Medically Unlikely Edits (MUEs)

No, a patient is not liable for a service that was denied for MUE. A denial of services due to an MUE is a coding denial, not a medical necessity denial. Therefore, the presence of an ABN does not shift liability to the beneficiary and ABN issuance based on an MUE is not 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: 12/14/2024

CMS assigns an MUE Adjudication Indicator (MAI) to each HCPCS code that has been assigned an MUE value. All published MUEs are published with their MAI and their MUE rationale.

• An MAI of "1" means the MUE for the HCPCS code is adjudicated as a claim line edit. The edit applies to all units billed on a single claim line.
• An MAI of "2" or "3" means the MUE for the HCPCS code is a date of service edit. Date of service edits apply to all units of service billed for the procedure code for the same date of service, Medicare Number and provider.

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: 12/14/2024

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: 12/14/2024

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: 12/14/2024

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: 12/14/2024

Many bilateral services have a MUE value of 1, and most MUEs are per-day edits. Billing in excess of the MUE value for a date of service will result in denial. This applies to all instances of the procedure code billed for the date of service, whether on a single claim line, on multiple claim lines, or on multiple claims. 

When billing a bilateral procedure with an MUE of 1, follow the billing guidelines for the Medicare Physician Fee Schedule bilateral indicator assigned to the procedure. If the bilateral indicator is 1, and the service was performed bilaterally, all providers (other than Ambulatory Surgical Center providers) must bill a single unit of service on one line using CPT® modifier 50. Claims submitted with two lines or two units and anatomic modifiers will be denied for incorrect coding. 

Refer to the Payment Policy Indicators on the CMS Physician Fee Schedule (PFS) Lookup Tool to determine the bilateral (BILAT) indicator. Access the PFS Lookup Tool directly from the CMS website . 

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: 12/14/2024