ICD-10 code T25.112S: First degree burn of left ankle, sequela

Key takeaways

T25.112S is a billable ICD-10-CM code for burn of first degree of left ankle, sequela, and it is current in the FY2026 code set.

The 7th character S marks a sequela, meaning the original burn has healed but a residual condition persists. Do not confuse it with D, which covers an encounter during active healing.

Position 6 sets the site, where 1 is the ankle and 2 is the foot. Position 7 sets the side, where 1 is right and 2 is left.

Sequencing rule: The code for the nature of the sequela is listed first, and T25.112S follows as the cause code.

Practice management software like Pabau submits claims through Claim.MD, so payer edits run before a sequela claim ever leaves the practice.

ICD-10 code T25.112S is a billable ICD-10-CM code for burn of first degree of left ankle, sequela. It applies when a healed first-degree burn of the left ankle leaves a residual condition behind, such as discoloration or lingering itch. The code sits in category T25, which covers burns and corrosion of the ankle and foot.

Choosing between the 7th characters D and S decides whether the claim pays. This reference breaks down each character in the code and the sequencing rule for sequela. It also covers the documentation payers expect, the neighboring T25 codes, and the errors that cause denials.

ICD-10 code T25.112S: Quick reference details

T25.112S is a current, billable code in the FY2026 ICD-10-CM code set. The Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics maintain that code set. The ankle and foot burn codes in category T25 have been part of ICD-10-CM since the US adopted it in October 2015.

What does T25.112S mean? Breaking down the code

Each character in T25.112S carries clinical meaning. Misreading any one character leads to a wrong code and, in most payer systems, a denial. Here is what each position means.

The first three characters (T25) place this code within category T25 of ICD-10-CM, which covers all burns and corrosions of the ankle and foot. The digit “1” at the fifth position signals first-degree burn severity.

The second “1” identifies the ankle rather than the foot within that category. The digit “2” then specifies left-side laterality, which ICD-10-CM requires for injury codes on paired body parts. The final character “S” is the 7th character extension denoting sequela, covered in depth below.

Reading those two digits the wrong way round turns a left ankle burn into a right foot burn. Four first-degree sequela codes make the pattern obvious. T25.111S is the right ankle, T25.112S the left ankle, T25.121S the right foot, T25.122S the left foot.

First degree burns: Clinical definition and criteria

Accurate degree selection is the foundation of burn coding. Using T25.112S requires documentation that the original injury was a first-degree burn. Upcoding to second degree without clinical evidence is an audit risk. Downcoding causes its own problems when the record supports a more severe burn.

First-degree burns involve damage confined to the outermost layer of the skin, the epidermis. They produce erythema (redness) and pain without blister formation. No full skin-thickness damage occurs. Second-degree burns, by contrast, involve partial-thickness epidermal and dermal damage with blistering.

• Erythema only: Skin appears red but intact
• No blistering: Absence of vesicles or bullae
• Epidermis intact: No open wound
• Heals without scarring: Typically resolves in 3-7 days
• Pain and tenderness: Present at the time of the initial injury

When the original first-degree burn has healed and a residual condition persists, the sequela encounter uses T25.112S. That residual condition might be skin discoloration, pruritus, or hypersensitivity at the ankle. The record from the original encounter should be available to confirm the initial degree classification. See the CDC/NCHS ICD-10-CM web tool for the official tabular description and applicable-to notes.

Understanding the sequela designation (7th character S)

The 7th character is the single most consequential element in T25.112S for billing purposes. ICD-10-CM uses three 7th characters for the burn codes in categories T20 to T25, and confusing them generates denials and compliance exposure.

Sequela vs subsequent encounter: The key distinction

The distinction between D and S drives more coding errors than any other element in burn injury claims. The rule is straightforward. Use D while the burn wound is still healing. Use S once the burn has healed and the current complaint is a residual consequence of that injury.

A patient returning three weeks after a first-degree ankle burn for a follow-up wound check uses T25.112D. That same patient returning six months later with persistent hyperpigmentation at the healed burn site uses T25.112S. The clinical note must document that the original burn has resolved and describe the current late-effect condition.

ICD-10-CM coding guidelines for burn sequela

The ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19.d, establish the sequencing rules that govern T25.112S. These rules are mandatory, not advisory. Incorrect sequencing is a coding error even when the individual codes are otherwise correct.

Coding a burn sequela usually takes two codes. The code describing the nature of the sequela is sequenced first, such as a scar contracture or post-burn pruritus. T25.112S then follows as the cause code, identifying the original burn as the underlying etiology. Correct sequencing keeps the claim compliant and reduces the risk of audit findings.

• Code for the nature of the sequela first, such as L90.5 for scar conditions or a symptom code for post-burn pain
• T25.112S follows as the etiology or cause code
• The sequela code is never used alone without documenting the residual condition
• Do not report the injury code with 7th character S and the active burn code together for the same site
• Refer to the AAPC ICD-10-CM code lookup for index references and coding notes specific to T25.112S

The Official Guidelines also note that S covers any condition resulting from a prior injury once active treatment has concluded. This applies however much time has passed since the original burn. A sequela encounter can happen years later, if the residual condition is only now being addressed. Applying that rule is what produces a clean claim submission on the first attempt.

Documentation requirements to support T25.112S

Payers require specific documentation before accepting a sequela code. Miss one element and the record cannot answer an auditor’s first question. These five points are what a reviewer looks for.

