Modifiers · CPT modifier

Assistant surgeon

Modifier 80 flags a claim when a physician acts as a second surgeon during an operation—actively lending hands-on assistance to the primary surgeon rather than performing a separate procedure. It is routinely used in complex orthopedic cases such as total joint replacement, spinal fusion, and high-energy fracture fixation where a single surgeon cannot safely manage the operative field alone.

Verified May 8, 2026 · 10 sources ↓

Type: CPT
CPT codes use it: 1,007
Top regions: Other, Foot & ankle, Spine

Drawn from AMACMSNovitasModahealthPremera

When to use modifier 80

Source · Editorial brief grounded in 10 cited references ↓

Append modifier 80 to the same CPT procedure code(s) billed by the primary surgeon whenever a second physician actively participates in performing those procedures. The assistant surgeon does not get a unique code—the codes mirror the primary surgeon's claim, with modifier 80 added. For example, in a bilateral TKA (CPT 27447 x2) requiring retraction and component alignment support, the assisting physician bills 27447-80 for each side. Medicare reimburses the assistant at roughly 16% of the primary surgeon's allowable fee; multiple-procedure and bilateral reductions still apply to that reduced base.

Modifier 80 is appropriate in both community hospitals and teaching facilities. In a teaching hospital, use modifier 82 instead when the reason a physician assistant surgeon was needed is specifically because no qualified resident was available. Do not default to 80 when 82 is the correct signal—payers audit this distinction. In non-teaching facilities, modifier 80 is the standard choice and modifier 82 does not apply.

Non-physician providers—PAs, NPs, and CNSs—must use modifier AS, not modifier 80. Mixing 80 and AS on the same claim, same date, same provider is an automatic billing error. The assistant's identity and specific intraoperative tasks must appear in the operative note; simply listing the assistant's name in the header is insufficient documentation.

Orthopedic scenarios

Concrete situations in orthopedic practice that warrant modifier 80.

Source · Editorial brief grounded in AAOS coding guidance and cited references ↓

Primary total knee arthroplasty (CPT 27447): assistant physician bills 27447-80; operative note documents the assistant's role in tibial exposure, retractor placement, and trial component seating during a complex case involving severe valgus deformity.
Posterior spinal fusion with instrumentation (CPT 22612 + 22614): assistant bills each segment code with modifier 80 appended; note specifies assistant maintained retraction of the thecal sac and handed implants during pedicle-screw placement.
Open reduction and internal fixation of a distal femur fracture (CPT 27513): assistant bills 27513-80; operative note states the assistant reduced the condylar fragment and held provisional K-wire fixation while the primary surgeon applied the lateral locking plate.
Revision total hip arthroplasty with acetabular component removal (CPT 27134): assistant bills 27134-80; documentation details the assistant's management of the femoral canal and cement removal while the primary surgeon addressed acetabular bone loss.
Tibial plateau ORIF (CPT 27535 or 27536 depending on fracture pattern): assistant bills with modifier 80; note records assistant's sustained limb traction and maintenance of reduction during lag-screw and buttress-plate application.
Simultaneous bilateral total knee arthroplasty (CPT 27447-50 or 27447 x2): assistant bills the bilateral codes with modifier 80 on each; payer applies bilateral reduction to the primary allowable first, then calculates the 16% assistant rate from that reduced amount.

Common mistakes

Where coders most often go wrong with modifier 80.

Source · Editorial brief grounded in CMS NCCI Policy Manual and cited references ↓

Appending modifier 80 for a PA or NP assistant instead of modifier AS, which triggers a denial because payers map 80 exclusively to physician providers.
Billing a different CPT code than the primary surgeon—the assistant's claim must mirror the primary surgeon's procedure codes; an exception exists only when the primary bills a global OB maternity code, in which case the assistant bills the delivery-only code.
Using modifier 80 in a teaching hospital when no qualified resident was available; that scenario requires modifier 82, and substituting 80 omits a legally required certification statement.
Documenting the assistant's involvement only in the case header (e.g., 'Assisted by Dr. X') without describing specific tasks such as femoral canal reaming, retraction of neurovascular structures, or wound closure—payers treat vague headers as no documentation.
Stacking modifier 80 with co-surgeon modifier 62 or team surgery modifier 66 on the same procedure code; those modifiers are mutually exclusive with 80 because they describe different surgeon relationships.
Failing to check the CMS Assistant Surgeon Payment Policy Indicator before billing—codes with indicator '1' are statutorily excluded from assistant surgeon reimbursement regardless of clinical necessity.
Submitting modifier 80 claims without following the payer's unsolicited paperwork (PWK) process when the procedure carries a payment indicator of '0', causing automatic denial rather than medical-necessity review.

CPT codes that use modifier 80

1,007 orthopedic CPT codes in our reference list this modifier as applicable. Sorted by total RVU.

