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Denials due to MUE Usage - This May be Why!

Christine Woolstenhulme, QMC QCC CMCS CPC CMRS

National Correct Coding Initiative (NCCI) Medically Unlikely Edits (MUEs) are used by the Medicare Administrative Contractors (MACs) to reduce improper payments for Part B claims.

CMS assigns Medically Unlikely Edits (MUEs) for HCPCS/CPT codes, although not every code has an MUE. MUE edits are used to limit tests and treatments provided to a Medicare patient for a single date of service or for a single line item on a claim form. It is important to understand that MUEs are not to be used as utilization guidelines. CMS states, "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 only to report services that are medically reasonable and necessary." 

Although CMS publishes most MUE values on its website, other MUE values are confidential.  Confidential MUE values are not releasable. This is discussed in this article. 

Find-A-Code lists the MUE values that have been released by CMS; these MUEs can be found on the CPT code information page under the additional information for easy access. 

What are the MAI indicators?

Each MUE is assigned a Medicare Adjudication Indicator (MAI), further specifying how MACS look at MUEs. MUEs and MAIs are used by providers, suppliers, and MACS in all settings.  These are the most common and published MAIs. There are MUEs with a value of less than 1 and a value of 4 or more that are not published due to concerns from CMS about fraud and abuse.

MAI 1 -  adjudicated as a claim line edit 
MAI 2 -  per day edits based on policy (Impossible to bill excess MUEs)
MAI 3 -  per day edits based on clinical benchmarks (UOS in excess of the MUE value were actually provided, were correctly coded, and were medically necessary)

MUEs are automatically denied or deemed an "auto-deny edit"

Because they are auto-deny edits, it is important to be aware of the MAIs assigned to each MUE. These types of denials should all be appealed and sent back for reconsideration if denied incorrectly.  ASC Providers (specialty Code 49) cannot use modifier 50 (Bilateral procedure); therefore, the MUE with an MAI of 1 is automatically doubled by the MAC.

Incorrect usage of MUEs will be denied as a coding denial, not a clinical or medically necessary denial. 

Claim Remark Codes 

On your EOB or remittance advice, to identify claims that fail the MUE edit claim, remark codes N362 and MA01 will be used.   


Inquiries about the MUE program, including those related to NCCI (PTP, MUE, and Add-On) edits, should be sent to NCCIPTPMUE@cms.hhs.gov. Inquiries about a specific claim should be addressed to the appropriate MAC.

Appeals and Reconsideration

If a national healthcare organization, provider, or other party wants to submit a request for reconsideration of an MUE value, the procedure described in the Frequently Asked Questions (FAQs) should be followed.  See the web link below.  Such requests should be addressed to:

National Correct Coding Initiative
Email: NCCIPTPMUE@cms.hhs.gov
P.O. Box 368
Pittsboro, IN 46167

Fax #:  317-571-1745