ICD-10 Coding Rules
Medicare Code Editor (MCE) validation rules for ICD-10-CM codes
6,568 codes
across 7 rule categoriesNewborn Only (Age 0)
Codes only valid for patients age 0 (newborns/neonates)
42 codes
Pediatric (Ages 0-17)
Codes intended for pediatric patients (ages 0-17)
125 codes
Maternity (Ages 9-64)
Codes intended for maternity patients (ages 9-64)
2,475 codes
Adult (Ages 15+)
Codes intended for adult patients (ages 15+)
856 codes
Manifestation Code
Codes that cannot be used as principal diagnosis
422 codes
Questionable Admission
Diagnoses usually insufficient for hospital admission
30 codes
Unacceptable Principal Dx
Codes unacceptable as principal diagnosis
2,618 codes
About Medicare Code Edits
The Medicare Code Editor (MCE) is software used by CMS to detect and report coding errors in Medicare claims. These edits help ensure accurate coding and prevent claim denials.
Age Edits: Detect inconsistencies between patient age and diagnosis codes. For example, a newborn-only code used for an adult patient.
Manifestation Codes: Must be used with an underlying cause code and cannot be the principal diagnosis.
Principal Diagnosis Edits: Some codes describe circumstances rather than illnesses and are unacceptable as principal diagnosis.
Source: CMS Definitions of Medicare Code Edits v43.0 (FY 2026)