• Prior burn history documented: The record must establish that a first-degree burn of the left ankle happened at an earlier encounter. That can be the patient’s own record, or a documented history section in the current note.
• Degree confirmed: The original burn must be documented as first-degree, meaning erythema only and no blistering. Without that, the degree character “1” has no evidentiary support.
• Left ankle specified: Laterality must be explicit in the documentation. “Ankle burn” with no left or right designation does not support T25.112S.
• Current condition is a residual effect: The note for the current encounter must describe a condition that follows directly from the prior burn. Examples include skin discoloration, scarring, localized pruritus, or hypersensitivity at the burn site.
• Original burn resolved: The note should indicate the wound has healed, which is what separates this from an active-healing subsequent encounter.

Without all five elements above, a claim for T25.112S is coding without adequate documentation. That creates audit liability even when the clinical picture genuinely supports the code.

T25 category: Related ICD-10-CM codes for burns of the ankle and foot

T25.112S sits within a structured code hierarchy. Knowing the adjacent codes prevents errors when laterality, degree, or encounter type differs from what you first assumed.

The WHO ICD-10 classification system holds the global parent categories that ICD-10-CM derives its burn coding structure from. US coders should reference the ICD-10-CM tabular list rather than the international version for billing purposes.

Billing and reimbursement for T25.112S claims

Submitting T25.112S means pairing it with the appropriate sequela condition code on the claim. Many clearinghouses run edits on that pair before transmission, so a reversed order can bounce back before it reaches the payer at all.

Reimbursement follows the service performed, not the burn code. T25.112S carries no payment of its own. It explains why the residual condition exists, which is what supports medical necessity for the evaluation or treatment billed alongside it.

Common coding errors to avoid with T25.112S

Five errors account for the bulk of T25.112S rejections on burn injury claims. Each one is preventable with a short check before submission.

• Using D instead of S after wound closure: This is the most common error. Once the wound has fully healed, later encounters for residual effects take the S character. Continuing with T25.112D after closure misstates the clinical status and creates overpayment liability on audit.
• Missing laterality: Submitting T25.119S when the documentation clearly states left ankle is a specificity failure. ICD-10-CM guidelines require the most specific code available, so use T25.112S when the record names the left ankle.
• Sequencing T25.112S first: The cause code must follow the code for the nature of the sequela. Putting T25.112S in the principal diagnosis position, when a residual condition code is also present, violates Section I.C.19.d. Payers that edit on sequencing will deny on this basis.
• Using T25.112S without documenting the residual condition: The sequela code needs a companion code for the current condition. Sending T25.112S alone, with no code describing what the patient has at this encounter, is incomplete coding.
• Applying T25.112S to the wrong site: This code is specifically for the ankle. Burns of the foot take a 2 in position 6, not a 1. Confusing the two subsites creates specificity errors that payers catch on claims editing.

A pre-bill review takes about two minutes. Check these four points before the claim goes out:

• The 7th character matches the documented healing status
• Laterality in the code matches the clinical note
• T25.112S sits second, after the nature-of-sequela code
• A current-condition code is present on the claim

When one of these slips through, the denial codes on the remittance advice name the edit that fired. That tells you what to correct before you resubmit.

Approximate synonyms and applicable-to terms

ICD-10-CM includes approximate synonyms and applicable-to notes that help coders and CDI specialists confirm T25.112S is the right code. These terms appear in coding software, EHR pick lists, and code reference tools.

• Burn of first degree of left ankle, sequela
• Superficial burn of left ankle, late effect
• First-degree burn left ankle sequela
• Epidermal burn of left ankle, sequela
• Late effect of first-degree burn of left ankle

These synonyms help when you are querying an encoder or an ICD-10-CM database and the exact code is not to hand. The CMS ICD-10-CM code files carry the full tabular list and index entries, which are the definitive source for resolving a synonym.

How claims software catches T25.112S sequencing errors

A sequencing error usually surfaces weeks later, on the remittance. A coder reopens the chart, puts the two codes in the right order, and resubmits. The work gets done twice and the payment lands a month late.

Practice management software like Pabau moves that check upstream. Claims go out through a built-in Claim.MD connection, which runs payer edits before submission to thousands of US insurance payers. A pair a payer’s edits reject comes back while the claim is still in your system.

Electronic remittance advice then returns into the same patient record, so a CARC denial reason sits on the claim line it belongs to. Pabau’s approach to cleaner claims management means a coder reviewing T25.112S rejections works from the record, not a separate portal export.

Tired of sequela coding denials?

Pabau sends claims through Claim.MD, so payer edits run on your ICD-10-CM code pairs and sequencing before submission. You catch sequela errors in the workflow instead of in the appeals queue.

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Conclusion

The choice between D and S decides whether a burn sequela claim pays. Degree, site, and side all come straight off the chart. The 7th character is the only one you have to reason about, which is why it is the one that goes wrong.

So make wound closure a documented event rather than an assumption. Once the note says the burn has healed and names the residual condition, T25.112S is defensible. The only step left is putting it second, behind the code for the condition the patient actually has today.

Fix the process at the front end and these claims stop coming back. Book a demo to see how Pabau catches a sequencing problem before the claim leaves your practice.

Continue your research

Need to understand how clearinghouse integrations catch sequela errors before submission? Our guide to Claim.MD as a medical claims clearinghouse explains how payer edits and sequencing checks work at the clearinghouse level.

Want to see where a sequela code fits in the wider claim lifecycle? What is medical billing covers the end-to-end process, from encounter through to payment posting.

Looking for guidance on building a clean ICD-10-CM claim? Superbill documentation and structure walks through what a complete superbill looks like when injury sequela codes are involved.

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