National Correct Coding Initiative

CMS developed the NCCI to promote national correct coding methodologies and eliminate improper coding of Medicare Part B claims. Coding policies are based on coding conventions defined in the AMA’s CPT professional manual, national and local Medicare policies and edits, coding guidelines developed by national societies, standard medical and surgical practices, and a review of current coding practices.

Edits are developed based on anatomic considerations, HCPCS/CPT code descriptors, CPT instructions, CMS policies, nature of service/procedure, nature of analyte, nature of equipment and clinical judgement.

There are three types of NCCI edits:

• NCCI PTP Edits
  • Define pairs of HCPCS and CPT codes that providers shouldn't report together for various reasons. PTP edits prevent improper payments when you report incorrect code combinations. Each edit has a Column 1 and a Column 2 HCPCS/CPT code.
• Medically Unlikely Edits
  • MUEs are a critical part of the NCCI, focusing on limiting the units of service that can be appropriately billed for a given HCPCS/CPT code based on the majority of claims submitted. This helps ensure that the billing aligns with what is clinically reasonable and reduces the potential for overbilling or errors.
• Add-on Codes
  • HCPCS/CPT code that describes a service that is performed in conjunction with the primary service by the same practitioner. An AOC is rarely eligible for payment if it’s the only procedure reported by a practitioner.

Revised 5/28/2025