A split/shared E/M claim can fail even when both clinicians provided appropriate care. The common problem is not the clinical service. It is the inability to calculate split shared visit time correctly, identify the practitioner who performed the substantive portion, and support that decision in the record. For Medicare claims, those details determine whose NPI belongs on the claim and whether the billed E/M service can withstand payer review.
This is not an administrative cleanup task after the encounter. It is a documentation and charge-capture decision that should be resolved before the claim is released.
When split/shared billing applies
For Medicare, split/shared E/M billing generally applies when a physician and nonphysician practitioner, such as an NP or PA, in the same group and same specialty perform a qualifying E/M service in a facility setting. The service is reported under the NPI of the practitioner who performed the substantive portion of the encounter.
That setting requirement matters. A service in the office does not become a Medicare split/shared visit merely because both a physician and an NPP participated. Practices should not use facility split/shared logic to move an office claim to the physician’s NPI. If the practice is considering incident-to billing, that is a separate framework with separate supervision, established-plan, and setting requirements.
Coders should also distinguish split/shared E/M services from critical care, procedures, and services governed by their own billing rules. A physician’s brief review of a case, signature on an NPP note, or agreement with an assessment does not automatically create a billable split/shared service.
The time calculation that determines the billing practitioner
When time is used to establish the substantive portion, the billing practitioner must personally perform more than half of the total qualifying time spent by both practitioners. More than half is the key standard. Exactly half is not enough.
Use this calculation:
`Billing practitioner time > total distinct qualifying time ÷ 2`
The total is the combined, distinct time of the physician and NPP on the date of service. The word distinct is where many calculations break down. Do not count the same activity twice simply because both clinicians were present.
For example, an NPP spends 22 minutes performing a history, examination, care coordination, and documentation. The physician then spends 24 separate minutes evaluating the patient, reviewing results, discussing the plan, and documenting medical decision-making. Their combined distinct time is 46 minutes. More than half is greater than 23 minutes. Because the physician personally spent 24 minutes, the physician may be the billing practitioner when the time-based substantive-portion standard applies.
Now change the numbers. If the NPP spends 23 minutes and the physician spends 23 minutes, total time remains 46 minutes. Neither practitioner spent more than half. The physician cannot bill simply because the physician signed the note or saw the patient last. The organization must apply the applicable substantive-portion policy in effect for that date of service, which may allow another qualifying method, or bill under the practitioner who meets the policy requirements.
Do not double-count joint time
Joint work is a frequent audit vulnerability. If the physician and NPP spend six minutes together at the bedside discussing the plan with the patient, those six minutes can be counted once in the total. They cannot be counted as six physician minutes and six NPP minutes.
The record should make clear who is claiming that time for substantive-portion purposes. A vague statement such as seen and examined with APP does not establish individual time or prevent duplication. When a practice relies on time, its note design should identify each practitioner’s separately performed work and time, along with any jointly performed time counted once.
Separate the substantive-portion test from E/M level selection
The calculation serves one major purpose: determining which clinician may submit the split/shared claim under that clinician’s NPI. It does not erase the normal E/M code-selection rules.
Depending on the E/M code family and applicable Medicare policy, the level of service may be selected using medical decision-making or total time. If total time is used to select the E/M level, the underlying activities must be qualifying E/M work and supported by the documentation. Time spent on separately reported services, travel, or unrelated tasks cannot be added merely to reach a higher level.
This creates two questions coders should answer independently:
- What supports the E/M level: medical decision-making or qualifying total time?
- Which practitioner performed the substantive portion and should be listed as the billing practitioner?
Those answers may both involve time, but they are not interchangeable. A compliant level of service does not solve an unsupported billing-NPI decision.
What the documentation should show
A defensible split/shared note does not need unnecessary narrative. It does need enough specificity to demonstrate the work of each practitioner. The strongest documentation identifies the practitioners, states their distinct contributions, records their individual times when time is being used, and shows the clinical work that supports the reported E/M service.
For the physician, that may include the independent evaluation of the patient, interpretation of clinical data, risk-focused discussion, changes to treatment, and direct communication with the patient or family. For the NPP, it may include the initial assessment, review of interval history, examination, coordination with consultants, counseling, and documentation of the care plan. The note should reflect what actually occurred, not a reconstructed division of labor designed after charge review.
Templates can help, but a template alone is not protection. A default attestation that the physician performed the substantive portion creates risk when no individualized time or medical decision-making contribution supports it. Auditors will compare the attestation with timestamps, note content, orders, nursing documentation, and the overall encounter timeline.
The policy timing issue coders should watch
Medicare has revised its approach to the substantive portion through annual rulemaking and transition policies. Practices should not assume that a prior year’s flexibility applies indefinitely or that every payer follows Medicare’s approach.
Before finalizing a workflow, confirm the policy effective for the specific date of service, including whether the payer permits substantive medical decision-making, requires more than half of total time, or applies a different rule. Medicare Advantage plans and commercial payers may publish their own billing instructions. A revenue-cycle team that uses one broad split/shared rule for every payer invites avoidable denials and post-payment findings.
Build this verification into annual charge-description-master and education updates. The same calendar that drives CPT, HCPCS, and ICD-10-CM readiness should also trigger a review of E/M, split/shared, and NPP billing workflows.
A practical pre-bill review process
Before submitting a split/shared claim, the coder or charge-review team should confirm the facility setting, same-group and same-specialty relationship, qualifying E/M code family, and payer-specific policy. Next, identify whether time or medical decision-making is being used for the substantive-portion determination. If time is the basis, total the distinct qualifying minutes, calculate the halfway point, and verify that the proposed billing practitioner exceeded it.
Then compare the result to the note. The practitioner named on the claim should match the practitioner supported by the documentation. If the evidence is incomplete, do not solve the problem by choosing the higher-paying NPI. Route the encounter for a compliant clarification or bill it under the practitioner whose work is clearly supported, consistent with payer rules.
The most reliable split/shared workflow is simple: document individual work while the encounter is fresh, count each minute once, and make the billing-NPI decision before the claim becomes a denial or audit defense problem.
