CurrentPremera BluecrossPolicy N/A

Modifier AS — Non-Physician Assistant-at-Surgery (PA, NP, CNS) Services

Defines when Premera recognizes and reimburses assistant-at-surgery services billed with modifier AS for physician assistants, nurse practitioners, or clinical nurse specialists on professional claims (CMS-1500 / 837P) and the related billing and documentation requirements.

Policy Summary

PayerPremera Bluecross

PolicyModifier AS — Non-Physician Assistant-at-Surgery (PA, NP, CNS) Services

Policy CodePolicy N/A

Change TypeDocumentation and coverage clarifications

Effective DateJun 12, 2025

Next Review DateAug 12, 2024

Key ActionIf a procedure's NPFS assistant-at-surgery indicator is '0', submit documentation demonstrating the need for the assistant and the specific services rendered with the claim.

SourceLink

POLICY UPDATE CHANGES

Removed Oregon exception for reimbursement percentage from the exceptions section.

Clarified that operative reports must document the specific services the non-physician assistant rendered rather than merely noting presence.

Stated that when a surgical procedure has a CMS NPFS assistant-at-surgery indicator of 0, documentation of need for an assistant must accompany the claim.

10%Standard reimbursement percentage of primary surgery allowed amount for non-physician assistant-at-surgery

13%Alaska reimbursement percentage

1Allowed assistant surgeon per applicable surgical procedure

Policy Summary

PayerPremera Bluecross

PolicyModifier AS — Non-Physician Assistant-at-Surgery (PA, NP, CNS) Services

Policy CodePolicy N/A

Change TypeDocumentation and coverage clarifications

Effective DateJun 12, 2025

Next Review DateAug 12, 2024

Key ActionIf a procedure's NPFS assistant-at-surgery indicator is '0', submit documentation demonstrating the need for the assistant and the specific services rendered with the claim.

SourceLink

On This Page

Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

Coverage criteria for Modifier AS services

Modifier AS coverage criteria

Covered when ALL of the following are met:

Only procedure codes eligible for assistant surgeons per the CMS National Physician Fee Schedule Assistant Surgeon indicator will be reimbursed without additional documentation.

When the surgical procedure's NPFS Assistant Surgeon indicator is '0', the claim must include documentation demonstrating the need for a surgical assistant and must identify the specific service(s) the non-physician assistant rendered (mere presence is insufficient).

The non-physician assistant surgeon must report the same procedure code as the primary surgeon appended with modifier AS and must submit the assisting provider's own NPI on the claim.

Modifier AS must not be billed with modifiers 80, 81, or 82 on the same claim, by the same provider, or on the same date of service; only one assistant surgeon is allowed per applicable surgical procedure unless billed as a surgical team (modifier 66).

If multiple non-physician providers or other highly skilled personnel are required for a highly complex procedure, bill as a surgical team using modifier 66 and each provider's documentation must define their role; when two surgeons act as primary surgeons performing distinct or simultaneous parts of the procedure, use modifier 62 (Two Surgeons) and each surgeon must create their own operative report (they are not assistants).

Reimbursement: standard reimbursement is 10% of the provider's applicable Fee Schedule allowed amount for the primary surgery (Alaska exception: 13%); this policy does not apply to providers reimbursed under ASC APC methodology.

Violations of this policy may result in increased auditing and monitoring, contractual penalties, or termination of contract at the Plan's discretion.

Modifier, team/co-surgeon, and assistant eligibility coding

Modifier and team/co-surgeon codingModifier

Modifier AS	Used to report assistant-at-surgery services provided by PA, NP, or CNS (non-physician).
Modifiers 80/81/82	Assistant surgeons (physician) — must not be used by physician providers for AS services; cannot be billed with Modifier AS on same claim/date/provider.
Modifier 66	Surgical Team — use when multiple non-physician providers/highly skilled personnel are required for a highly complex procedure.
Modifier 62	Two Surgeons (co-surgeons) — use when two surgeons act as primary surgeons performing distinct/simultaneous parts of the procedure.

Assistant eligibility per NPFS indicator

Eligibility based on NPFS Assistant Surgeon indicatorOnly procedure codes eligible for assistant surgeons per the CMS National Physician Fee Schedule Assistant Surgeon indicator will be reimbursed without additional documentation; if the NPFS indicator is '0', documentation demonstrating the need for a surgical assistant and the specific services rendered must accompany the claim.

Billing requirement when eligibleThe non-physician assistant must report the same procedure code assisted by the primary surgeon appended with modifier AS and include the assistant's own NPI on the claim.

Modifier usage restrictionModifier AS must not be billed with modifiers 80, 81, or 82 on the same claim by the same provider on the same date of service.

Number of assistants allowedOnly one assistant surgeon is allowed per applicable surgical procedure unless services are billed as a surgical team using modifier 66.

Prior authorization, documentation, and billing rules

Prior Authorization

Prior authorization / documentation and billing rules

Prior authorization is not specifically required by this policy, but when the CMS NPFS Assistant-at-Surgery indicator = "0" for a procedure, the claim must include documentation supporting the medical necessity of a surgical assistant. The operative report must state why a non‑physician assistant-at‑surgery was needed and the specific services rendered. Failure to submit required documentation when Indicator = "0" may result in denial or payment adjustment.

Applicable when CMS NPFS Assistant-at-Surgery indicator = "0" — include documentation of need and specific assistant services
Do not use modifier AS when the non‑physician is only an extra set of hands (not acting as a surgical assistant)
Modifier AS must not be billed with modifiers 80, 81, or 82 on the same claim/date/provider
Only one assistant surgeon allowed per procedure unless billed as modifier 66 (Surgical Team) with each team member’s role documented
All non‑physician assistant-at-surgery claims must include the assisting provider’s NPI on the claim

Definitions used in this policy

Non-physician assistant-at-surgery (definitions)

Physician Assistant (PA)Non‑physician practitioner who may assist in surgery, reports services with their own NPI and appropriate place of service; capable of taking over the surgery if primary surgeon becomes incapacitated.

Nurse Practitioner (NP)Advanced practice practitioner who may assist in surgery and is reported as a non‑physician assistant-at-surgery with their own NPI on claim submissions.

Clinical Nurse Specialist (CNS)Advanced practice practitioner who may assist in surgery and is reported as a non‑physician assistant-at-surgery with their own NPI on claim submissions.

Surgical Team (modifier 66)

Modifier 66 — Surgical TeamUse when the services of more than one non‑physician provider or other highly skilled, specially trained personnel are required for a highly complex procedure; each provider's documentation should define the role they played as part of the surgical team.