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December 20, 2021 – Updated January 10, 2022

This article was updated and revised on January 10, 2022 to provide additional information on Advance Beneficiary Notices (ABNs) related to MUEs.

Medically Unlikely Edits (MUEs) & Clinically Unbelievable Edits (CUEs)

Medically Unlikely Edits (MUEs)

The Centers for Medicare and Medicaid Services (CMS) created MUEs to reduce the paid claim error rate for Part B claims. An MUE for a HCPCS code is the maximum units of service that a supplier/provider would bill under most circumstances for a single beneficiary on a single date of service. These edits are set to deny claim lines exceeding the acceptable maximums. MUE denials are identified by ANSI Reason Code 151 with Remark Code MA01 on the remittance advice.

Most MUE values are published by CMS, but some are confidential. Confidential MUEs are for CMS and CMS Contractors' use only. View additional MUE information on the CMS websiteExternal website.

MUE Advance Beneficiary Notice Guidance:

The purpose of the National Correct Coding Initiative MUE program is to prevent improper payments when services are reported with incorrect units of service. ABN issuance based on an MUE is NOT appropriate. A denial of services due to an MUE is a coding denial, not a medical necessity denial. The presence of an ABN shall not shift liability to the beneficiary for units of service denied based on an MUE. Denials resulting from MUEs are not based on any of the statutory provisions that give liability protection to beneficiaries under section 1879 of the Social Security Act. Thus, ABN issuance based on an MUE is NOT appropriate.

If, during reopening or redetermination, medical records are provided with respect to an MUE denial for an edit with an MUE Adjudication Indicator (MAI) of "3," MACs will review the records to determine if the supplier actually furnished units in excess of the MUE, if the codes were used correctly, and whether the services were medically reasonable and necessary. If the units were actually provided but one of the other conditions is not met, a change in denial reason may be warranted (for example, a change from the MUE denial based on incorrect coding to a determination that the item is not reasonable and necessary under section 1862(a)(1)). This may also be true for certain edits with an MAI of "1." CMS interprets the notice delivery requirements under Section 1879 of the Social Security Act as applying to situations in which a supplier expects the initial claim determination to be a reasonable and necessary denial.

ABN & MUEs Summary:

  • An ABN is not appropriate for items billed with incorrect units of service receiving an MUE denial.
  • ABN issuance is only appropriate if the correct units are billed, and suppliers expect a not reasonable and necessary denial, and the beneficiary was properly notified prior to the items being provided. Suppliers must request a redetermination with medical records and the ABN to have the incorrect coding denial (MUE) reconsidered.

Clinically Unbelievable Edits (CUEs)

Clinically Unbelievable Edits (CUEs) are like MUEs but were created by Medicare contractors instead of CMS. CUEs serve the purpose of reducing the paid claim error rate. Providing supplies greater than the utilization parameters outlined in a particular Local Coverage Determination (LCD) and/or Policy Article is often the result of multiple suppliers servicing the same beneficiary. Claims for supplies that exceed clinically unbelievable parameters are automatically denied as not reasonable and necessary. CUE denials are identified by ANSI Reason Code 151 with Remark Code N115, N362, or M25.

Unlike MUE values, all CUE values are confidential.

Suppliers may request a redetermination with medical documentation to support the need for excessive items for denials issued based clinically unbelievable parameters.



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