2026 ICD-10-CM Diagnosis Code T25.729SCorrosion of third degree of unspecified foot, sequela
T25.729S is a billable ICD-10-CM diagnosis code for corrosion of third degree of unspecified foot, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 604 through 605. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury, sequela.
Code Identity
Code Classification
Present on Admission (POA)Billing
T25.729S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Coding GuidelinesGuidance
The ICD-10-CM makes a distinction between burns and corrosions. The burn codes are for thermal burns, except sunburns, that come from a heat source, such as a fire or hot appliance. The burn codes are also for burns resulting from electricity and radiation. Corrosions are burns due to chemicals. The guidelines are the same for burns and corrosions.
Sequence first the code that reflects the highest degree of burn when more than one burn is present.
- When the reason for the admission or encounter is for treatment of external multiple burns, sequence first the code that reflects the burn of the highest degree.
- When a patient has both internal and external burns, the circumstances of admission govern the selection of the principal diagnosis or first-listed diagnosis.
- When a patient is admitted for burn injuries and other related conditions such as smoke inhalation and/or respiratory failure, the circumstances of admission govern the selection of the principal or first-listed diagnosis.
Current burns (T20-T25) are classified by depth, extent and by agent (X code). Burns are classified by depth as first degree (erythema), second degree (blistering), and third degree (full-thickness involvement).
Classify burns of the same local site (three-character category level, T20-T28) but of different degrees to the subcategory identifying the highest degree recorded in the diagnosis.
The appropriate 7th character is to be added to each code from block Burn and corrosion of ankle and foot (T25). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Burns
A burn is damage to your body's tissues caused by heat, chemicals, electricity, sunlight, or radiation. Scalds from hot liquids and steam, building fires and flammable liquids and gases are the most common causes of burns. Another kind is an inhalation injury, caused by breathing smoke.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T25.729S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T25.729SOverview
Is T25.729S (Corrosion of third degree of unspecified foot) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report corrosion of third degree of unspecified foot, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T25.729S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the corrosion of third degree of unspecified foot itself has resolved, not the original event.
What MS-DRG does T25.729S group to?
When corrosion of third degree of unspecified foot, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 604, 605, with relative weights from 0.9160 to 1.4721 depending on complications. Higher weights mean higher Medicare reimbursement.
Is T25.729S exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for corrosion of third degree of unspecified foot, sequela on inpatient claims.
What is the ICD-9 equivalent of T25.729S?
Under the General Equivalence Mappings, corrosion of third degree of unspecified foot, sequela converts to ICD-9-CM 906.7 (late eff burn extrem NEC). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
