T25.799A — Corrosion of third degree of multiple sites of unspecified ankle and foot, initial encounter
Is T25.799A billable?
Yes, but T25.799A will trip a Medicare edit. T25.799A is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, CMS lists T25.799A under Medicare Code Editor edit 20, “Unspecified code” — meaning a code specifying laterality (right, left or bilateral) exists in the same family. On an inpatient claim this triggers the edit, because CMS holds that there are very limited circumstances in which laterality cannot be documented.
T25.799A at a glance
| Code | T25.799A |
|---|---|
| Description | Corrosion of third degree of multiple sites of unspecified ankle and foot, 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 T25.799A?
In T25.799A, the 7th character A means initial encounter. The 7th character is required for T25.799A to be a valid, complete code.
Same condition, different episode of care — switch the 7th character:
What Medicare edits apply to T25.799A?
The Medicare Code Editor screens inpatient claims before they are grouped. These edits name T25.799A directly.
A code specifying laterality (right, left or bilateral) exists in the same family. CMS holds that there are very limited circumstances in which laterality cannot be documented.
Which MS-DRGs does T25.799A group to?
T25.799A sits in MDC 22 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.
- 927Extensive Burns or Full Thickness Burns with MV >96 Hours with Skin Graftsurgical
- 933Extensive Burns or Full Thickness Burns with MV >96 Hours without Skin Graftmedical
As a secondary diagnosis, T25.799A is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG. It also carries Hospital-Acquired Condition category 05.
How is T25.799A listed in the Alphabetic Index?
The Alphabetic Index lists these routes under T25.799, the nearest indexed parent of T25.799A. Use them to find the family, then select the specific code.
- Corrosion › lower › limb › multiple sites, except ankle and foot › ankle and foot › third degree (injury) (acid) (caustic) (chemical) (lime) (external) (internal)
Code first — inherited from T25.7
The underlying condition below must be sequenced before T25.799A. T25.799A describes a manifestation and cannot be the principal or first-listed diagnosis.
- (T51-T65) to identify chemical and intent
Use additional code — inherited from Chapter 19
Report an additional code alongside T25.799A to fully describe the condition. T25.799A is sequenced first.
- code to identify any retained foreign body, if applicable (Z18.-)
Use additional code — inherited from T20-T25
Report an additional code alongside T25.799A to fully describe the condition. T25.799A is sequenced first.
Use additional code — inherited from T25.7
Report an additional code alongside T25.799A to fully describe the condition. T25.799A is sequenced first.
- external cause code to identify place (Y92)
Excludes2 — not included here — inherited from Chapter 19
The conditions below are not part of T25.799A, but a patient may have both at the same time. When documentation supports it, T25.799A and the excluded code may both be reported.
How long has T25.799A existed?
T25.799A 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.