CurrentPremera BluecrossPolicy N/A

Modifier AS — Physician Assistant, Nurse Practitioner or Clinical Nurse Specialist Services for Assistant at Surgery (Non-Physician)

Defines when Premera recognizes Modifier AS for physician assistants, nurse practitioners, or clinical nurse specialists assisting at surgery and how such services are billed and reimbursed for applicable Premera and affiliated lines of business.

Policy Summary

PayerPremera Bluecross

PolicyModifier AS — Physician Assistant, Nurse Practitioner or Clinical Nurse Specialist Services for Assistant at Surgery (Non-Physician)

Policy CodePolicy N/A

Change TypeClarification and specification of billing and documentation requirements

Effective DateAug 4, 2011

Next Review DateN/A

Key ActionSubmit claims with Modifier AS and include the assisting provider's own NPI; provide supporting documentation when CMS NPFS indicator = 0.

SourceLink

POLICY UPDATE CHANGES

In the Policy section, clarified that the assistant surgeon must bill the same procedure code, appended with a surgical assist modifier, as the primary surgeon.

Clarified that when two surgeons act as primary surgeons performing distinct or simultaneous parts of a procedure they are co-surgeons and modifier 62 should be used rather than assistant-at-surgery modifiers.

Specified that the assisting provider's own NPI must be on the assistant-at-surgery claim.

Removed Oregon providers exception reimbursing assistants at 20% of the primary surgery fee schedule amount.

10%standard reimbursement rate of assistant-at-surgery for non-Alaska providers

13%reimbursement rate for Alaska providers

1only one assistant surgeon allowed per applicable procedure

CMS NPFSuses Assistant Surgeon indicator from CMS NPFS

Modifier ASmodifier required for non-physician assistant-at-surgery services

Modifier AS Coverage Criteria

Modifier AS coverage criteria

Covered when ALL of the following are met:

Modifier AS must be appended to the same procedure code billed by the primary surgeon when appropriate (or the specific surgery-only code if the primary surgeon billed a global code).

The non-physician assistant-at-surgery must actively assist the surgeon and participate in the actual performance of the procedure; the operative report must document the reason the assistant's services were needed and the specific services rendered.

Only procedures eligible per the CMS National Physician Fee Schedule 'Assistant Surgeon' indicator will be reimbursed: Indicator 2 = payable; Indicator 1 = statutory restriction (not payable); Indicator 9 = concept does not apply; Indicator 0 = payment restriction unless supporting documentation of medical necessity and specific services rendered is submitted.

Modifier AS must not be used if the non-physician (PA, NP, CNS) served merely as an 'extra' pair of hands and did not function as a surgical assistant.

Policy Summary

PayerPremera Bluecross

PolicyModifier AS — Physician Assistant, Nurse Practitioner or Clinical Nurse Specialist Services for Assistant at Surgery (Non-Physician)

Policy CodePolicy N/A

Change TypeClarification and specification of billing and documentation requirements

Effective DateAug 4, 2011

Next Review DateN/A

Key ActionSubmit claims with Modifier AS and include the assisting provider's own NPI; provide supporting documentation when CMS NPFS indicator = 0.

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.

Relevant Modifiers, Roles, and Billability

Relevant modifiers and rolesModifier

Modifier AS	Physician Assistant, Nurse Practitioner or Clinical Nurse Specialist services for assistant-at-surgery (non-physician)
Modifier 80/81/82	Assistant surgeons (physician) — not to be used by non-physician assistant on same claim/date
Modifier 62	Two surgeons — co-surgeons performing distinct parts of a procedure
Modifier 66	Surgical team — for multiple specialized providers on a highly complex procedure

Assistant surgeon billability (CMS NPFS indicator rules)

Determination basisAssistant surgeon billability is determined by the CMS National Physician Fee Schedule 'Assistant Surgeon' indicator values (0,1,2,9)

Indicator values that allow paymentIndicator 2 — Assistant at surgery may be paid; Indicator 0 — may be paid only when supporting documentation of medical necessity and specific services rendered is submitted

Indicator value disallowing paymentIndicator 1 — Statutory payment restriction; assistant at surgery may not be paid

Non‑applicable indicatorIndicator 9 — Concept does not apply

Claim coding requirementNon‑physician assistant must report the same procedure code as the primary surgeon appended with Modifier AS (or the surgery‑only code if the primary billed a global code)

Claim Submission and Documentation Requirements

Billing Rule

Claim submission and billing rules

Submit Modifier AS on CMS-1500 or 837P claims when a physician assistant, nurse practitioner, or clinical nurse specialist assists at surgery. Include the assisting provider's own National Provider Identifier (NPI) on the claim. Do not append modifier AS when the assistant is acting only as an extra set of hands; the assistant must actively assist and participate in the actual performance of the procedure. 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.

Include assisting provider's NPI on all non-physician assistant-at-surgery claims
Do not bill Modifier AS with 80, 81, or 82 on same claim/date/provider
If multiple non-physician providers are required for a complex procedure, bill as a surgical team with Modifier 66 and document each provider's role

Documentation Required

Supporting documentation required for Indicator 0 procedures

When the CMS National Physician Fee Schedule shows an Assistant Surgeon Indicator of 0 for the primary procedure, supporting documentation must accompany the claim to establish medical necessity for an assistant-at-surgery and to identify the specific services the non-physician assistant rendered. The operative report must document the reason the non-physician assistant's services were needed and describe the specific actions performed (not merely that the assistant was present). Failure to submit adequate documentation for Indicator 0 procedures may result in nonpayment.

Documentation must explain why an assistant was necessary and detail the specific services rendered by the non-physician assistant
Include operative report and any additional clinical notes that support medical necessity for the assistant-at-surgery
If the primary surgeon bills a global code, the non-physician assistant should report only the specific surgery-only code appended with modifier AS

Definitions and CMS Indicator

Non‑physician assistant‑at‑surgery — definitions and payment

Physician Assistant (PA)Non‑physician practitioner who may assist in surgery, reports services with own NPI, capable of taking over the surgery if the primary surgeon is incapacitated

Nurse Practitioner (NP)Advanced practice practitioner who may assist in surgery and must report services using own provider NPI

Clinical Nurse Specialist (CNS)Advanced practice practitioner used to report non‑physician assistant‑at‑surgery services and reports using own NPI

Reimbursement rateStandard: 10% of the provider's applicable fee schedule allowed amount for the primary surgery (Alaska: 13%)

CMS Assistant Surgeon indicator — values and implications

Indicator 0Payment restriction applies unless supporting documentation of medical necessity and the specific services rendered by the assistant are submitted with the claim

Indicator 1Statutory payment restriction — assistant at surgery may not be paid

Indicator 2Payment restriction does not apply — assistant at surgery may be paid

Indicator 9Concept does not apply to the procedure