The 59 modifier should only be used to identify codes that are on the Correct Coding Initiative bundling table, unless specific instructions have been published for additional functions for this modifier. A good example is for multiple anesthesia services on the same day. We published instructions in the Medicare Advisory for use of the 59 modifier on the second anesthesia service. This applies only when a second operative session is involved. We extended this modifier to the Mohs micrographic surgery procedures when a stage is repeated on a different site during the same operative session. The modifier identifies procedures that were performed on a separate site or during a separate operative session. This modifier does not apply to billing the same procedure code during the same session, such as 20550. If the injection is performed on different knees, then the second 20550 is filed with the 51 modifier. This code falls under the multiple surgery rule, so the second procedure is reduced by 50%. If you billed for multiple digits on the hand, then you would use the digit modifiers, not the 59 modifier. Modifier 59 example: Mrs. Smith comes to your office complaining of multiple lesions. You remove five skin tags from the neck (11200) and perform laser surgery to remove 16 lesions on her back (17004). Procedure code 17004 is on the bundling table bundled into 11200. The procedures are on different sites, so the 59 modifier is applicable. You bill code 11200 on one line and 1700459 on the next line .