Quick Answer: The United States uses ICD-10-CM for diagnoses and ICD-10-PCS for inpatient hospital procedures. ICD-10 replaced ICD-9-CM on October 1, 2015. ICD-11 took effect at the World Health Organization on January 1, 2022, but the US has not adopted it for coding and billing. In short, ICD-10 vs ICD-11 is not a choice US coders make today.
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If you are starting a medical coding career, you will hear about three versions of the International Classification of Diseases. However, US claims use only one of them today. Here is how they compare and what each means for your work.
ICD-9 vs ICD-10 vs ICD-11 Comparison
| ICD-9-CM | ICD-10-CM / PCS | ICD-11 | |
|---|---|---|---|
| Status in the US | Retired September 30, 2015 | Current code set since October 1, 2015 | Not adopted |
| Diagnosis code format | 3 to 5 characters, mostly numeric | 3 to 7 alphanumeric characters | Alphanumeric stem codes with optional extension codes |
| Inpatient procedures | ICD-9-CM Volume 3 | ICD-10-PCS, 7 characters | Not used for US procedures |
| Laterality and detail | Limited | Extensive (right, left, bilateral, encounter type) | Extensive, with postcoordination |
| Maintained by | NCHS and CMS (US version) | NCHS (CM) and CMS (PCS) | World Health Organization |
ICD-9-CM
ICD-9-CM was the US code set for decades. ICD-10 replaced it on October 1, 2015. Today, you will only see it when you work with historical records.
ICD-10-CM and ICD-10-PCS
Coders use ICD-10-CM for diagnoses in every healthcare setting. In contrast, hospitals use ICD-10-PCS only for inpatient procedures. For outpatient and physician procedures, coders report CPT and HCPCS Level II codes instead. Also, CMS and NCHS update ICD-10-CM every year on October 1, which is why coders need a new code book each fiscal year. The FY2027 code set took effect October 1, 2026.
ICD-11
The World Health Assembly adopted ICD-11, and it took effect for WHO reporting on January 1, 2022. In addition, it is fully digital and built for electronic health records. The US has not adopted ICD-11 for coding and billing, so you will not code with it on the CPC exam or on US claims. Any US transition would require federal rulemaking and years of preparation.
What This Means for New Coders
Focus on ICD-10-CM, CPT, and HCPCS Level II. The CPC exam tests those code sets, and US claims use them today. Learn more in our CPC Training program.
Frequently Asked Questions
Does the US use ICD-10 or ICD-11?
The US uses ICD-10-CM and ICD-10-PCS. However, the US has not adopted ICD-11 for coding and billing.
When did the US switch from ICD-9 to ICD-10?
October 1, 2015.
What is the difference between ICD-10-CM and ICD-10-PCS?
ICD-10-CM codes diagnoses in all settings. ICD-10-PCS codes inpatient hospital procedures only.
Is ICD-11 on the CPC exam?
No. The CPC exam tests ICD-10-CM, CPT, and HCPCS Level II.
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