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T25.611A vs T25.611D

T25.611A (Corrosion of second degree of right ankle, initial encounter) compared with T25.611D (Corrosion of second degree of right ankle, subsequent encounter), from the official CMS tabular data.

Summary

These codes describe the same injury at different phases of treatment, so the 7th character that matches the encounter decides which one applies.

MedCoder-derived
What is different?

Title wording.The titles differ in one word, “initial” (T25.611A) versus “subsequent” (T25.611D): T25.611A is “Corrosion of second degree of right ankle, initial encounter”; T25.611D is “Corrosion of second degree of right ankle, subsequent encounter”.

Registry fact

Can these codes be reported together?

One per encounter.T25.611A and T25.611D code the same injury at a different phase of treatment, set by the 7th character. The 7th character records the type of care given at the encounter being coded (ICD-10-CM Official Guidelines, Section I.C.19.a), so one encounter takes one of these, not both.

MedCoder-derivedGuide: 7th characters: initial, subsequent, sequela

Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code.

Official rule

Is there an Excludes2 relationship?

None.Neither entry carries an Excludes2 note that names the other code.

Official rule

Is one more specific?

No.Neither is a subdivision of the other, and neither title is the unspecified form; they describe different conditions within category T25.

Registry fact

Is one a parent or header code?

No.Both are billable codes, and neither contains the other.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

Yes.Same injury, other encounter phase. T25.611A and T25.611D code the same injury at a different phase of treatment, set by the 7th character.

MedCoder-derivedGuide: 7th characters: initial, subsequent, sequela

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule.

Can these codes be reported together?

Review

Encounter relationship

T25.611A
Initial encounter
Corrosion of second degree of right ankle, initial encounter
↔
T25.611D
Subsequent encounter
Corrosion of second degree of right ankle, subsequent encounter

What we found

Same injury, other encounter phase.T25.611A and T25.611D code the same injury at a different phase of treatment, set by the 7th character.

The 7th character records the type of care given at the encounter being coded (ICD-10-CM Official Guidelines, Section I.C.19.a), so one encounter takes one of these, not both.

What to review

Use the 7th character that matches the encounter being coded (initial, subsequent or sequela); one encounter takes one of them.

Guide: 7th characters: initial, subsequent, sequelaCheck these on a claim

Why it matters

The 7th character records the phase of care for the encounter being coded, so a single encounter takes one of these characters, not several. Review whether both phases belong on the same episode of care.

Source / rule

ICD-10-CM Official Guidelines, Section I.C.19.a

Side by side

T25.611ACorrosion of second degree of right ankle, initial encounterT25.611DCorrosion of second degree of right ankle, subsequent encounter
Billing statusBillableBillable
ClassificationS00-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)
DefinitionCorrosion of second degree of right ankle, initial encounter is a billable ICD-10-CM diagnosis code (T25.611A).Corrosion of second degree of right ankle, subsequent encounter is a billable ICD-10-CM diagnosis code (T25.611D).
7th characterThe appropriate 7th character is to be added to each code from category T25The appropriate 7th character is to be added to each code from category T25
Includes
burns and corrosions of first degree [erythema]
burns and corrosions of second degree [blisters][epidermal loss]
burns and corrosions of third degree [deep necrosis of underlying tissue] [full- thickness skin loss]
burns and corrosions of first degree [erythema]
burns and corrosions of second degree [blisters][epidermal loss]
burns and corrosions of third degree [deep necrosis of underlying tissue] [full- thickness skin loss]
Code first
(T51-T65) to identify chemical and intent
(T51-T65) to identify chemical and intent
Use additional code
external cause code to identify place (Y92)
code from category T31 or T32 to identify extent of body surface involved
external cause code to identify place (Y92)
code from category T31 or T32 to identify extent of body surface involved

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on.

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Derived from the official CMS ICD-10-CM tabular data (FY2026). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources