• Modifier 51 and 59 are both used on second and subsequent surgical procedures, when performed on the day of a primary procedure
• See also Modifier 59 quick reference sheet

There are two modifiers commonly used in surgical specialties when billing two or more procedures at the same encounter.  Appending the correct modifier increases the likelihood that the claim will be paid the first time, correctly.

Modifier 51 indicates that a second procedure was performed, and it is not a component code of the first procedure, that is, there is no procedure-to-procedure bundling edit. Medicare contractors do not require modifier 51 on claims. Modifier 51 is not used on add-on codes, which are indicated by a plus sign before the code in the CPT^® book.  Add-on codes are listed in Appendix D in the CPT book.