1. What are NCCI edits?

NCCI or CCI stands for National Correct Coding Initiative.  In 1994, the Health Care Financing Administration (HCFA), now known as the Centers for Medicare and Medicaid Services (CMS), awarded a contract to AdminaStar Federal, the Indiana Medicare carrier, to define correct coding practices that would serve as the basis for national Medicare. In January 1996, CMS implemented the National Correct Coding Initiative. This initiative was developed to promote the correct coding of health care services by providers for Medicare beneficiaries and to prevent Medicare payments for improperly coded services. For example, CCI contains of automated edits provided to Medicare contractors to evaluate claim submissions when a provider bills more than one service for the same Medicare beneficiary on the same date of service. NCCI/CCI identifies pairs of services that, under Medicare coding/payment policy, a physician ordinarily should not bill for the same patient on the same day. NCCI/CCI edits also apply to the hospital outpatient prospective payment system (OPPS). Edits are updated quarterly and can be found on the CMS website

 The NCCI program includes three types of edits: Procedure-to-Procedure (PTP) Edits, Medically Unlikely Edits (MUE), and Add-on Code (AOC) Edits. 

  1. PTP (Procedure-to-Procedure) edits identify code pairs that CMS determined should not be billed together because one service inherently includes the other (bundled services) or two procedures are considered mutually exclusive. The code describing a broader and inclusive set of services is identified as being "comprehensive." The code describing a more discrete service that is actually a subcomponent of the broader service is described with the term "component." Since the component code represents a portion of the service described by the comprehensive code, it is therefore bundled and may not be reported separately. When two bundled procedures are submitted for the same patient during the same session, Medicare payers will ordinarily pay you only for the higher-valued procedure. A mutually exclusive edit might identify two different types of testing that yield equivalent results, or two or more procedures that are not usually performed during the same patient encounter on the same date of service (e.g., open and closed procedures). When two mutually exclusive services are submitted on a claim, only the service of lesser value will be reimbursed.
  2. Medically Unlikely edits (MUE) are meant to prevent payment for an inappropriate number/quantity of the same service on a single day. For example, an appendectomy has a MUE value of one, since a patient can only have one appendix.
  3. Add-on Code (AOC) edits consist of a listing of HCPCS/CPT Add-on Codes with their corresponding primary codes. An AOC edit describes a service that is almost always performed along with another primary service. An AOC is rarely eligible for payment if it’s the only procedure reported by a practitioner.

2. What do the NCCI/CCI columns 1 and 2 mean?

The column 1/column 2 correct coding edit table contains two types of code pair edits. The column 1 code generally represents the more significant procedure or service when reported with the column 2 code. When reported together, the column 1 code generally has a higher work RVU than the column 2 code. The "Mutually Exclusive" edits contain code pairs that Medicare believes should not be reported together where one code is assigned as the column 1 code and the other code is assigned as the column 2 code.

If a provider submits two codes of a code pair edit for the same Medicare beneficiary for the same date of service without an appropriate modifier, the column 1 code is paid. If clinical circumstances justify appending a NCCI/CCI-associated modifier to the column 2 code of a code pair edit, payment of both codes may be allowed.

Table 1

Column 1

Column 2

0=Not Allowed
9=Not Applicable










Table 1 provides a short sample of Column 2 edits for Current Procedural Terminology (CPT) 12001 (Simple wound repair, up to 2.5cm). CPT 64450 (peripheral nerve/branch block) in Column 2 is considered an integral part of the Column 1 service, but a modifier is appropriate to override the CCI edit for 64450 in combination with 12001 if the block is for a separate session, separate injury or separate anatomical area. CPT G0168 (Dermabond repair) is also considered an integral part of the simple laceration repair 12001 and a modifier is allowed to bypass the NCCI/CCI edit. Although you would not typically report both 12001 and G0168 for the same beneficiary on the same date of service, it is clinically conceivable that you would repair 2 distinct wounds on a single patient, one utilizing Dermabond and a second a simple repair utilizing sutures.

3. What modifiers can be used to support services with NCCI/CCI?

Table 2



Global Surgery





















































Table 2 provides a list of modifiers that may be used to support services included in the NCCI edits.

*These HCPCS alphanumeric codes refer to specific anatomic areas

  • E1-E4; anatomic areas of the eyelid
  • FA, F1-F9; the hands and digits
  • LC, LD, RC; anatomic areas of the coronary arteries
  • LM; left main coronary artery
  • RI; ramus intermedius coronary artery
  • LT; left side of the body
  • RT; right side of the body
  • TA, T1-T9; the foot and toes

4. How should modifier -59 be used under NCCI?

Modifier -59 is used to indicate a distinct procedural service. To appropriately report this modifier, append modifier -59 to the column 2 code to indicate that the procedure or service was independent from other services performed on the same day. The addition of this modifier indicates to the Medicare Administrative Contractors that the procedure or service represents a distinct procedure or service from others billed on the same date of service. In other words, this may represent a different session, different anatomical site or organ system, separate incision/excision, different lesion, or different injury or area of injury (in extensive injuries). When used with a NCCI/CCI edit, modifier -59 indicates that the procedures are different surgeries when performed at different operative areas or at different patient encounters.

If none of the anatomical modifiers can be used appropriately to describe the different sites, then the modifier -59 may be attached to indicate the separate location. Since modifier 59 bypasses many NCCI/CCI edits, providers should use careful consideration before applying this modifier and internal compliance plans should consider appropriate protocols for its application.

Effective January 2015, CMS established four HCPCS modifiers as a subset of the -59 modifier to define a "Distinct Procedural Service."   Providers should use the X {ESPU} modifiers in accordance with their published definitions (and perhaps after consultation with their respective MACs) for CMS.  Modifier -59 should not be used unless no other more specific modifier is appropriate.

The four modifiers include:

  1. XE (Separate Encounter): A service that is distinct because it occurred during a separate encounter
  2. XS (Separate Structure): A service that is distinct because it was performed on a separate organ/structure
  3. XP (Separate Practitioner): A service that is distinct because it was performed by a different practitioner
  4. XU (Unusual Non-Overlapping Service): The use of a service that is distinct because it does not overlap usual components of the main service

Note, the -X {EPSU} modifiers are more selective versions of the -59 modifier.  Thus, it would be incorrect to include both modifiers on the same line.

For more information regarding the specific modifiers:

Medicare Learning Network, Proper Use of Modifiers 59, XE, XP, XS, & XU

Transmittal 1422: Specific Modifiers for Distinct Procedural Services

5. How should modifier -25 be reported with NCCI/CCI?

Modifier -25 should be appended to an evaluation and management (E/M) code when reported with a separately reportable procedure on the same day of service. Appending modifier -25 to the E/M code indicates to Medicare contractors or fiscal intermediaries that the physician performed a significant, separately identifiable E/M service above and beyond the other service provided. Modifier -25 may be appended to E&M services reported with minor procedures (global periods of 000 or 010 days) or procedures not covered by global surgery rules (global indicator XXX).

6. What are Medically Unlikely Edits (MUE)?

CMS developed Medically Unlikely Edits (MUEs) to reduce the paid claims error rate for Part B claims. A MUE specifies a maximum number of units of service allowable (under most circumstances) for a single Healthcare Common Procedural Coding System (HCPCS)/CPT code billed by a provider on a single date of service for a single beneficiary. Of note, not all HCPCS/CPT codes have MUE.

MUE was implemented January 1, 2007, and is utilized to adjudicate claims at Carriers, Fiscal Intermediaries, and Durable Medical Equipment (DME) Medicare Administrative Contractors (MACs).

Although CMS publishes most MUE values (the maximum number of reportable units) on its website, other MUE values are confidential and are for CMS and CMS Contractors' use only.

Inquiries about a specific claim should be addressed to the claims processing contractor.

7. What are some examples of Medically Unlikely Edits (MUE)?

The MUE maximum value for 99291 (critical care) is 1. 99291 may only be submitted one time by the same provider for the same beneficiary per calendar day. For additional critical care services beyond 74 minutes, 99292 is used in 30-minute increments. The MUE maximum value for 99292 is 8.

Control of nasal hemorrhage codes each have an MUE of 1. The MUE value for endotracheal intubation is 2 units. CPR has an MUE value of 3 units. Wound and laceration repair codes each have an MUE value of 1 unit.

8. How do I report medically reasonable and necessary units of service in excess of a Medically Unlikely Edit (MUE) value?

Since each line of a claim is adjudicated separately against the MUE value for the code on that line, the appropriate use of Current Procedural Terminology (CPT) modifiers to report the same code on separate lines of a claim will enable a provider/supplier to report medically reasonable and necessary units of service in excess of an MUE value. CPT modifiers such as -76 (repeat procedure by same physician), -77 (repeat procedure by another physician), anatomic modifiers (e.g., RT, LT, F1, F2), -91 (repeat clinical diagnostic laboratory test), and -59 (distinct procedural service) will accomplish this purpose. Modifier -59 or -X{EPSU} should be utilized only if no other modifier describes the service. Since this approach bypasses the MUE process, providers should use careful consideration before reporting multiple units of the same service for the same beneficiary on the same calendar date in excess of the MUE values. Internal compliance plans should consider appropriate protocols for any claims exceeding the MUE values.

9. Do other payers beyond Medicare recognize NCCI/CCI edits?

Private payers use a combination of NCCI/CCI edits and proprietary edits to determine "covered services" in accordance with payer benefit plans.  Payer payment policies frequently draw from CPT, NCCI/CCI and Medicare, as well as applying payer-specific proprietary edits.  Thus, NCCI/CCI may be used by private payers in some form, but often NCCI/CCI is only one of a number of tools utilized by private payers to determine separately covered services.

Medicaid utilizes the Medicaid National Correct Coding Initiative

10. Where might I obtain more in-depth information on NCCI/CCI edits on the CMS website?

This page on the CMS website includes a number of relevant downloads, including the "NCCI Policy Manual for Medical Services."

Updated February 2024



The American College of Emergency Physicians (ACEP) has developed the Reimbursement & Coding FAQs and Pearls for informational purposes only.   The FAQs and Pearls have been developed by sources knowledgeable in their fields, reviewed by a committee, and are intended to describe current coding practice. However, ACEP cannot guarantee that the information contained in the FAQs and Pearls is in every respect accurate, complete, or up to date.

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