New Subset Added to Modifier 59

 In Articles, Coding & Documentation, Policy Updates


MSOC Health is providing this summary to keep you abreast of the upcoming changes to modifier 59. At this point in time, neither CMS nor our local MAC (Palmetto) has provided a list of “must-use” CPT combinations. Our recommendation is to share this information with providers and staff in your practice, verify that your EMR has these new modifiers as options from when entering a billing code, and update encounter forms if appropriate. Providers may want to consider using the X modifiers in place of the 59 modifier starting with dates of service in January as payers will accept these more specific codes ahead of instruction from CMS.


The Centers for Medicare and Medicaid Services (CMS) has established four new HCPCS modifiers to define subsets of modifier 59 – the modifier used to define a “Distinct Procedural Service” – effective for dates of service beginning January 1, 2015 on Medicare claims. Currently, providers use modifier 59 to indicate that a CPT code represents a service that is separate and distinct from another service in which it would usually be considered to be bundled. Since modifier 59 is so broadly applied, CMS is concerned that providers may be using it incorrectly to bypass National Correct Coding Initiative (NCCI) edits that are in place to prevent unbundling of services and the consequent overpayment to physicians and outpatient facilities. According to CMS, “This modifier is associated with considerable abuse and high levels of manual audit activity; leading to reviews, appeals and even civil fraud and abuse cases.”

There are instances when it would be accurate to report modifier 59 to let CMS know that payment for both procedures is justified, but CMS believes this would occur less frequently than the reporting of modifier 59 would suggest. CMS presumes that modifier 59 is commonly used and abused. The primary issue associated with this modifier is that it is defined for use in a wide variety of circumstances. It can be used to identify:

  • Different encounters;
  • Different anatomic sites; and
  • Distinct services.

The 59 modifier is:

  • Infrequently (and usually correctly) used to identify a separate encounter;
  • Less commonly (and less correctly) used to define a separate anatomic site; and
  • More commonly (and frequently incorrectly) used to define a distinct service.

Modifier 59 often overrides the edit in the exact circumstance for which CMS created it in the first place. CMS believes that more precise coding options coupled with increased education and selective editing is needed and may help reduce the errors it’s seeing and the associated overpayment.

CR8863 provides information that CMS is establishing the following four new HCPCS modifiers (referred to collectively as X{EPSU} modifiers) to define specific subsets of the 59 modifier:

  • 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 will continue to recognize the 59 modifier in many instances, but may selectively require a more specific X{EPSU} modifier for billing certain codes at high risk for incorrect billing. For example, a particular NCCI code pair may be identified as payable only with the XE separate encounter modifier but not the 59 or other X{EPSU} modifiers. The X{EPSU} modifiers are more selective versions of the 59 modifier, so it would be incorrect to include both modifiers on the same line.

The combination of alternative specific modifiers with a general less specific modifier creates additional discrimination in both reporting and editing. As a default, at this time CMS will initially accept either a 59 modifier or a more selective X{EPSU} modifier as correct coding, although the rapid migration of providers to the more selective modifiers is encouraged. Medicare contractors may choose to require reporting of the more specific modifiers. The modifiers are valid modifiers even before national edits are in place, so contractors are not prohibited from requiring the use of selective modifiers in lieu of the general 59 modifier when necessitated by local program integrity and compliance needs.

CMS has provided these additional requirements to the MACs:

  • Contractors shall accept and process claims containing lines reporting HCPCS codes with the new modifiers: XE, XP, XS and XU.
  • Contractors shall apply or bypass edits to lines containing a X{EPSU} modifier in the same manner as the edits would apply to a line containing a 59 modifier. Any edit that currently evaluates modifiers, such as a multiple procedure edit, should react to a X{EPSU} in the same manner that it does to a 59.
  • Contractors shall recognize each of the X{EPSU} modifiers as a separate modifier. The system shall allow multiple lines to be reported with the 59 and different X{EPSU} modifiers. However, the system shall aggregate lines with any of the X{EPSU} modifiers with lines containing 59 modifiers whenever it aggregates lines containing the 59 modifier.

Be on the lookout for additional communication from CMS and Palmetto GBA or your MAC on further defining required modifier usage. As noted in the change request, contractors or CMS may selectively require the use of the X modifiers in the future to address high risk billing patterns. At this time, minimal information has been published on these modifiers, but expect more to come in the future.

CMS – MLN Matters: Specific Modifiers for Distinct Procedural Services

CMS Manual System – Pub 100-20 One-Time Notification

For additional help with coding at your practice, contact Amy Dunatov at or 919.442.1100.

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