March 2010

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National Correct Coding Initiative Edits

by Melanie Endicott, MBA/HCM, RHIA, CCS, CCS-P

The Centers for Medicare and Medicaid Services (CMS) has developed a list of coding edits an effort to promote correct coding nationwide and to prevent the inappropriate unbundling of related services. The National Correct Coding Initiative (NCCI) edits help CMS detect inappropriate codes submitted on claims that are based on CPT coding guidelines, current standards of medical or surgical coding practice, and advice from specialty societies. There are three major types of coding edits: the comprehensive/component edit, the mutually exclusive edit, and the medical unlikely edit.

Comprehensive/Component Edit

The comprehensive/component edit pertains to HCPCS codes that should not be used together. The following is an example of a NCCI listing:

Comprehensive Code                  Component Code(s)
20912                             12014, 13152

Under the NCCI, if bills contain a procedure in both the comprehensive code column and the component code column for the same patient on the same date of service, only the code in the comprehensive code column is covered (provided that code is on the list as an approved procedure for reimbursement).  

In the preceding example, code 20912 describes a cartilage graft of nasal septum. During the procedure, the surgeon may mention that a wound repair (12014, 13152) was performed, but it is considered part of the more involved procedure (20912) and should not be coded. If the coding professional assigned the additional wound repair codes, it would be considered unbundling.

Mutually Exclusivet Edit

The mutually exclusive edit applies to improbable or impossible combinations of codes. For example, code 69601, Revision mastoidectomy; resulting in complete mastoidectomy, would never be performed with code 69604, Revision mastoidectomy; resulting in tympanoplasty. 

NCCI edits are included in most encoding software packages. The software vendors are responsible for maintaining up-to-date edits to support the coding/billing function. More information about NCCI edits can be found on the CMS Web site.

Medically Unlikely Edit

For Part B claims, CMS has developed “medical unlikely edits” to reduce error rates for items on the claim form that reference units of service. For each HCPCS/CPT code, the edits list the maximum units of service that a provider would report under most circumstances for a single beneficiary on a single date of service.

Smith, Gail. Basic Current Procedural Terminology and HCPCS Coding, 2010 Edition. Chicago, IL: AHIMA, 2010.

Melanie Endicott ( is a practice resources specialist at AHIMA.

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