T65.821 (Toxic effect of harmful algae and algae toxins, accidental (unintentional)) compared with T65.823 (Toxic effect of harmful algae and algae toxins, assault), from the official CMS tabular data. T65.821 and T65.823 code the same substance (Algae) with a different intent.
Same substance, different circumstance of exposure.
Same substance — assault (Algae)
Accidental poisoning, intentional self-harm, assault, undetermined intent, adverse effect and underdosing are mutually exclusive columns — exactly one applies to a given encounter.
Source: CMS Table of Drugs and Chemicals
Same substance, different intent. T65.821 and T65.823 code the same substance (Algae) with a different circumstance of exposure.
From the CMS Table of Drugs and Chemicals: accidental poisoning, intentional self-harm, assault, undetermined intent, adverse effect and underdosing are mutually exclusive columns — only one of them applies to a given encounter.
| T65.821Toxic effect of harmful algae and algae toxins, accidental (unintentional) | T65.823Toxic effect of harmful algae and algae toxins, assault | |
|---|---|---|
| Billing status | Non-billable header | Non-billable header |
| 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 harmful algae and algae toxins, accidental (unintentional) is a non-billable ICD-10-CM category code (T65.821). | Toxic effect of harmful algae and algae toxins, assault is a non-billable ICD-10-CM category code (T65.823). |
| 7th character | The appropriate 7th character is to be added to each code from category T65 | The appropriate 7th character is to be added to each code from category T65 |
| Includes | Toxic effect of harmful algae and algae toxins NOS | — |
| 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) | 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