T65.821A — Toxic effect of harmful algae and algae toxins, accidental (unintentional), initial encounter
Is T65.821A billable?
Yes — T65.821A is billable for FY2027. T65.821A is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. T65.821A may be submitted for encounters from October 1, 2026 through September 30, 2027.
T65.821A at a glance
| Code | T65.821A |
|---|---|
| Description | Toxic effect of harmful algae and algae toxins, accidental (unintentional), initial encounter |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
| 7th character "A" | initial encounter |
What does the 7th character "A" mean in T65.821A?
In T65.821A, the 7th character A means initial encounter. The 7th character is required for T65.821A to be a valid, complete code.
Same condition, different episode of care — switch the 7th character:
Which MS-DRGs does T65.821A group to?
T65.821A sits in MDC 21 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 917Poisoning and Toxic Effects of Drugs with MCCmedical
- 918Poisoning and Toxic Effects of Drugs without MCCmedical
How is T65.821A listed in the Alphabetic Index?
The Alphabetic Index lists these routes under T65.82, the nearest indexed parent of T65.821A. 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 T65.821A.
- 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 T65.821A 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 T65.821A to fully describe the condition. T65.821A 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 T65.821A to fully describe the condition. T65.821A is sequenced first.
Excludes2 — not included here — inherited from Chapter 19
The conditions below are not part of T65.821A, but a patient may have both at the same time. When documentation supports it, T65.821A and the excluded code may both be reported.
How long has T65.821A existed?
T65.821A 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.