Source · Derived from per-code modifier guidance in our CPT reference

Showing top 12 of 1,007 by total RVU.

Where modifier 80 shows up

Body regions where this modifier most commonly appears in our orthopedic reference.

Other 174 codes
Foot & ankle 145 codes
Spine 127 codes
Wrist 108 codes

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 10 cited references ↓

01How much does Medicare pay an assistant surgeon billing modifier 80?

Medicare reimburses approximately 16% of the primary surgeon's Medicare allowable for the same procedure. Multiple-procedure and bilateral-procedure reductions apply to that base allowable before the 16% rate is calculated, so the effective dollar amount can be lower than 16% of the full fee schedule rate.

02Can a PA or NP assistant use modifier 80?

No. Non-physician providers—PAs, NPs, and CNSs—must append modifier AS to indicate assistant-at-surgery services. Modifier 80 is reserved for physician (MD or DO) assistants. Billing 80 for a PA or NP will result in a denial; Medicare also pays AS at a further reduced rate, roughly 85% of the physician assistant surgeon allowable.

03Does the assistant surgeon need to write a separate operative note?

The assistant surgeon does not need to dictate a separate operative report. However, the primary surgeon's operative note must describe specifically what the assistant did—such as maintaining retraction during ORIF or assisting with implant trialing during TKA. A bare listing of the assistant's name is not sufficient documentation for payment.

04What is the difference between modifier 80 and modifier 82?

Modifier 80 is the general assistant-surgeon modifier used when a physician assists in any surgical setting. Modifier 82 is restricted to teaching hospitals and is used only when no qualified resident was available to assist; that circumstance must be documented in the medical record and requires a specific physician attestation.

05Can modifier 80 be billed alongside modifier 62 or 66?

No. Modifiers 62 (co-surgeons) and 66 (surgical team) describe fundamentally different operative arrangements than an assistant surgeon. Appending modifier 80 to a code already billed with modifier 62 or 66 is a billing error and will be denied. Choose the modifier that accurately reflects the actual surgical arrangement.

06Which CPT codes are eligible for assistant surgeon billing?

Eligibility is determined by the CMS National Physician Fee Schedule 'Assistant Surgeon' payment policy indicator. Indicator '2' means the assistant can be paid without restriction; indicator '0' means documentation of medical necessity must be submitted; indicator '1' means the code is statutorily excluded from assistant surgeon reimbursement. Always verify the indicator before billing.

07Does modifier 80 affect the primary surgeon's reimbursement?

No. The primary surgeon bills without any modifier for their role and is paid the full allowable. The assistant surgeon's modifier 80 claim is adjudicated separately and does not reduce or alter the primary surgeon's payment.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

01AMA CPT Professional Edition – Modifier 80 descriptor and assistant-at-surgery guidelines
02CMS NCCI Policy Manual – Chapter on correct coding and payment indicators for assistant surgeons
03
novitas-solutions.com
https://www.novitas-solutions.com/webcenter/portal/MedicareJL/pagebyid?contentId=00144529
04
modahealth.com
https://www.modahealth.com/-/media/modahealth/shared/Provider/Policies/RPM013-Modifiers-80-81-82-AS-Assistant-at-Surgery.pdf
05
premera.com
https://www.premera.com/paymentpolicies/cmi_051730.pdf
06
kzanow.com
https://www.kzanow.com/coding-coaches/reimbursement-assistant-surgeon-ortho
07
aapc.com
https://www.aapc.com/codes/coding-newsletters/my-orthopedic-coding-alert/modifier-of-the-month-modifiers-80-and-82-aid-assistant-surgeon-claims-article
08
aapc.com
https://www.aapc.com/codes/coding-newsletters/my-general-surgery-coding-alert/modifiers-understand-how-to-apply-assistant-at-surgery-modifiers-177296-article
09
cms.gov
https://www.cms.gov/Regulations-and-Guidance/Guidance/Transmittals/downloads/R1620CP.pdf
10
cms.gov
https://www.cms.gov/medicare/coding-billing/national-correct-coding-initiative-ncci-edits/medicare-ncci-faq-library

Mira AI Scribe

When documenting a case where a second physician assisted at surgery, the operative note must go beyond listing an assistant's name. Clearly state what the assistant physically did during the procedure—for example, 'The assistant maintained femoral retraction, provided counter-traction during acetabular reaming, and closed the iliotibial band.' This specificity is required for modifier 80 reimbursement. If the facility is a teaching hospital and no qualified resident was available, document that fact explicitly and use modifier 82 instead of 80. Do not use modifier 80 for PA or NP assistants; those providers require modifier AS. The assistant surgeon bills the identical CPT codes as the primary surgeon, each appended with modifier 80, and is reimbursed at approximately 16% of the primary's Medicare allowable.

See how Mira flags modifier 80 in dictation