W99 vs Y63.2
W99 (Exposure to other man-made environmental factors) compared with Y63.2 (Overdose of radiation given during therapy), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. W99 carries an Excludes1 note covering Y63.2: “failure in dosage of radiation or temperature during surgical and medical care (Y63.2-Y63.5)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| W99Exposure to other man-made environmental factors | Y63.2Overdose of radiation given during therapy | |
|---|---|---|
| Billing status | Non-billable header | Billable |
| Classification | V00-Y99 — External Causes of Morbidity (V00-Y99) | V00-Y99 — External Causes of Morbidity (V00-Y99) |
| Definition | Exposure to other man-made environmental factors is a non-billable ICD-10-CM category code (W99). | Overdose of radiation given during therapy is a billable ICD-10-CM diagnosis code (Y63.2). |
| 7th character | The appropriate 7th character is to be added to code W99 | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources