ICD-10-CM

International Classification of Diseases, 10th Revision, Clinical Modification. Diagnosis code set used on US healthcare claims since October 1, 2015. Contains 98,186 codes in the 2026 edition organized into 22 chapters (A00-Z99). Codes are 3 to 7 characters. Updated annually on October 1. Used on every CMS-1500 and UB-04 claim. Replaces ICD-9-CM (which had 14,000 diagnosis codes) and adds laterality, encounter type, and significantly more clinical specificity.