T58 vs T71.9XXA
T58 (Toxic effect of carbon monoxide) compared with T71.9XXA (Asphyxiation due to unspecified cause, initial encounter), 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. T71.9XXA carries an Excludes1 note covering T58: “asphyxia from carbon monoxide (T58.-)”
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
| T58Toxic effect of carbon monoxide | T71.9XXAAsphyxiation due to unspecified cause, initial encounter | |
|---|---|---|
| Billing status | Non-billable header Report instead: T58.01XA, T58.01XD, T58.01XS, T58.02XA, T58.02XD | Billable |
| Classification | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) |
| Definition | Toxic effect of carbon monoxide is a non-billable ICD-10-CM category code (T58). | Asphyxiation due to unspecified cause, initial encounter is a billable ICD-10-CM diagnosis code (T71.9A). |
| 7th character | The appropriate 7th character is to be added to each code from category T58 | The appropriate 7th character is to be added to each code from category T71 |
| Includes | asphyxiation from carbon monoxide toxic effect of carbon monoxide from all sources | Suffocation (by strangulation) due to unspecified cause Suffocation NOS Systemic oxygen deficiency due to low oxygen content in ambient air due to unspecified cause Systemic oxygen deficiency due to mechanical threat to breathing due to unspecified cause |
| Use additional code | code(s): for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70) personal history of foreign body fully removed (Z87.821) | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources