Practice Management: Medicare Coding Changes for 2015: Modifier 59

The new year brings a significant change in how medical practices must code procedures. For 2015, the Centers for Medicare and Medicaid Services (CMS) has established four new Healthcare Common Procedure Coding System (HCPCS) modifiers that define subsets of modifier 59 (distinct procedural service).

Currently, providers use modifier 59 to indicate that a procedure code represents a service that is separate and distinct from another service that the code would usually be bundled with. CMS believes that because modifier 59 is defined for use in a wide variety of circumstances, such as different encounters, different anatomic sites, and distinct services, this newly created subset of modifiers will provide more precise coding when circumstances requiring modifier 59 are present.

The subset modifiers should also help to eliminate incorrect usage of modifier 59 and resulting incorrect payment. Following are the new modifiers:

  • XE (separate encounter): Service occurred during a separate encounter
  • XS (separate structure): Service was performed on a separate organ/structure
  • XP (separate practitioner): Service was performed by a different practitioner
  • XU (unusual nonoverlapping service): Service does not overlap usual components of the main service

These modifiers that define the subsets of modifier 59 are referred to as X{EPSU} modifiers. CMS initially will continue to recognize modifier 59 but gradually will require one of the subset modifiers rather than modifier 59 when certain code pairs are reported. For example, CMS may specify that a particular NCCI code pair is payable only with the XE (separate encounter) modifier but not with modifier 59 or other X{EPSU} modifiers.

For more information on this change, please refer to CMS Manual System, Transmittal 1422, Date: August 15, 2014, Change Request 8863, or MLN Matters Number: MM8863, Related Change Request (CR) 8863, Related CR Transmittal R1422OTN.

The implementation date for this change was January 5, 2015.

To stay up to date on coding changes and initiatives, please visit: Questions and comments may be emailed to ACOG’s Coding Staff at

With the implementation of ICD-10 this fall, this is a great time for you and your staff to attend an upcoming coding workshop.  

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