HCPCS Modifier XU

Published 07/16/2020

HCPCS Modifier XU — unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service.

Guidelines and Instructions
HCPCS modifier XU indicates that a service is distinct because it does not overlap usual components of the main service. It is used to note an exception to National Correct Coding Initiative (NCCI) edits. It is effective January 1, 2015.

As a subset of HCPCS modifier 59, it is a more selective version of HCPCS modifier 59 and it would be incorrect to include both modifiers on the same line. It is also inappropriate to submit HCPCS modifier XU with evaluation and management codes.

Documentation is required in the patient's medical record to substantiate the use of all modifiers, including HCPCS modifier XU.

  • The purpose of NCCI is to promote correct coding and prevent improper payments
  • NCCI edits bundle component codes into the more inclusive code
  • NCCI edits may be updated as often as quarterly. Most edits are available on the CMS website.
  • More about NCCI edits:
    • Codes are designated as Column I or Column II codes. Most of the time, the "parent" code is in Column I and component code in Column II. For some code pairs, the Column I and II codes are considered "mutually exclusive" and should not be reported together (for example, a vaginal hysterectomy and total abdominal hysterectomy).
    • If both codes from a Column I and II code pair are submitted, the Column I code may be reimbursed and the Column II code will not be reimbursed. Exceptions may apply; in these cases, the Column II code must be submitted with a modifier, and documentation is required in the patient’s medical record.
 Modifier Indicator  Explanation


Codes are always bundled; do not submit a modifier for exceptions.


Exceptions may apply; submit the appropriate modifier. (Note: documentation is required in the patient’s medical record.) 


Not applicable. The code pair is no longer bundled and no modifier is needed for purposes of noting an NCCI exception. 


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