Medically Unlikely Edits (MUEs)

Yes, if you have identified a clerical error and the correct number of units is less than the Medically Unlikely Edit (MUE) value, the claim can be reopened. The claim will not be reopened if the number of units is above the MUE.

CMS reminds providers, other than ambulatory surgical centers, to report bilateral surgical procedures on a single claim line with CPT® modifier -50 and one unit of service. In these cases, a reopening can be requested to change the units of service and add the CPT® modifier -50 when appropriate.

Resources

• Change Request 8853 (PDF): Revised Modification to the Medically Unlikely Edit (MUE) Program 
• CMS Medically Unlikely Edits web page: Practitioner Services MUE Table

Last Reviewed: 03/19/2025

MUEs for HCPCS codes with a MAI of "2" are absolute date of service edits. These are "per day edits based on policy." HCPCS codes with an MAI of "2" have been rigorously reviewed and vetted within CMS and obtain this MAI designation because units of service on the same date of service in excess of the MUE value would be considered impossible because it was contrary to statute, regulation, or sub-regulatory guidance. Units of services billed in excess of the MUE value are considered billing errors. MACs cannot pay units of service billed in excess of a MUE value with a MAI of "2" on an initial claim determination or on a redetermination.

MUEs for HCPCS codes with a MAI of "3" are "per day edits based on clinical benchmarks." MAI 3 indicates it is unlikely additional units of service would appear on a correctly coded claim but could, under unusual circumstances, be payable. If claim denials based on these edits are appealed, MACs may pay UOS in excess of the MUE value if there is adequate documentation of medical necessity of correctly reported units.

Resources

• Change Request 8853 (PDF): Revised Modification to the Medically Unlikely Edit (MUE) Program 
• CMS Medically Unlikely Edits web page: Practitioner Services MUE Table

Last Reviewed: 03/19/2025

CMS publishes most, but not all, of the MUE edit values in a table on the CMS website. You can access the CMS Medically Unlikely Edits page from the link below. Once on that page, scroll the page down and choose Practitioner Services MUE Table. MUE values not published by CMS on this table remain confidential and cannot be released by Medicare contractors.

You can also use the Palmetto GBA Medically Unlikely Edits Lookup Tool to look up published MUE values. Simply enter a CPT® or HCPCS code and choose the appropriate quarterly effective date to find the associated MUE value with the MUE Adjudication Indicator, Rationale, and Source for each MUE.

Resource: CMS Medicare NCCI Medically Unlikely Edits (MUEs) web page: Practitioner Services MUE Table

Last Reviewed: 03/19/2025