T65.821 — Toxic effect of harmful algae and algae toxins, accidental (unintentional)
Is T65.821 billable?
No — T65.821 is a non-billable header code. T65.821 groups more specific codes and cannot be submitted on a claim. A valid ICD-10-CM code must be reported at the highest level of specificity available in its branch. Select one of the 3 billable codes beneath T65.821.
Billable codes under this header
T65.821 at a glance
| Code | T65.821 |
|---|---|
| Description | Toxic effect of harmful algae and algae toxins, accidental (unintentional) |
| Billable | No — header code |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
How is T65.821 listed in the Alphabetic Index?
The Alphabetic Index lists these routes under T65.82, the nearest indexed parent of T65.821. Use them to find the family, then select the specific code.
- Red tide
- Poisoning › algae and toxins (acute)
Inclusion terms
Alternative wording in documentation that is classified to T65.821.
- Toxic effect of harmful algae and algae toxins NOS
Excludes1 — never code together — inherited from T51-T65
The conditions below can never be reported together with T65.821 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- contact with and (suspected) exposure to toxic substances (Z77.-)
Use additional code — inherited from Chapter 19
Report an additional code alongside T65.821 to fully describe the condition. T65.821 is sequenced first.
- code to identify any retained foreign body, if applicable (Z18.-)
Use additional code — inherited from T51-T65
Report an additional code alongside T65.821 to fully describe the condition. T65.821 is sequenced first.
Excludes2 — not included here — inherited from Chapter 19
The conditions below are not part of T65.821, but a patient may have both at the same time. When documentation supports it, T65.821 and the excluded code may both be reported.
What codes fall under T65.821? (3)
How long has T65.821 existed?
T65.821 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.