National Correct Coding Initiative (NCCI)


  • The Centers for Medicare & Medicaid Services (CMS) developed National Correct Coding Initiative (NCCI) edits for claims processing to prevent improper payments to providers when incorrect procedure code combinations and units are submitted.


  • Originally implemented within Medicare in 1996 for claims submitted by physicians.
  • NCCI policies are based on:
    • Coding conventions defined in the American Medical Association's (AMA) Current Procedural Terminology (CPT) Manual
    • National and local Medicare policies and edits
    • Coding guidelines developed by National societies
    • Standard medical and surgical practice

Medically Unlikely Edits (MUEs)

  • Developed by CMS in 2007 to reduce paid claims errors for Medicare claims.
  • MUEs are the maximum units of service that a provider can submit in most circumstances for a client on a single date of service.
  • Edits were developed based on:
    • Anatomic considerations
    • Healthcare Common Procedure Coding System (HCPCS)/CPT code descriptions and instructions
    • Nature of services/procedures
    • Nature of lab material under examination
    • Nature of equipment
  • Providers should continue to report services that are medically reasonable and necessary. MUEs are not intended to be used as utilization guidelines.

General Process

  • Providers submit claims for procedures and services rendered to clients using HCPCS codes.
  • HCPCS codes are submitted via claim form to a fiscal agent for payment.
  • NCCI policies and edits identify claims performed by the same provider for the same client on the same date of service.
  • NCCI edits define pairs of HCPCS/CPT codes that should not be reported together based on criteria of reasons.
  • MUEs are reviewed on claims where the units of service are not likely to be correct. For example, claims for excision of more than one gallbladder or pancreas.

NCCI Methodologies

  • NCCI edits or procedure-to-procedure edits that define pairs of HCPCS/CPT codes that should not be reported together for a variety of reasons, and
  • MUEs or units-of-service edits that define for each HCPCS/CPT code the number of units of service beyond which the reported number of units of service is unlikely to be correct (for example, claims for excision of more than one gallbladder or more than one pancreas).

Quarterly Update

Providers are encouraged to monitor the Centers Medicare & Medicaid Services (CMS) website for updates to NCCI rules and guidelines. The updates for the Procedure To Procedure (PTP) and MUE files are completed quarterly with the next file update available in April 2024. The CMS NCCI website is listed below.

Visit the NCCI for Medicaid web page on the CMS website for more information, including NCCI and MUE edits.