CMS Pub. 100-04, ch. 12, § 20.4.3

For assistant-at-surgery services performed by physicians, the fee schedule amount equals 16

percent of the amount otherwise applicable for the surgical payment.

A/B MACs (B) may not pay assistants-at-surgery for surgical procedures in which a physician

is used as an assistant-at-surgery in fewer than five percent of the cases for that procedure

nationally. This is determined through manual reviews.

Procedures billed with the assistant-at-surgery physician modifiers -80, -81, -82, or the AS

modifier for physician assistants, nurse practitioners and clinical nurse specialists, are subject

to the assistant-at-surgery policy. Accordingly, pay claims for procedures with these modifiers

only if the services of an assistant-at-surgery are authorized.

Medicare’s policies on billing patients in excess of the Medicare allowed amount apply to

assistant-at-surgery services. Physicians who knowingly and willfully violate this prohibition

and bill a beneficiary for an assistant-at-surgery service for these procedures may be subject to

the penalties contained under §1842(j)(2) of the Social Security Act (the Act.) Penalties vary

based on the frequency and seriousness of the violation. Go to

http://www.ssa.gov/OP_Home/ssact/title18/1800.htm and select the relevant section.