Split or Shared Visits: What Substantive Portion Means Now
For a split (or shared) visit, the substantive portion is what decides which of two clinicians reports the encounter, and the regulation defines it as more than half of the total time spent by the physician and the non-physician practitioner performing the visit, or a substantive part of the medical decision making. Critical care visits are the exception and are decided on time alone. That has been the rule since January 1, 2024, and — despite how much of the internet still describes it as pending — it has not changed since.
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Key takeaways
- Two ways to qualify: more than half the total time, or a substantive part of the medical decision making. Either one is sufficient.
- History and exam no longer qualify on their own. Under the 2022–2023 transitional rule any one of the three could carry the visit; since January 1, 2024 only time and medical decision making can.
- Critical care is time only, because those codes do not use medical decision making.
- The rule stopped moving. CMS announced a time-only definition twice, deferred it twice, then abandoned it — and 42 CFR 415.140 has not been amended since that January 1, 2024 change.
- Two conditions travel with it: the clinician who performed the substantive portion signs and dates the record, and modifier FS goes on the claim.
The definition in force
The rule lives in one regulation, 42 CFR 415.140, and the definition sits in its paragraph (a) alongside the definitions of the two other terms the section depends on. Payment is made to whichever clinician performed the substantive portion, and that clinician reports the visit under their own identifier — which is why the question is worth getting exactly right rather than approximately right.
- The general test
- More than half of the total time spent by the physician and the non-physician practitioner performing the split (or shared) visit, or a substantive part of the medical decision making. The two limbs are alternatives; satisfying either one is enough, and there is no requirement to satisfy both or to pick one in advance.
- The critical care exception
- For critical care visits, the substantive portion means more than half of the total time, and nothing else. The regulation carves these out because the critical care codes do not use medical decision making at all, so the second limb has nothing to attach to.
- Total time means both clinicians' time
- The denominator is the time spent by the physician and the non-physician practitioner together performing the visit. The test is a share of that combined figure, not a threshold either clinician meets on their own.
This decides who reports the visit, not what level it is
What quietly stopped qualifying
The change that catches practices is not what was added but what was removed. When CMS first wrote this rule it allowed any one of the three classic evaluation and management elements to carry the visit. The current definition does not.
| Basis | CY 2022 – CY 2023 | From January 1, 2024 |
|---|---|---|
| More than half the total time | Qualified | Qualifies |
| Medical decision making | Qualified, as one of the three key components | Qualifies, as a substantive part of it |
| History | Qualified on its own | Does not qualify |
| Examination | Qualified on its own | Does not qualify |
| Critical care visits | Time only | Time only — unchanged |
The transitional wording was explicit that it applied to visits furnished in calendar year 2022 and 2023. It expired by its own terms; nothing had to be repealed for it to stop applying.
The failure mode is silent
Why it still feels unsettled, and why it is not
Almost every secondary source on this topic reads as though a change were imminent, and that impression is a residue of what happened between 2021 and 2023 rather than a description of anything happening now.
2021 — the rule is created, with a phase-in
CMS establishes the section in the CY 2022 final rule. For CY 2022 the substantive portion may be any one of the three key components or more than half the total time, and CMS states that the full time-only definition will take effect the following year.2022 — the time-only definition is deferred
After sustained objections that a time-only rule would disrupt team-based practice and require new time-tracking systems, CMS delays implementation to January 1, 2024.2023 — CMS proposes to defer it again
The proposed rule would have pushed the time-only definition through at least the end of CY 2024, keeping the three-component option alive for another year.2023 — and then abandons it instead
In the final rule CMS does not delay again. It drops the time-only policy, aligns the definition with the revised evaluation and management guidelines, and adopts the permanent time-or-medical-decision-making test that is in force today. CMS gives its reason plainly: to stop facilities spending time and resources preparing for policy changes that are delayed year after year.2024 to now — nothing
The section has not been amended since that change took effect. The phrase does not appear in the CY 2025 final rule, the CY 2026 final rule, or the CY 2027 proposed rule.
The practical consequence is a dating rule for anything you read about this. Material written in 2022 or 2023 describes a definition that expired. Material written in anticipation of the time-only rule describes a policy that was never implemented. The regulation's own amendment history is the fastest way to check: it names the last date the text changed, and for this section that date is January 1, 2024.
The two conditions that travel with it
Getting the attribution right is necessary and not sufficient. The regulation attaches two more conditions of payment, and both are things that happen where the claim is built rather than where the care is delivered.
- The record identifies both, and one of them signs
- Documentation must identify the physician and the non-physician practitioner who performed the visit. The individual who performed the substantive portion — and who therefore bills it — must sign and date the medical record. A record that shows the work but not who signed for it does not meet the condition.
- The claim carries the designated modifier
- The regulation requires a designated modifier identifying the service as a split (or shared) visit. That modifier is
FS, a HCPCS Level II modifier CMS created for the purpose, and it is reported whether the physician or the non-physician practitioner bills the visit.
FS does not change what is paid
One related boundary is worth knowing because people reach for it: Medicare does not pay for partial evaluation and management visits, and the reduced-services modifier cannot be used to report one. A split or shared visit is a complete visit performed by two people, not two partial visits, and there is no mechanism for billing it as a fraction.
