Modifier 82 is appended to a surgical CPT code to indicate that an attending physician acted as an assistant because a qualified resident surgeon was unavailable. In teaching hospitals it documents that no qualified resident was available to assist, that the primary surgeon’s policy precludes resident involvement, or that exceptional medical circumstances required attending assistance (AAPC). CMS requires documentation explicitly stating resident unavailability and, when Medicare allows assistant-at-surgery payment (assistant indicator = allowed), reimbursement for an assistant with modifier 82 is paid at 16% of the Medicare Physician Fee Schedule (MPFS) allowable amount (Noridian Medicare). Commercial payer treatment varies; some plans may reimburse at different percentages (for example, Neighborhood Health Plan of Rhode Island advises ~20% for modifier 80/82) and may have additional documentation requirements.

When billing, append -82 to the assistant surgeon line and include clear documentation that no qualified resident was available; some payers may require a standing policy or an affidavit from the attending surgeon confirming resident unavailability (AAPC, Noridian Medicare). Modifier 82 is intended for teaching hospitals—if a hospital has no residency program, modifier 82 is not required and modifier 80 is typically used without the special resident‑availability statement. Always verify the Medicare assistant‑at‑surgery indicator in MPFS resources to confirm whether assistant payment is permitted for the procedure code in question.

Real‑world examples include: CPT 55866‑82 for a laparoscopic prostatectomy in a teaching hospital when a resident was not available (assistant paid at 16% of MPFS if allowed by Medicare), and CPT 27279‑82 for a minimally invasive sacroiliac joint fusion where a commercial payer may reimburse the assistant at a different percentage (example payer policy indicates ~20%). These examples illustrate the billing line, required documentation, and payer variability in reimbursement.

Because payer policies differ, confirm commercial carrier rules and any required supporting statements before submitting claims. This overview is based on CMS guidance and AAPC coding resources; do not assume reimbursement or documentation rules beyond what those sources specify.