Y99.1 vs Y99.8
Y99.1 (Military activity) compared with Y99.8 (Other external cause status), 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. Y99.1 carries an Excludes1 note covering Y99.8: “activity of off duty military personnel (Y99.8)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
No — do not report together. Y99.8 carries an Excludes1 note covering Y99.1: “military activity (Y99.1)”
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
| Y99.1Military activity | Y99.8Other external cause status | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | V00-Y99 — External Causes of Morbidity (V00-Y99) | V00-Y99 — External Causes of Morbidity (V00-Y99) |
| Definition | Military activity is a billable ICD-10-CM diagnosis code (Y99.1). | Other external cause status is a billable ICD-10-CM diagnosis code (Y99.8). |
| Includes | — | Activity NEC Activity of child or other family member assisting in compensated work of other family member Hobby not done for income Leisure activity |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources