Under Medicare’s split or shared visit rules, when a physician and a non-physician practitioner from the same group each perform part of a single evaluation and management encounter in a facility setting, whichever one performs the substantive portion bills the entire visit under their own National Provider Identifier. The substantive portion is measured either by time (more than half of the combined distinct time) or by medical decision-making, with a narrower time-only rule for critical care. Payment lands at 100 percent of the fee schedule when the physician bills and 85 percent when the NPP bills, which is why the substantive portion determination matters on every claim.
When the Rule Applies
Federal regulations define a split or shared visit as an E/M service performed partly by a physician and partly by an NPP from the same group practice, where either practitioner could have independently billed the service alone.1eCFR. 42 CFR 415.140 – Conditions for Payment: Split (or Shared) Visits Three NPP categories qualify: nurse practitioners, physician assistants, and clinical nurse specialists.2Social Security Administration. Social Security Act Title XVIII Section 1861
Two structural limits control whether the framework applies at all. Both practitioners must belong to the same group; a physician and an NPP from different groups who happen to see the same patient on the same day cannot combine their work into a single claim. And the encounter must take place in a facility setting, which CMS defines as an institutional environment where “incident to” billing is not permitted. In practice that means inpatient hospital departments, hospital outpatient departments, and emergency departments. Office visits and nursing facility visits are out.3Centers for Medicare & Medicaid Services. Updates for Split or Shared Evaluation and Management Visits
Who Bills: The Substantive Portion
The central question in every split or shared visit is who performed the substantive portion. The regulation offers two ways to answer it for most E/M visits: total time or medical decision-making.1eCFR. 42 CFR 415.140 – Conditions for Payment: Split (or Shared) Visits
Time
Under the time method, whichever practitioner spends more than half of the combined time on the encounter is the billing provider. A physician who spends 30 minutes on a visit while the NPP spends 20 minutes has performed more than half of the 50-minute total and bills the visit. Reverse the numbers and the NPP bills instead.
Only distinct time counts. When the physician and NPP are jointly present with the patient or are discussing the case together, that time can be counted only once toward the total.4Centers for Medicare & Medicaid Services. Medicare Claims Processing Manual – Split (or Shared) Visits Ten minutes in the room together does not become twenty. Teams billing on time need to track individual, non-overlapping minutes to know who actually crossed the halfway line.
Medical Decision-Making
Alternatively, the practitioner who performs the substantive part of the medical decision-making can bill the visit regardless of how time was divided. MDM here follows the CPT E/M guidelines and their three elements: the number and complexity of problems addressed, the amount and complexity of data reviewed, and the risk associated with management decisions.3Centers for Medicare & Medicaid Services. Updates for Split or Shared Evaluation and Management Visits
Both practitioners can contribute to different aspects of MDM, but the billing practitioner must own the substantive part. In practice, that usually means the provider who determines the diagnosis, weighs the treatment options, and takes responsibility for the management plan. Unlike the time method, there is no bright-line percentage; the analysis follows the CPT codebook.
Having both options lets teams reflect their actual workflow honestly. In a busy emergency department, an NPP may spend the majority of minutes with a patient while a physician makes the critical diagnostic and treatment calls in a shorter encounter. That physician can bill under MDM even though the NPP logged more time.
Critical Care and Prolonged Services
Critical care is the important exception. For CPT codes 99291 and 99292, the substantive portion is determined solely by time; MDM is not available as an alternative.5Centers for Medicare & Medicaid Services. Evaluation and Management Services (MLN006764) Whichever practitioner spends more than 50 percent of the combined critical care time bills the service. Prolonged services follow the same time-only logic because they are defined by time in the first place.3Centers for Medicare & Medicaid Services. Updates for Split or Shared Evaluation and Management Visits
For critical care, combined time from both practitioners must reach at least 30 minutes before the service can be billed. Report 99291 for the first 30 to 74 minutes, then add units of 99292 for each additional 30-minute block once cumulative time reaches 104 minutes or more.5Centers for Medicare & Medicaid Services. Evaluation and Management Services (MLN006764) The FS modifier still applies.
Filing the Claim: FS Modifier and Payment Rates
The claim goes out under the NPI of the practitioner who performed the substantive portion. That NPI goes in the rendering provider field of the CMS-1500 form or its electronic equivalent. To identify the encounter as split or shared, append modifier FS to the E/M procedure code.3Centers for Medicare & Medicaid Services. Updates for Split or Shared Evaluation and Management Visits Without the modifier, Medicare processes the claim as an ordinary visit, which can produce payment discrepancies and invite post-payment review. Critical care and prolonged service codes take the same FS modifier when billed as split or shared.5Centers for Medicare & Medicaid Services. Evaluation and Management Services (MLN006764)
Payment depends on who bills. When the physician performs the substantive portion and bills the visit, the claim pays at 100 percent of the Medicare Physician Fee Schedule.3Centers for Medicare & Medicaid Services. Updates for Split or Shared Evaluation and Management Visits When the NPP bills, the claim pays at 85 percent. That 15-point spread adds up across a high-volume practice, and it is exactly why CMS scrutinizes the documentation behind physician-billed claims.
What the Record Has to Show
The medical record must identify both the physician and the NPP who participated in the visit, meaning each practitioner’s name and credentials belong somewhere in the chart for that encounter.1eCFR. 42 CFR 415.140 – Conditions for Payment: Split (or Shared) Visits The practitioner who performed the substantive portion, and who therefore bills the visit, must sign and date the record.4Centers for Medicare & Medicaid Services. Medicare Claims Processing Manual – Split (or Shared) Visits Only the billing provider’s signature is required by the regulation.
When time is the basis for billing, the record should reflect the individual, non-overlapping minutes each practitioner spent. CMS does not require a specific format, but documentation vague enough to hide who actually did what is documentation that invites downcoding. “I spent the majority of time” is weaker than “I spent 25 minutes reviewing data, examining the patient, and coordinating care.”
When MDM is the basis, the notes should make plain which practitioner assessed the problems, reviewed the data, and settled the management plan. Auditors look for a logical connection between the documented clinical reasoning and the identity of the billing provider. A detailed NPP note paired with a one-line physician co-signature is the pattern that draws recoupment demands.
Split or Shared vs. “Incident To”
These two frameworks get confused constantly, and mixing them up produces denied claims. The dividing line is setting. Split or shared visits happen in facility settings. “Incident to” billing applies in office and clinic settings, where an NPP provides services under a physician’s direct supervision.6Centers for Medicare & Medicaid Services. Incident To Services and Supplies
“Incident to” carries stricter conditions than the split or shared rules. The physician must have personally performed the initial service for the patient’s course of treatment, must stay actively involved in ongoing care, and must be present in the office suite while the NPP delivers the service.6Centers for Medicare & Medicaid Services. Incident To Services and Supplies When those conditions are met, the claim bills under the physician’s NPI at 100 percent. Split or shared visits require none of that: either practitioner can see the patient first, and physical presence in the suite is not the test. The only question is who performed the substantive portion of that specific encounter.
What Goes Wrong When It Goes Wrong
Improper split or shared billing reaches past a single denied claim. Medicare Administrative Contractors can demand repayment after post-payment review, and ambiguous documentation about who performed the substantive portion is one of the most common downcoding and recoupment triggers.
At the serious end, systematically billing under the physician’s NPI when the NPP actually performed the substantive portion can amount to a false claim. The federal False Claims Act carries per-claim penalties and treble damages, and the HHS Office of Inspector General can pursue civil monetary penalties or program exclusion. E/M billing patterns, including split or shared services, have appeared repeatedly on OIG audit priorities.
Contemporaneous documentation of each practitioner’s role, periodic internal audits of split or shared claims, and training on the distinct time rule and MDM attribution are the practical steps that hold up under review. The cost of an internal audit is small next to two years of overbilled claims paid back with interest.