When to Use Medicare XE, XP, XS & XU Modifiers

Effective January 1, 2015, CMS will officially roll out four new HCPCS modifiers, XE, XP XS and XU, that can be used when billing Medicare claims. Dubbed the –X{EPSU} subset, they may or may not be used instead of modifier 59.

Not very clear, right? Unfortunately, there hasn’t been much clarification from CMS about the modifiers either, leaving many physicians and medical practices confused.

So today, I’ll focus on a few examples of when you might use each of these new modifiers. And if you need more background information about why this code subset was created in the first place, this post explains that in detail.

But first, a review of the definitions.

  • Modifier XE Separate encounter – A service that is distinct because it occurred during a separate encounter.
  • Modifier XP Separate practitioner – A service that is distinct because it was performed by a different practitioner.
  • Modifier XS Separate structure – A service that is distinct because it was performed on a separate organ/structure.
  • 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.

When to Use Modifiers XE, XP, XS, XU

The following are potential scenarios is which the new Medicare modifiers might be used.


Scenarios Modifier Reasoning & Notes
Surgery operative sessions: One surgery procedure at 9AM and one at 6PM.Physical therapy sessions: Group therapy services (97150) at 10AM and therapeutic exercises (97110) at 4PM.  XE
  • Separate encounters.
  • Same date of service.


Patient is seen by her OB-GYN. During the exam, the doctor notes an issue and requests his partner, a Perinatologist, examine the patient as well.Patient is under treatment for breast cancer. During her appointment, she is seen by two physicians in the practice – the Medical Oncologist and the Radiation Oncologist. XP
  • Separate practitioners.
  • Same date of service.
  • May or may not be the same encounter.
  • May or may not be different specialties.
  • Both practitioners fall under same TIN.


Injection into tendon sheath, elbow (20550) and injection into tendon sheath, knee (20550-XS). XS
  • Separate structure or organ.
  • Different anatomical site.
  • Same encounter.
A diagnostic procedure is performed. Based on the findings, a therapeutic and/or surgical procedure is required on the same day.For example, diagnostic cardiac catheterization is followed by a medically necessary cardiac procedure. XU
  • Same encounter.
  • Same practitioner.
  • Same anatomical site, structure, or organ.


Remember that you’ll never use modifier 59 in conjunction with one of the X{EPSU} modifiers. They are designed to be used separately – it’s either one or the other.

Which, of course, makes this all the more confusing. Watch for CMS to provide further clarification and examples in 2015. And don’t be surprised when other payers begin requiring the more specific modifiers too, since they usually follow CMS’ lead.

Additional Resources

Medicare Learning Network: MLM MM8863

Manual System: Transmittal 1422

Also checkout my other post on these X{EPSU} modifiers.

Source: http://www.capturebilling.com/medicare-modifiers-xe-xp-xs-xu-examples/#axzz3OZIgDRMW