About AB 890

California is in the middle of a real shift in how independently NPs can practice, and it's creating genuine confusion about what that means for billing.

Assembly Bill 890 created two new practice categories for California NPs. A 103 NP, who has completed a transition-to-practice period of at least three full-time-equivalent years or 4,600 hours, can practice without standardized procedures, but only within a group setting where a physician also practices. A 104 NP, a designation that became available for the first time on January 1, 2026, can practice fully independently outside of a group setting altogether, after an additional period of practice as a 103 NP.

This is a genuine expansion of scope-of-practice authority under California law. It removes the requirement for standardized procedures and physician oversight for qualifying NPs. What it doesn't do is change Medicare's federal incident-to billing rules.

The distinction that matters for billing

AB 890 governs whether a California NP needs a supervising physician to practice legally under state law. Incident-to billing is a federal Medicare coverage and payment rule with its own independent supervision, plan-of-care, and established-patient requirements. A 103 or 104 NP who is practicing with full state-law independence is not automatically eligible for incident-to billing just because a physician happens to be in the building. If the NP initiated the plan of care herself, for a new problem, without physician involvement, that visit doesn't meet Medicare's incident-to criteria, regardless of what California law allows.

In practice, this means California practices need to make a deliberate choice for their independently practicing NPs: structure specific visits to genuinely meet Medicare's incident-to conditions when that's clinically appropriate and billing at 100 percent is the goal, or bill under the NP's own NPI at 85 percent when the NP is functioning with true independence. Trying to have both at once, independence under AB 890 and incident-to billing at 100 percent for the same encounter, is where compliance risk lives.

Common Mistakes That Trigger Denials or Audits

1. Billing new patient visits as incident-to. This is one of the most frequent errors, and one of the easiest for a payer to catch.
2. Billing incident-to in a hospital-based setting. Facility encounters need split/shared logic, not incident-to.
3. Treating "physician down the hall" as automatic incident-to eligibility, without confirming the patient is established and the problem was physician-initiated.
4. Using audio-only phone availability as direct supervision. The 2026 rule requires real-time audio and video, not a phone call.
5. Forgetting the global surgery indicator exception. Virtual supervision doesn't satisfy the requirement for services with a 010 or 090 indicator; physical presence is still required there.
6. Assuming California's independent practice authority extends to federal billing rules. State scope-of-practice expansion and Medicare's incident-to criteria are governed separately.
7. Billing incident-to when the NP is not employed by, or properly leased to, the billing physician or group. This employment relationship is a hard requirement, not a formality.

Actionable Tips for Getting It Right

1. Build a simple pre-visit checklist your front desk or scheduling team can use to flag new patients and new problems before the visit even happens, so the billing decision is made correctly from the start rather than reconstructed afterward.
2. Confirm the plan of care documentation names the physician as the one who initiated it, even when the NP is managing day-to-day adjustments.
3. If your practice uses virtual direct supervision, document the technology used and confirm it's live, two-way audio and video, not a phone line, and keep a record that the physician was actually available and connected during the visit.
4. Flag the global surgery indicator exception in your EHR or billing system so staff don't default to virtual supervision for procedures that still require physical presence.
5. For California practices with 103 or 104 NPs, decide deliberately, encounter by encounter, whether the visit is being billed incident-to or under the NP's own NPI, and make sure your documentation supports whichever one you choose.

Documentation That Actually Holds Up

The chart needs to answer the same questions an auditor will ask.

1. Was this patient established with the practice before this visit?
2. Is the condition being addressed one the physician already evaluated and built a plan of care around?
3. Does the record show the physician initiated that plan, not just that the physician is affiliated with the practice?
4. Is there evidence of direct supervision consistent with Medicare's current definition, physical or virtual, for this specific date of service?
5. Is the NP's employment or leasing relationship with the billing physician or group documented and current?

If any of these can't be answered clearly from the chart alone, that's the visit worth reviewing before the claim goes out, not after a denial comes back.

Expert Recommendations

Practices that handle incident-to billing well tend to treat it as a workflow decision made at the front end, not a coding decision made after the visit is already documented. By the time a biller is looking at the note trying to decide which NPI to use, the information needed to make that call correctly should already be sitting in the chart.

