Compliance Guide
NCCI Edits Explained: PTP Edits, MUEs and Modifiers
What the National Correct Coding Initiative does, how procedure-to-procedure edits and medically unlikely edits work, and when an NCCI-associated modifier is appropriate.
In this article
The National Correct Coding Initiative (NCCI) is CMS's program to prevent improper payment when codes are reported together that should not be, or when a code is reported in units that are implausible. NCCI edits run automatically in Medicare claims processing, and state Medicaid programs are required to use NCCI methodologies too. Many commercial payers apply NCCI-style edits as well.
What are the two main types of NCCI edits?
| Edit type | What it checks | Example of the problem it prevents |
|---|---|---|
| Procedure-to-procedure (PTP) | Pairs of codes that generally should not be billed together for the same patient, same provider, same date | Billing a component of a procedure separately from the comprehensive procedure |
| Medically unlikely edits (MUE) | The maximum units of a code a provider would report for one beneficiary on one date of service in most circumstances | Reporting more units than anatomy or clinical practice makes plausible |
PTP edits exist in separate tables for practitioners and for hospital outpatient services, so the same code pair can behave differently depending on the claim type.
How do PTP modifier indicators work?
Each PTP edit carries a modifier indicator:
- 0 — the codes cannot be reported together, even with a modifier.
- 1 — an NCCI-associated modifier may bypass the edit when clinical circumstances justify it and the documentation supports a separate and distinct service.
- 9 — the edit is not active (it was deleted retroactively).
Which modifiers are NCCI-associated?
NCCI-associated modifiers include anatomic modifiers (such as LT, RT, E1–E4, FA–F9, TA–T9, LC, LD, LM, RC, RI), global surgery modifiers (24, 25, 57, 58, 78, 79), modifier 27, 59, 91, and the more specific X{EPSU} modifiers:
- XE — separate encounter
- XS — separate structure/organ
- XP — separate practitioner
- XU — unusual non-overlapping service
CMS has encouraged the use of the more specific X modifiers instead of modifier 59 where one applies.
How do MUEs work?
Each MUE value has an MUE adjudication indicator (MAI):
- MAI 1 — a claim-line edit. If the units on a line exceed the value, that line is denied. When clinically justified and documented, additional units may be reported on separate lines with an appropriate modifier.
- MAI 2 — a date-of-service edit based on policy. Units for the code on the same date are added together; units above the value are not payable, and appeals generally will not change that.
- MAI 3 — a date-of-service edit based on clinical benchmarks. Units above the value are denied, but may be paid on appeal when the documentation supports medical necessity.
Not all MUE values are published; CMS publishes most of them.
How often does NCCI change?
NCCI edit files are updated quarterly (January, April, July and October). Edits can also be added, revised or deleted between quarterly releases. Always use the edit table in effect for the date of service. Our coding calendar tracks the quarterly cycle.
Practical checklist
Key takeaways
Source
CMS — National Correct Coding Initiative (NCCI) Edits
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Additional references
Medical coding trainer and author with more than 22 years of experience, an AHIMA Approved ICD-10 Trainer, and the managing editor of MedicalCodingUpdates.com.
Educational information only. Verify coding decisions against current official guidelines, code sets and applicable payer policies. Read the full disclaimer.