When the rule applies at all
Before any of the above matters, the encounter has to be a split (or shared) visit as the regulation defines it. Three conditions have to hold together, and if any one fails, this definition is simply not the question.
- A facility setting. The regulation defines this by cross-reference rather than by listing places: a facility setting is an institutional setting where incident-to billing is unavailable. The incident-to rule requires a noninstitutional setting, so the two regimes are complementary by construction — where one applies, the other cannot, and there is no overlap to choose between.
- A physician and a non-physician practitioner in the same group. Two physicians sharing a visit is not this rule. Nor is a physician and a practitioner outside the group.
- A service either of them could have billed alone. The visit has to be one that, if furnished independently by only one of them, that person could have billed under applicable law. If the non-physician practitioner could not have billed it independently, there is nothing to split.
The office is the other side of the line
Common questions
What is the substantive portion of a split or shared visit right now?
More than half of the total time spent by the physician and the non-physician practitioner performing the visit, or a substantive part of the medical decision making. Either one is sufficient. For critical care visits it is time alone, because those codes do not use medical decision making. This has been the definition since January 1, 2024 and 42 CFR 415.140 has not been amended since.
Did the time-only rule ever take effect?
No. CMS finalized it in the CY 2022 rule with a phase-in, delayed it to January 1, 2024 in the CY 2023 rule, proposed to delay it again for CY 2024, and then in the CY 2024 final rule abandoned it and adopted the current time-or-medical-decision-making definition instead. Guidance written while the time-only rule was pending describes a policy that never governed a single claim.
Can the physician qualify by performing the examination or taking the history?
Not any more. Between 2022 and 2023 any one of history, examination or medical decision making would qualify, and that transitional wording applied by its terms only to visits furnished in those two calendar years. Since January 1, 2024 the only two bases are time and medical decision making. An attribution rule built around who examined the patient no longer matches the regulation, and it will keep producing claims that pay until someone reviews the record.
Which modifier identifies a split or shared visit?
Modifier FS, a HCPCS Level II modifier CMS created for this purpose. The regulation makes reporting the designated modifier a condition of payment, and it is appended whether the physician or the non-physician practitioner bills the visit. It does not change what the line pays — CMS created it so that shared visits could be identified from claims data rather than only through medical record review.
Does this apply to visits in the office?
No. The rule is confined to facility settings, which the regulation defines as the institutional settings where incident-to billing is unavailable. Because the incident-to rule requires a noninstitutional setting, the two frameworks cannot both apply to the same encounter. In an office, the question is whether the incident-to conditions are met, not who performed the substantive portion.
Do commercial payers use this definition?
Not necessarily. This is a Medicare condition of payment set by regulation. Medicare Advantage plans and commercial payers may apply their own attribution rules or may not recognize shared billing at all, and a plan that follows Medicare on the definition may still differ on the modifier or the documentation. Confirm it against the specific payer's policy rather than assuming it tracks the regulation.
Key terms in this article
Defined once, on their own pages.
Continue learning
Where to go next.
Incident-to vs. split/shared billing
The other half of the pair: which framework applies, and how their conditions differ once you know.
How a modifier changes adjudication
Why most modifiers move money and why modifier FS is the kind that does not.
Time-based billing units
What counts as time when time is the measure, and where the counting rules come from.
Modifier order on a claim line
Where an identification modifier like FS sits when the line already carries others.
Professional claim release checklist
The controls to clear before a professional claim goes out, including the modifier and the signature.
Authoritative sources
- 42 CFR § 415.140 — Conditions for payment: split (or shared) visits (opens in a new tab)
The whole rule in one section: the definition of substantive portion and its critical care carve-out at paragraph (a), and the three conditions of payment at (b) — payment follows the substantive portion, the record identifies both clinicians and is signed by the one who bills, and the designated modifier appears on the claim. Read against the eCFR issue of August 5, 2026; the section's own version history records its last amendment as January 1, 2024.
- CY 2024 Physician Fee Schedule final rule, 88 FR 78818 (at 78983–78985) (opens in a new tab)
Where CMS abandoned the time-only definition rather than delaying it a third time, adopted the current time-or-medical-decision-making test, kept critical care on time because those codes do not use medical decision making, and named modifier FS. It also states the reason: to stop facilities preparing for policy changes that are delayed year after year.
- CY 2022 Physician Fee Schedule final rule, 86 FR 64996 (at 65152–65159) (opens in a new tab)
The origin of the rule: the phased definition that allowed any one of the three key components for CY 2022, the signature requirement now codified at 415.140(b)(2), the decision to require a claim modifier so that shared visits could be identified without a record review, and the clarification that Medicare does not pay for partial E/M visits and the reduced-services modifier cannot report one.
- 42 CFR § 410.26 — Services and supplies incident to a physician's professional services (opens in a new tab)
The section that decides where the split (or shared) rule applies at all. Paragraph (b)(1) requires incident-to services to be furnished in a noninstitutional setting to noninstitutional patients, and § 415.140 defines its own facility setting by pointing back at that requirement — which is why the two frameworks cannot overlap.