For groups navigating the 2026 supervision change, it's worth running a short internal audit of how virtual supervision is actually being documented right now. A lot of practices adopted the flexibility quickly without updating their templates to capture the specific elements, live video, physician availability, and duration, that would hold up under review.

California practices adding 103 or 104 NPs to their staffing model should treat the incident-to decision as a deliberate business choice tied to each NP's actual practice pattern, not a default setting left over from before AB 890 took effect. An NP functioning with genuine independence under state law, seeing patients and initiating their own plans of care, isn't a billing problem. Billing that same independent care as incident-to is.

Frequently Asked Questions

What is incident-to billing under Medicare?

Incident-to billing is a Medicare Part B provision that allows services furnished by a nurse practitioner, physician assistant, or clinical nurse specialist to be billed under a supervising physician's NPI at 100 percent of the Medicare Physician Fee Schedule, provided specific conditions are met.

What's the reimbursement difference between incident-to and billing under an NP's own NPI?

Services billed under an NP's own NPI are reimbursed at 85 percent of the Medicare Physician Fee Schedule under 42 CFR 414.56(c). Correctly billed incident-to services are reimbursed at 100 percent under the physician's NPI.

Does incident-to billing apply to new patients?

No. Incident-to billing requires an established patient. New patient visits do not qualify, regardless of supervision arrangements.

Can incident-to billing be used in a hospital?

No. Incident-to billing applies to noninstitutional settings, generally the office or clinic. Facility-based encounters, including inpatient, outpatient, observation, and emergency department visits, fall under split/shared billing rules instead.

What changed with direct supervision requirements in 2026?

Effective January 1, 2026, CMS permanently adopted a definition of direct supervision that allows the supervising physician's availability to be met through real-time, two-way audio-video technology rather than requiring physical presence in the office suite, for most incident-to services. Audio-only availability does not satisfy this requirement.

Are there exceptions to the virtual supervision rule?

Yes. Services with a global surgery indicator of 010 or 090, covering minor and major procedures with bundled postoperative follow-up periods, still require the physician to be physically present on-site.

What's the difference between incident-to and split/shared billing?

Incident-to applies in office and clinic settings for established patients with existing, physician-initiated plans of care. Split/shared billing applies in facility settings when a physician and an NP jointly participate in the same encounter, with whichever practitioner performs the substantive portion billing the visit using modifier FS.

Does California's AB 890 change Medicare's incident-to billing rules?

No. AB 890 changes whether a California NP needs physician supervision to practice legally under state law, creating 103 and 104 NP designations with increasing independence. It does not change Medicare's separate, federal incident-to billing criteria, which still require an established patient, an existing physician-initiated plan of care, and direct supervision to qualify for 100 percent reimbursement.

Can a 104 NP in California still bill incident-to?

Potentially, but only for specific encounters that independently meet Medicare's incident-to criteria, meaning an established patient, a physician-initiated plan of care, and direct supervision in place for that visit. Encounters where the 104 NP is practicing with genuine independence, evaluating new problems and initiating care on her own, do not qualify for incident-to billing and should be billed under the NP's own NPI.

What triggers OIG audit attention for incident-to billing?

Common audit triggers include incident-to billing in hospital settings, billing new patient visits as incident-to, missing documentation of physician-initiated plans of care, and supervision arrangements that don't meet Medicare's current definition.

Conclusion

Incident-to billing rewards precision, not convenience. The 100 percent reimbursement rate is real, and the 2026 shift toward permanent virtual direct supervision genuinely makes compliance more workable for practices running hybrid schedules. But none of that changes the underlying test: established patient, existing problem, physician-initiated plan of care, and supervision that actually meets Medicare's current definition. For California practices, AB 890's expansion of NP independence adds a layer worth thinking through deliberately, since state scope-of-practice authority and federal billing eligibility are two different questions with two different answers.

Get Help With Incident-To Billing Compliance

Incident-to billing sits right at the intersection of clinical workflow and payer compliance, and small documentation gaps here get expensive fast, either through lost reimbursement or audit exposure. Edge RCM works with practices employing nurse practitioners and physician assistants to build billing workflows that hold up, covering documentation review, supervision compliance, split/shared billing logic, and claim submission. If your practice is navigating the 2026 supervision changes or adjusting how you bill for California NPs under AB 890, Edge RCM can help you get the structure right before a payer questions it.