Split-shared visits occur when a physician and an advanced practice provider (APP: nurse practitioner or physician assistant) both participate in the same patient encounter during the same calendar day in a facility setting. Facility settings for split-shared purposes include hospital inpatient, hospital outpatient department, and skilled nursing facility. Office-based visits with APP involvement follow separate rules (incident-to billing).
Cardiology teams commonly work in split-shared arrangements in hospital settings: a cardiology APP performs the initial evaluation, and the attending cardiologist reviews and completes the encounter. Correctly applying the substantive-portion rule preserves the higher physician-level payment when appropriate and correctly bills under the APP when the APP owned the encounter.
The substantive-portion rule
CMS has finalized rules defining the substantive portion of a split-shared visit. The definition depends on the coding methodology chosen:
Time-based coding
Under time-based coding, the substantive portion is defined as more than half of the total time spent on the encounter. Total time includes all activities the physician and APP performed on the encounter date related to the visit.
Example: If the total encounter time is 45 minutes and the physician spent 25 minutes and the APP spent 20 minutes, the physician performed the substantive portion (more than half) and the visit is billed under the physician's NPI. If the physician spent 20 minutes and the APP spent 25 minutes, the visit is billed under the APP's NPI.
MDM-based coding
Under MDM-based coding, the substantive portion is defined as the meaningful decision-making component of the visit. This typically requires the physician to have made the substantive medical decisions during the encounter, not merely reviewed the APP's assessment.
Documentation should reflect the physician's independent decision-making: which diagnoses were established, which management decisions were made, and which prescriptions or orders were initiated by the physician versus the APP.
Payment implications
Medicare pays APP services at 85% of the physician rate. Billing under the physician's NPI captures the full physician rate; billing under the APP's NPI captures 85%. On a typical cardiology follow-up visit (99213-99215), the difference ranges from $10-$30 per visit depending on level.
On a busy cardiology inpatient service performing several thousand encounters annually, correct split-shared application preserves substantial revenue. Practices incorrectly billing under APP when the physician performed the substantive portion undercharge; practices incorrectly billing under physician when the APP performed the substantive portion overcharge and face audit exposure.
Documentation requirements
Split-shared documentation should establish:
Which practitioners participated
- Physician name and NPI
- APP name and NPI
- Encounter date and location (facility type)
Time contribution (if time-based)
- Physician time on encounter
- APP time on encounter
- Total encounter time
- Explicit statement that the physician (or APP) performed the substantive portion
MDM contribution (if MDM-based)
- Which practitioner established diagnoses
- Which practitioner made management decisions
- Which practitioner ordered tests or prescriptions
- Explicit statement that the physician (or APP) performed the substantive medical decision making
Signature
Both practitioners typically sign the encounter note when both participated. The billing NPI reflects the practitioner who performed the substantive portion.
Common documentation failures
Failure to identify time contribution
A note stating "Dr. Smith saw the patient with NP Jones" without time attribution cannot support physician billing under time-based rules. Auditors default to APP-rate billing when time is not documented.
Physician co-signature without independent participation
A note showing the APP performed the entire encounter with the physician signing as co-signer does not qualify as split-shared. The physician must have actively participated in the encounter during the same calendar day. Passive co-signature is not sufficient.
Ambiguous decision-making
Under MDM-based rules, a note that shows the physician reviewed the APP's assessment without documenting independent decision-making cannot support physician-level billing. The physician's own diagnostic conclusions, management plans, and orders should be documented.
Audit risk profile
Split-shared billing is a known audit focus area. CMS Targeted Probe and Educate cycles have included split-shared review, and RACs have identified split-shared documentation gaps as a recovery target. The audit pattern typically identifies practices with high physician-billing rates on visits that appear on documentation review to have been APP-owned.
Defensive documentation includes:
- Consistent time attribution on every split-shared visit
- Contemporaneous documentation (written at the time of service, not added later)
- Clear identification of which practitioner performed which decision-making elements
- Encounter notes that stand on their own without cross-reference to other documents
Team workflow considerations
High-performing cardiology teams working in split-shared arrangements typically establish:
- Standard note templates that prompt for time attribution and MDM ownership
- Clear team protocols for when the physician versus APP performs the substantive portion
- Real-time discussion between physician and APP about billing pathway on complex cases
- Periodic internal audit of split-shared billing patterns against documentation
The workflow discipline prevents both under-billing (missed physician revenue on physician-owned encounters) and over-billing (audit exposure on APP-owned encounters billed under physician).