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ED Coding and Reimbursement Alert

Reader Questions:

Get the 411 on MUE

Published on Wed Sep 11, 2024

Question: Could you please clarify what “MUE” means and explain how it impacts my coding?

Indiana Subscriber

Answer: MUE is an acronym for medically unlikely edits, which the Centers for Medicare & Medicaid Services (CMS) established as a unit-of-service edit for HCPCS Level II and CPT® codes. An MUE is assigned to a specific code to represent the maximum number of units of the code that you should report — either on a specific claim or on a specific date.

CMS developed the edits to reduce the paid claims error rate for Medicare claims.

Exceptions: When a provider legitimately exceeds the MUE frequency limit, Medicare has provided guidance for how to override an MUE value, using “distinct service” modifiers, such as 59 (Distinct procedural service) or the following X{EPSU} modifiers:

  • XE (Separate encounter, a service that is distinct because it occurred during a separate encounter): Use this if the provider performs bundled procedures during separate encounters on the same date of service.
  • XS (Separate structure, a service that is distinct because it was performed on a separate organ/structure): If the provider performs bundled services on distinct anatomic sites or possibly on distinctly different sections of one anatomic site, this modifier is a more specific choice than 59.
  • XP (Separate practitioner, a service that is distinct because it was performed by a different practitioner)
  • XU (Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service)

Alert: The MUE table includes a column for “MUE Adjudication Indicator” (MAI), which provides guidance about what circumstances allow you to override an MUE limit for a given code. If the code has an MAI of “1,” the code is adjudicated on a claim-line basis, meaning that you can’t exceed the number of MUE units on a claim line. You are allowed to use one of the distinct-service modifiers to override the edit if circumstances allow.

An MAI of “2” means that the frequency limit is absolute for a date of service, and you may not override the edit with a modifier.

An MAI of “3” means that the frequency limit is based on the date of service, and Medicare will automatically deny any claims in excess of that limit, even if you use an appropriate modifier. However, Medicare will consider an appeal with appropriate documentation.

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