ICD-9 ↔ ICD-10 Crosswalk
Translate between ICD-9-CM and ICD-10-CM using official CMS General Equivalence Mappings (GEMs). Forward and reverse lookup — critical for pre-October 2015 claim appeals.
FY2027 update in progress. The FY2027 ICD-10-CM code set (effective 10/01/2026) is still loading, so a code may be missing or a deleted code may still show. Confirm against official CMS files before billing.
ICD-9-CM codes: 3–5 digits, often with decimal (e.g. 250.00). V-codes (V01–V91) and E-codes (E800–E999) also valid.
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Use forward mode to convert ICD-9 → ICD-10, or reverse mode to find which ICD-9 codes a given ICD-10 code came from.
When you need a GEM crosswalk
Appealing a denial on a claim with a pre-October 2015 service date. The payer may need to see the ICD-10 equivalent to process the appeal in their current system.
Retrospective audits covering service dates that span the ICD-9 to ICD-10 transition (2013–2016) often require crosswalk documentation.
Converting legacy EHR data or research datasets that used ICD-9 coding into ICD-10 for analytics or quality reporting.
Understanding how ICD-9's less-specific codes map to ICD-10's expanded specificity — particularly for new coders learning code structure.
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⚠️ GEM Mapping Limitations
- • Approximate mappings are the closest equivalent — the ICD-10 code may not capture all the clinical specificity of the original ICD-9 code
- • Combination mappings indicate the ICD-9 concept spans multiple ICD-10 codes — select the most appropriate based on clinical documentation
- • GEMs are a translation guide, not a coding authority. Final code selection must be based on physician documentation and AHA Coding Clinic guidance
- • Some ICD-9 codes have no ICD-10 equivalent — the ICD-10 system may require more specificity than the original ICD-9 documentation captured
Source: CMS General Equivalence Mappings (GEMs) — public domain government data. cms.gov/medicare