Medicare X{EPSU} Modifiers Further Define Modifier 59

Modifier 59, the "distinct procedural service" indicator, is problematic because it applies to a wide variety of circumstances. The Centers for Medicare & Medicaid Services (CMS) created four additional modifiers to define subsets of the commonly – but often mistakenly – used indicator.

Properly used according to Medicare National Correct Coding Initiative (NCCI) rules, modifier 59 indicates that a code represents a service separate and distinct from another service with which it would usually be considered bundled. Modifier 59 can identify: 

  • A separate encounter (this usage is infrequent and usually correct, according to CMS);
  • A separate anatomic site (usage less common and less correctly applied); or
  • A distinct service (used commonly and often incorrectly, frequently overriding the NCCI edit in the exact circumstance for which CMS created the edit in the first place). 

The "submodifiers," collectively called X{EPSU} modifiers, define these specific subsets of modifier 59:

  • XE Separate Encounter: a service that is distinct because it occurred during a separate encounter;
  • XS Separate Structure: a service that is distinct because it was performed on a separate organ/structure;
  • XP Separate Practitioner: a service that is distinct because it was performed by a different practitioner; and
  • XU Unusual Non-Overlapping Service: the use of a service that is distinct because it does not overlap usual components of the main service.

CMS says these modifiers "may be utilized in lieu of modifier 59 whenever possible. (Modifier 59 should only be utilized if no other more specific modifier is appropriate.)"

For more information about modifier 59 and the X{EPSU} modifiers, see:

If you are not familiar with the NCCI edits:

If you have questions about billing and coding or payer policies, TMA’s reimbursement specialists can help. Email questions to paymentadvocacy[at]texmed[dot]org, or call the TMA Knowledge Center at (800) 880-7955. Or turn to TMA Practice Consulting for an in-depth review of your documentation and claims coding that could identify deficiencies and areas of risk for an audit. Contact a consultant at (800) 523-8776 or practice.consulting[at]texmed[dot]org.

Revised May 24, 2019

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Last Updated On

May 24, 2019

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