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What exactly are Medically Unlikely Edits (MUE)?

 "A MUE is a maximum number of Units of Service (UOS) allowable under most circumstances for a single Healthcare Common Procedure Coding System/Current Procedural Terminology (HCPCS/CPT) code billed by a provider on a date of service for a single beneficiary." That is, MUEs place limits on the number of units of service per CPT code that can be reported by a provider for the same patient on the same date of service. Items billed above the established number of units allowed in one day are automatically denied as a “Medically Unlikely Edit". 

The Centers for Medicare and Medicaid Services (CMS) developed the Medically Unlikely Edit (MUE) program to reduce the paid claims error rate for Part B claims. The first edits were implemented on January 1, 2007. Subsequently there have been quarterly updates increasing the number of edits. MUE tables can be found on the CMS website.(1)  

Most MUEs are visible to providers on the website. However, some MUEs are considered confidential by CMS and are not released. CMS will not publish all MUE values that are 4 or higher because of its concerns about fraud and abuse. National healthcare organizations and contractors with information about MUE values that are not published on the CMS website should continue to maintain confidentiality of those values. In addition, a minimal number of MUEs with lower values that are believed by CMS to be particularly vulnerable to fraud and abuse may not be published. CMS is concerned that providers will incorrectly interpret MUE values as utilization guidelines. MUE values do NOT represent units of service that may be reported without concern about medical review. Providers should continue to only report services that are medically reasonable and necessary.(2)


Review these important points:

If you report a HCPCS/CPT code with units greater than the MUE value assigned, the line and/or claim will be denied

Be aware of the description of a HCPCS/CPT code when billing a service, for instance:

  • Initial evaluation and management (E/M)
  • Subsequent E/M

Many HCPCS/CPT codes have common or similar terms, but there are differences in the description. Some examples include:

  • Bilateral
  • Unilateral
  • Greater than
  • Less than
  • With
  • Without
  • Or

MUEs do not exist for all HCPCS/CPT codes:

  • When requested, records should explain why the patient required more than the approved MUE for any service
  • Documentation submitted must support the units of service billed as reasonable and necessary
  • When billing, append the appropriate modifiers
  • While the majority of MUEs are publicly available on the CMS website, CMS will not publish all MUE values because of fraud and abuse concerns (1)


Denied as Medically Unlikely (MUE)

  • If your service was denied based on a Medically Unlikely Edit (MUE), that means that the number of services you billed is more than the number allowed in one day.
  • Services denied because of an MUE are considered a coding error. You cannot bill your patient.


How do I correct a claim that was rejected for Medically Unlikely Edits (MUEs)?


  • Providers can adjust a claim that rejected for MUE edits by lowering the number of units billed. Adjustments must be sent in hardcopy with condition code D9 and the following remark on the second line of the remarks section on the claim verbatim: Units.
  • If the units are correct, the provider will need to submit an appeal with documentation to support the medical necessity.

I billed multiple units of a procedure code, and my claim was initially denied. I appealed the denial, but only some of the units were reprocessed. Did Medicare forget to reprocess some of the units of my service?


  • It is important to review the response that Medicare's Redeterminations staff would have sent you when they completed their review. It is likely the response said the outcome of your appeal was partially favorable. In most cases like this, the procedure code in question is subject to a Medically Unlikely Edit (MUE), which is the maximum units of service that a provider would report under most circumstances for a single beneficiary on a single date of service. 
  • Unless the documentation submitted with the appeal supports the billing of more units than the MUE allows, Medicare would only allow up to the maximum MUE value. For example, if the MUE value for your code is 6 units, and you billed 8 units, Medicare would usually allow only 6 units and deny the other 2 units.(1)

Wound Care Example: 

  • 11042 Debridement, subcutaneous tissue (includes epidermis and dermis, if performed); first 20 sq cm or less
  • 11045 Debridement, subcutaneous tissue (includes epidermis and dermis, if performed); each additional 20 sq cm, or part thereof (List separately in addition to code for primary procedure)

The MUE for 11042 is 1 per day, which is the maximum units of service that a provider would report under most circumstances for a single beneficiary on a single date of service. If the sqcm exceeded 20, the provider should apply the add-on code 11045. The MUE per day for 11045 is 12. 




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