Split/shared visit billing has been one of the most debated and confusing areas in critical care billing over the past several years. As healthcare regulations continue to evolve, practices that rely on critical care coding & billing services must stay updated to ensure accurate documentation, compliance, and reimbursement. CMS finalized significant rule changes that took effect in 2023, and the new framework—which determines when a physician versus an advanced practice provider (APP) can bill a critical care or hospital E/M service—is still not fully understood by many organizations.
The stakes are high. Getting split/shared billing wrong in either direction can lead to costly consequences. Billing under the physician when the APP provided the substantive portion is a compliance violation, while billing under the APP when the physician performed the key work may result in reduced reimbursement. This is why many practices rely on specialized pulmonary billing services to navigate complex CMS guidelines, minimize claim denials, and optimize revenue cycle performance. Understanding the current rules—and documenting correctly to support them—is essential for any pulmonary or critical care practice that uses physicians and APPs together in the ICU or hospital setting.
What Is a Split/Shared Visit?
A split/shared visit is an evaluation and management (E/M) service — including critical care — that is performed in part by a physician and in part by a non-physician practitioner (NPP), most commonly a nurse practitioner (NP) or physician assistant (PA), who works in the same group practice.
The key concept is that both the physician and the NPP personally perform a portion of the face-to-face service for the same patient on the same date. This is a specific and meaningful definition — it is not enough for the physician to review the APP’s note or cosign it. The physician must personally provide a substantive portion of the clinical work.
Split/shared billing rules apply to:
- Hospital inpatient E/M services (initial hospital care, subsequent hospital care, hospital discharge)
- Emergency department E/M services
- Critical care services (CPT 99291/99292)
They do not apply to outpatient office visits in a physician’s office, which have separate incident-to billing rules.
The 2023 CMS Rule Change: Substantial Portion Now Defined as History, Exam, or MDM (and Time)
Prior to the 2023 implementation, the definition of “substantial portion” for split/shared visits was vague. CMS had proposed a strict rule that the substantial portion be defined as the majority of the total time — and then walked that back before implementation.
The current rule, effective January 1, 2023, defines the “substantive portion” of a split/shared visit as one or more of the following key components:
- History
- Physical examination
- Medical decision-making (MDM)
- Or — if the service is billed on the basis of total time — the physician must personally perform more than half of the total time
This means the physician can qualify as the billing provider by personally performing the history, the exam, OR the medical decision-making — the physician does not have to perform all three. And if the visit is being billed on time, the physician must personally account for more than 50% of the total service time.
For the physician to bill the service under their own NPI, they must be the one who performed the substantive portion as defined above, and the documentation must support this.
Critical Care Split/Shared: The Specific Rules
Critical care visits have special considerations because they are time-based codes, not MDM-based. This creates a specific framework for split/shared critical care.
Option 1: Bill on the Basis of MDM
When critical care is billed based on medical decision-making (which is an acceptable basis for critical care, distinct from E/M time-based coding), the physician qualifies as the billing provider by personally performing the medical decision-making portion of the visit — reviewing the clinical situation, making management decisions, and documenting that decision-making process.
In practice, this means the physician can see the patient, review the relevant data, formulate and document the management plan, and bill the critical care service — even if the APP performed the history and physical examination.
Option 2: Bill on the Basis of Total Time
When critical care is billed based on total time (which is the most common approach, since 99291/99292 are fundamentally time-based codes), the physician must personally perform and document more than half of the total critical care time.
If the total critical care time for the encounter is 60 minutes, the physician must personally account for more than 30 minutes of that time. The APP’s time contributes to the total but the physician must provide the majority.
Important: The physician’s time and the APP’s time cannot be simultaneous. If the physician and APP are both with the patient at the same time, only one provider’s time counts for that period.
When the APP Bills Under Their Own NPI
If the physician does not perform the substantive portion of the critical care service, the service should be billed under the APP’s NPI — not under the physician’s. The APP bills independently at their own rate (which for Medicare is 85% of the physician fee schedule rate).
Billing the service under the physician’s NPI when the physician did not perform the substantive portion is a compliance violation. This is one of the scenarios that appears in OIG work plans and is a known focus of payer audits.
Documentation Requirements for Split/Shared Critical Care
The documentation requirements for split/shared visits were also clarified in the 2023 final rule. The medical record must:
- Identify both the physician and the NPP who performed the visit
- Document the role each provider played — specifically, which provider performed the substantive portion
- Include the billing provider’s attestation of which element(s) they personally performed
For a time-based critical care split/shared visit, the documentation must clearly state the total time each provider spent on critical care services for that patient on that day, so that it can be verified that the physician personally provided more than 50% of the total.
Acceptable documentation approach:
The APP documents their portion of the encounter, including history, physical examination findings, and any initial assessment. The physician then adds their own note — not a cosignature, but actual independent documentation — that records:
- The clinical elements the physician personally assessed or performed
- The management decisions the physician made
- The physician’s own time statement (for time-based billing): “I personally provided 40 minutes of critical care services for this patient today. Dr. [APP] also provided 25 minutes of critical care. As the physician who provided the majority of the total 65 minutes of critical care time, I am billing this service under my NPI.”
A cosignature alone on an APP’s note is not sufficient documentation for split/shared billing under the physician’s NPI.
Common Compliance Violations in Split/Shared Critical Care
Physician Cosigning Without Personal Participation
This is the most common split/shared billing violation. The APP manages the ICU patient, documents the encounter, and the physician cosigns the note without having personally seen the patient, performed any element of the visit, or contributed to the management decisions. The claim goes out under the physician’s NPI.
This is not a split/shared visit — it is the APP’s visit, and it should be billed under the APP’s NPI. Billing it under the physician’s NPI results in overpayment (the physician rate vs. the APP rate), which is a compliance violation subject to recoupment.
Adding a Physician Note That Only Acknowledges the APP’s Work
A physician note that says “I have reviewed the above note by NP [name] and agree with the assessment and plan” does not document personal performance of any element of the visit. It is a documentation of review, not of participation. This note does not support billing under the physician’s NPI.
Double-Counting Simultaneous Time
When the physician and APP are both present with the patient simultaneously, only one provider’s time counts for that period. A team that logs 40 minutes of APP time plus 40 minutes of physician time during a 40-minute encounter cannot claim 80 minutes of critical care time. The 40 minutes of simultaneous time counts once.
Billing 99291 Under Physician NPI When APP Provided Majority of Time
If the APP spent 50 minutes with the patient and the physician spent 20 minutes, the total qualifying physician time is 20 minutes — not enough for 99291 (which requires at least 30 minutes). The APP’s 50 minutes, billed under the APP’s NPI, supports 99291 independently. Billing 99291 under the physician NPI based on a combined 70-minute time that includes the APP’s majority contribution is incorrect.
How to Structure Your ICU Team Workflow to Maximize Compliance and Reimbursement
The practical challenge for most pulmonary and critical care practices is structuring the daily ICU workflow so that physician-APP collaboration is both clinically efficient and billingcompliant. Here are approaches that work:
Physician-Led Rounds with APP Documentation Support
The physician leads rounds, personally examines patients, makes key management decisions, and documents their own note (or a separate physician addendum). The APP documents the detailed clinical data, implements orders, and communicates with nursing. This structure naturally supports physician billing for most patients on rounds.
APP-Managed Patient Load with Defined Physician Involvement
For a larger ICU team where APPs carry a defined patient load independently, the physician provides oversight but may not perform the substantive portion for every patient. In this model, the APP bills independently for patients where the physician did not perform the substantive portion. This is the compliant approach — not billing every patient under the physician’s NPI because the physician is listed as the supervising provider.
Clear Documentation Templates
Build split/shared documentation into your EHR workflows. A split/shared visit template for the physician should include:
- A dropdown for “substantive portion performed by physician: History / Exam / MDM / Time (>50%)”
- A physician time field specifically for the physician’s own time
- A free-text field for the physician’s independent assessment and plan
- An auto-populated statement identifying both the physician and APP who participated
The Financial Impact of Getting Split/Shared Right
Split/shared billing compliance has both a downside risk and an upside opportunity.
Downside risk (overcompliance errors): If your practice is billing all ICU visits under the physician NPI without verifying that the physician performed the substantive portion, you are exposed to recoupment when a payer audits. CMS and OIG have both identified split/shared billing as an audit priority, and the recoupment risk is real.
