CMS Pub. 100-04, ch. 23, § 20.9

The Centers for Medicare & Medicaid Services (CMS) developed the NCCI program to promote national

correct coding methodologies and to control improper coding leading to inappropriate payment in Part B

claims. CMS developed its coding policies based on coding conventions defined in the American Medical

Association’s CPT Professional codebook, CMS national and local policies and edits, coding guidelines

developed by national societies, analysis of standard medical and surgical practices, and a review of current

coding practices. An overview of the NCCI program for Procedure-to-Procedure (PTP) edits, Medically

Unlikely Edits (MUEs), Add-on Code (AOC) edits and additional information sources are found on the

Medicare NCCI Edits webpage.

The Medicare NCCI Policy Manual (also known as the Coding Policy Manual) shall be used by Medicare

Administrative Contractors (MACs) as a general reference tool that explains the rationale for NCCI edits.

The purpose of the NCCI PTP edits is to prevent improper payment when incorrect Healthcare Common

Procedure Coding System (HCPCS)/Current Procedural Terminology (CPT) code combinations are

reported. The Medicare NCCI Edits webpage contains separate tables of edits for physicians/practitioners

and outpatient hospital services. Additional information regarding types of tables is available in the How to

Use The Medicare National Correct Coding Initiative (NCCI) Tools MLN booklet.

The purpose of the NCCI MUE program is to prevent improper payments when services are reported with

incorrect units of service (UOS). CMS developed MUEs to reduce the paid claims error rate for Part B

claims. An MUE for a HCPCS/CPT code is the maximum UOS that a provider or supplier would report

under most circumstances for a single beneficiary on a single date of service. The Medicare NCCI Medically

Unlikely Edits (MUEs) webpage contains separate tables of edits for physicians/practitioners, outpatient

hospital services, and durable medical equipment.

An AOC is a HCPCS/CPT code that describes a service that, with rare exception, is performed in

conjunction with another primary service by the same practitioner. An AOC is rarely eligible for payment if

it is the only procedure reported by a practitioner.

CMS posted the Correspondence Language Manual for Medicare Services on the Medicare NCCI

Correspondence Language Manual webpage for use by the Medicare Contractors to answer routine

correspondence inquiries about the NCCI PTP and MUE edits. The general correspondence language

paragraphs explain the rationale for the edits. The section-specific examples add further explanation to the

PTP or MUE edits and are sorted by edit rationale and HCPCS/CPT code section (00000, 10000, 20000,

etc.). Please refer to the Introduction of the Correspondence Language Manual for additional guidance about

its use.

20.9.1 - Correct Coding Modifier Indicators (CCMI) and HCPCS Codes Modifiers

(Rev . 10878, Issued: 07-15-2021, Effective:08-16-2021; Implementation:08-16-2021)

The National Correct Coding Initiative (NCCI) File Formats continue to include a Correct Coding Modifier

Indicator (CCMI) for the Column One / Column Two Correct Coding edit file. This indicator determines

whether an NCCI PTP-associated modifier causes the code pair to bypass the edit. The CCMI will be either

a “0,” “1,” or a “9.” The definitions of each are:

0 = an NCCI PTP-associated modifier is not allowed and will not bypass the edit.

1 = an NCCI PTP-associated modifier is allowed and will bypass the edit.

9 = The use of NCCI PTP-associated modifiers is not specified. This indicator is used for all code pairs that

have a deletion date that is the same as the effective date. This indicator prevents blank spaces from

appearing in the indicator field.