ICD-10-CM · FY 2026

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—Introduction

IConventions, general coding guidelines and chapter specific guidelines

I.AConventions for the ICD-10-CM
I.BGeneral Coding Guidelines
I.CChapter-Specific Coding Guidelines

IISelection of Principal Diagnosis

II.ACodes for symptoms, signs, and ill-defined conditions
II.BTwo or more interrelated conditions, each potentially meeting the definition for principal diagnosis.
II.CTwo or more diagnoses that equally meet the definition for principal diagnosis
II.DTwo or more comparative or contrasting conditions
II.FOriginal treatment plan not carried out
II.GComplications of surgery and other medical care
II.HUncertain Diagnosis
II.IAdmission from Observation Unit
II.JAdmission from Outpatient Surgery
II.KAdmissions/Encounters for Rehabilitation

IIIReporting Additional Diagnoses

III.APrevious conditions
III.BAbnormal findings
III.CUncertain Diagnosis

IVDiagnostic Coding and Reporting Guidelines for Outpatient Services

IV.ASelection of first-listed condition
IV.BCodes from A00.0 through T88.9, Z00-Z99, U00-U85
IV.CAccurate reporting of ICD-10-CM diagnosis codes
IV.DCodes that describe symptoms and signs
IV.EEncounters for circumstances other than a disease or injury
IV.FLevel of Detail in Coding
IV.HUncertain diagnosis
IV.IChronic diseases
IV.JCode all documented conditions that coexist
IV.KPatients receiving diagnostic services only
IV.LPatients receiving therapeutic services only
IV.MPatients receiving preoperative evaluations only
IV.NAmbulatory surgery
IV.ORoutine outpatient prenatal visits
IV.PEncounters for general medical examinations with abnormal findings
IV.QEncounters for routine health screenings

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ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026 (effective October 1, 2025), published by CMS and NCHS. Reproduced for reference — always verify against the official CMS release.