Upside opportunity (undercompliance errors): If your practice is billing all APP visits under the APP’s NPI even when the physician regularly performs the substantive portion, you are leaving money on the table — the difference between the physician rate (100% of the fee schedule) and the APP rate (85%) on every applicable visit.
For a practice where an APP sees 20 ICU patients per day and the physician substantively participates in half of those encounters, the difference between billing those 10 at the physician rate vs. the APP rate across a full year is meaningful — potentially $50,000–$100,000 or more depending on payer mix and patient volume.
Staying Current: Rule Changes to Monitor
The split/shared billing rules have been modified multiple times in recent years, and CMS has signaled that further refinements are possible in future rulemaking cycles. Specifically:
- CMS originally proposed that “time” would be the only basis for determining the substantive portion starting in 2024, which would have significantly restricted physician billing in split/shared scenarios. This proposal has been repeatedly delayed, but it remains active rulemaking. Monitor the annual Physician Fee Schedule final rules for updates.
- Commercial payers may follow CMS rules or apply their own split/shared policies, which may differ materially. Verify each major payer’s specific policy for critical care and hospital split/shared billing.
Summary
The 2023 CMS split/shared billing rules gave practices a clearer framework for critical care team billing — but they require meaningful physician participation, clear documentation, and active compliance monitoring to apply correctly.
The core principle is straightforward: the physician can bill a critical care service only when they personally performed a substantive portion of that service, defined as the history, exam, MDM, or more than half of the total time. Everything else must be billed under the APP’s NPI.
Practices that get this right protect themselves from audit risk, collect the appropriate rate for physician services, and create a documentation culture that accurately reflects the care their team provides.
Frequently Asked Questions
What is a split/shared visit in critical care billing?
A split/shared visit is a critical care or hospital E/M service that is performed in part by a physician and in part by a non-physician practitioner (NP or PA) who works in the same group practice. For the service to be billed under the physician’s NPI, the physician must personally perform the ‘substantive portion’ of the visit — defined under the current CMS rule as performing the history, physical exam, medical decision-making, or more than half of the total time.
What is the ‘substantive portion’ requirement for critical care split/shared billing?
Under rules effective January 1, 2023, the substantive portion is defined as one or more of the following: the history, the physical examination, the medical decision-making, or — if the service is billed on total time — the physician must personally perform more than 50% of the total critical care time. The physician does not need to perform all three key components; performing any one of them satisfies the substantive portion requirement for MDM-based billing.
Can a physician cosign an APP’s note to support billing under the physician’s NPI?
No. A cosignature alone on an APP’s note does not constitute performance of a substantive portion and does not support billing the service under the physician’s NPI. The physician must personally perform a qualifying element of the visit (history, exam, MDM, or majority of time) and document that participation with their own attestation — not just a cosignature. Billing under the physician’s NPI based solely on a cosignature is a compliance violation.
If the APP provides most of the critical care, who should bill?
The service should be billed under the APP’s NPI. When the physician does not perform the substantive portion — because the APP provided the history, exam, medical decision-making, and the majority of the time — the claim must go out under the APP’s NPI at the APP’s reimbursement rate (85% of the physician fee schedule for Medicare). Billing under the physician’s NPI in this scenario results in overpayment and compliance exposure.
Can physician time and APP time be combined to reach 99291 threshold?
Only when billing on time basis and only up to the physician’s time claim. If the total critical care time is 55 minutes but the physician provided only 20 minutes, the physician cannot bill 99291 (which requires 30 minutes minimum). The APP, billing independently under their NPI, can bill 99291 based on their 35 minutes. The physician’s 20 minutes alone do not reach threshold and should be billed as an E/M service under the physician’s NPI.
What documentation is required for a split/shared critical care visit?
The medical record must: (1) identify both the physician and the APP who participated in the visit, (2) document the role each provider performed, (3) include the billing provider’s personal attestation of which substantive element they performed, and (4) for time-based billing, clearly state each provider’s individual time contribution. The physician’s note should be a separate addendum or clearly identified section — not a bare cosignature.
Are split/shared billing rules the same for all payers?
No. The rules described here reflect CMS (Medicare) guidance. Commercial payers and Medicare Advantage plans may follow CMS rules or apply their own split/shared policies, which can differ materially. Some commercial payers have more restrictive rules about when a service can be billed under a physician’s NPI in a shared care scenario. Always verify each major payer’s specific policy for critical care and hospital split/shared billing.