W55 vs W56
W55 (Contact with other mammals) compared with W56 (Contact with nonvenomous marine animal), 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. W55 carries an Excludes1 note covering W56: “contact with marine mammals (W56.-)”
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
| W55Contact with other mammals | W56Contact with nonvenomous marine animal | |
|---|---|---|
| Billing status | Non-billable header Report instead: W55.01XA, W55.01XD, W55.01XS, W55.03XA, W55.03XD | Non-billable header Report instead: W56.01XA, W56.01XD, W56.01XS, W56.02XA, W56.02XD |
| Classification | V00-Y99 — External Causes of Morbidity (V00-Y99) | V00-Y99 — External Causes of Morbidity (V00-Y99) |
| Definition | Contact with other mammals is a non-billable ICD-10-CM category code (W55). | Contact with nonvenomous marine animal is a non-billable ICD-10-CM category code (W56). |
| 7th character | The appropriate 7th character is to be added to each code from category W55 | The appropriate 7th character is to be added to each code from category W56 |
| Includes | contact with saliva, feces or urine of mammal | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources