Erin Saunders Jun 13, 2022 10:56:18 AM 10 min read

What to Know About the National Correct Coding Initiative (NCCI Edits)

Have you ever received denials that refer to the NCCI Edits? They’re more complex than you might think.

The National Correct Coding Initiative (NCCI) was created by the Centers for Medicare and Medicaid Systems (CMS) to encourage correct coding and to prevent incorrect payments. There are three types of edits:

  • Procedure To Procedure Edits (PTP)
  • Medical Unlikely Edits (MUE)
  • Add-On Code Edits (AOC).

All edits are based on current coding rules and guidelines, national and local Medicare policies, and standard medical and surgical practices. During claim processing, the system compares every CPT/HCPCS Code billed for the same patient and date of service by the same provider and reviews them against the NCCI edit tables.

 PTP Edits

In the PTP table, every code is assigned to “Column 1” or “Column 2.” If a provider reports a code from each column of an edit pair, then the Column 1 Code is eligible for payment while the Column 2 Code will be denied, unless specific circumstances allow the use of a modifier to unbundle the codes. Examples of those modifiers include 25, 59, the “X” modifiers (XE, XS, XP, XU), or any of the anatomical modifiers.

Under the NCCI Edits, there are 3 types of PTP indicators: “0” the codes can never be reported together on the same date of service; “1” the codes can be reported together on the same date of service under certain conditions with the use of a modifier; or “9” which indicates that the combination of codes can be billed together without a modifier.

  • Indicator 0 – CPT 52648 & 52281 have an edit; CPT 52648 is a Column 1 and CPT 52281 is a Column 2 so these codes cannot be billed together, regardless of a modifier, because the service described by 52648 includes the service defined by 52281.
  • Indicator 1 – CPT 50590 & 52005 have an edit; CPT 50590 is a Column 1 and CPT 52005 is a Column 2 so when medically appropriate and documented correctly, these two codes can be billed together with a modifier.
  • Indicator 9 – CPT 50590 & 52332 have no edits so there are no stipulations about billing them together except correct documentation and medical necessity.


MUE is an edit applied against a claim for services billed by one provider to one patient on one date of service to determine whether they are medically necessary and appropriate. MUE’s have 3 types of indicators called MUE Adjudication Indicators (MAI). The “Indicator 1” is a Claim Line Edit that reviews the number of units billed for the code and, when appropriate, allows a separate charge line with a modifier for the additional unit(s). The “Indicator 2” denotes an Absolute Date of Service Edit which limits the total units per day. CMS will not pay for any unit over the MUE value. The “Indicator 3” is for the Date of Service Edit which also limits the units per day, but CMS may pay over the MUE value when appealed with documentation which supports the medical necessity of the extra units.

  • MAI Indicator 1 – CPT 99486 has an MUE of 4 and the MAI 1 because when billed for multiple units, each code should be on a separate charge line and only the first doesn’t require a modifier.
  • MAI Indicator 2 – CPT 52441 has an MUE of 1 and an MAI of 2 because there is another code for this service when additional units are performed.
  • MAI Indicator 3 – CPT 52442 has an MUE of 6 and an MAI of 3 because additional units may be documented as medically necessary and proven by appeal.

AOC Edits

The last type of edit, Add-On Codes (AOC), relates to codes that are reported in combination with a primary code by the same provider. AOC are indicated with a “+” symbol in the CPT book. There are 3 types of AOC based on the allowed primary code lists and whether CMS or the claim contractors defined the list. Type I codes have a limited number of primary CPT codes from CMS, so they are eligible for payment if a code from that list is eligible for the same provider, patient, and date of service. Type II codes are eligible for payment if an applicable primary code defined by the claim contractor is also eligible for payment. The Type III Add-On Code list of primary codes determined by CMS is combined with the claim contractors’ own list of corresponding primary CPT codes.

Still have questions about the NCCI Edits? Our team is here to help. Reach out to start the conversation today.