Medically Unlikely Edits (MUEs)

Published 04/29/2021

While the majority of MUEs are publicly available on the CMS website, CMS will not publish all MUE values. MUEs that are published, are shown in tables on the CMS website

MUE Tables change quarterly; the date of the change only affects claims with dates of service (DOS) on or after the new updated tables are issued. For example, if an MUE has an allowed amount of two on March 4, 2020, and the updated table shows an increase to five units as of April 1,2020, the allowed for March 4, 2020, is still two. Any claims with date of service on or after April 1, 2020, would have an allowed amount of five.

Some MUEs allowed units are not published in the MUE table; this does not mean that there are no allowed units. It only means that CMS does not publish the allowable units for that code.

CMS MAI Indicators
The MUE Adjudication Indicator (MAI) indicates the type of MUE and its basis. The MAI assigned to HCPCS/CPT codes will determine how your claim will process and/or deny. 

The MAI types are listed in the charts below.

MAI of “1” or 51 MUE

MUEs for HCPCS codes with a MAI of “1” will continue to be adjudicated as a claim line edit

May require modifiers to distinguish: 

Repeat services

Anatomic differences

MAI of “2” or 53 MUE

MUEs for HCPCS codes with a MAI of “2” are absolute date of service edit 

Lines for same date of service are added together for the total number of units billed

No need to split units to separate lines if appealing, the denial is for the total number of units billed

These are “per day edits based on policy”

Based on statue, description of HCPCS/CPT code, or coding guidance

CMS gives no instances in which a higher value would be correct and payable

Expectation is provider will not bill above allowable MUE 

MAI of “3” or 54 MUE

MUEs for HCPCS codes with a MAI of “3” are date of service edits 

These are “per day edits based on clinical benchmarks” 

Lines for same date of service are added together for the total number of units billed

No need to split units to separate lines if appealing, the denial is for the total number of units billed

Appealed additional units are considered if there is adequate documentation of medical necessity to support reported units 

Correct Billing Examples
Biopsy services:

Line 1 = 11100 (MAI 2) Biopsy of single growth of skin and/or tissue — 1 unit

Line 2 = 11101 (MAI 3) Biopsy of each additional growth of skin and/or tissue — each additional unit

Lab services:

Line 1 = 87070 (MAI 1) Bacterial culture — 3 units

Line 2 = 87070 91 (MAI 1) Bacterial culture — 2 units

Surgical services:

Line 1 = 26111 (MAI 3) Excision, tumor or vascular malformation, soft tissue of hand or finger, subcutaneous; 1.5 cm or greater — 4 units

Important Points for Review

If you report a code with units greater than the MUE value assigned, the line and/or claim will deny. 

Be sure to carefully assess the description of a HCPCS/CPT code when billing a service, some important key words examples are noted below:

  • Initial
  • Subsequent
  • Single level
  • Second level

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

Some important reminders include:

  • MUEs do not exist for all HCPCS/CPT codes 
  • When appealing a MUE denial, records should clearly explain why the patient required more than the approved MUE for any service. A statement merely indicating that the patient required additional units, is not acceptable. 
  • Documentation submitted must support the units of service billed as reasonable and necessary
  • Append the appropriate modifiers to ensure proper payment of the claim

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