The switch
From October 1, 2015, all HIPAA-covered entities had to report diagnoses with ICD-10-CM and inpatient procedures with ICD-10-PCS. ICD-9-CM codes are not valid for services on or after that date.
What changed for coders
| ICD-9-CM | ICD-10 | |
|---|---|---|
| Diagnosis codes | Mostly numeric, 3 to 5 characters | ICD-10-CM: alphanumeric, 3 to 7 characters, with laterality and encounter detail |
| Inpatient procedures | Volume 3, numeric, 3 to 4 digits | ICD-10-PCS: 7 characters built from tables |
| Detail | Limited specificity | Much greater specificity, which depends on detailed documentation |
What did not change
CPT® and HCPCS Level II remained the procedure codes for physician and outpatient services.
Why it still matters
Records, claims and research data from before October 2015 carry ICD-9-CM codes. Coders working on audits, data analysis or old claims may still need to read them. See the ICD-9-CM historical reference.
Sources
Checked Nov 3, 2026. Requirements and fees change, so confirm with the organisation before you register or pay.