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T21.3 ICD-10-CM Code: Burn of third degree of trunk

Compare with another codeCheck this code on a claim

Billing Status: NO. This is a non-billable ICD-10-CM code: report a more specific billable code beneath it.

Coding at a Glance

7th character
Required — see the character table on this page
Tabular directives
4 inclusion terms · 3 Excludes2 · 2 use-additional codes

Not billable · FY2027A non-billable heading in the tabular list: report a more specific code beneath it.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too; the Instructions section marks which is which.

Use additional codeReport with this code when documented
  • external cause code to identify the source, place and intent of the burn (X00-X19, X75-X77, X96-X98, Y92)
  • code from category T31 or T32 to identify extent of body surface involved
Excludes2Not included here; may be reported together
  • burns and corrosion of axilla (T22.- with fifth character 4)
  • burns and corrosion of scapular region (T22.- with fifth character 6)
  • burns and corrosion of shoulder (T22.- with fifth character 5)
IncludesWhat this code covers
  • burns and corrosion of hip region
  • 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]

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for T21.3 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on T21.3 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • burns and corrosion of hip region inherited from T21
  • burns and corrosions of first degree [erythema] inherited from T20-T25
  • burns and corrosions of second degree [blisters][epidermal loss] inherited from T20-T25
  • burns and corrosions of third degree [deep necrosis of underlying tissue] [full- thickness skin loss] inherited from T20-T25

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from T21

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • external cause code to identify the source, place and intent of the burn (X00-X19, X75-X77, X96-X98, Y92)
  • Use additional code from category T31 or T32 to identify extent of body surface involved inherited from T20-T25

7th Character Guide

"The appropriate 7th character is to be added to each code from category T21"

  • A — initial encounter
  • D — subsequent encounter
  • S — sequela

How the encounter character is assigned. “Initial encounter” means the patient is receiving active treatment for the condition — it is not limited to the first visit, and a different or new provider giving active treatment still assigns it. “Subsequent encounter” covers care during the healing or recovery phase after active treatment. “Sequela” is for complications or conditions that arise as a direct result of the original condition.

ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19.a (paraphrased by MedCoder).

Variant codes in this family

T21.30XA, T21.30XD, T21.30XS, T21.31XA, T21.31XD, T21.31XS, T21.32XA, T21.32XD

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for T21.3

MedCoder structured workflow — derived from this code’s own official record

Before you code T21.3

  1. T21.3 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

    ReviewT21.30, T21.31, T21.32, T21.33, T21.34

    See the relationships section · Guide: How to choose an ICD-10-CM code →

  2. A 7th character is required in this family. Confirm the documented encounter: initial (active treatment), subsequent (healing or recovery phase), or sequela. T21.3 is not valid without one. “Initial” means active treatment, not the first visit (Guidelines I.C.19.a).

    See the 7th Character Guide · Guide: 7th characters: initial, subsequent, sequela →

  3. Confirm the injury type, the anatomical site at the most specific level documented, laterality where the family codes it, and the encounter for the 7th character. Each injury is coded separately unless the classification provides a combination code, and a superficial injury is not coded when a more severe injury of the same site is documented. Injury chapter guidelines (Guidelines I.C.19.b, I.C.19.b.1).

    Guide: 7th characters: initial, subsequent, sequela →

Choose the right path

  1. Does the documentation support one of the more specific codes beneath T21.3?
    Yes → Select that code and continue the checks below on its own page.
    No → T21.3 cannot be reported as written; query for the specificity its subcategory needs.

    ReviewT21.30, T21.31, T21.32, T21.33, T21.34

  2. Is the encounter phase documented — active treatment, healing or recovery, or a sequela?
    Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
    No → The code is invalid without its 7th character — query for the missing element.

Consider T21.3. Then work the Use Additional Code note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Anatomical site
At the most specific level the record states; a site the classification separates cannot be assumed from a procedure or a measurement.
Encounter type
Active treatment, healing or recovery phase, or sequela — the basis of the 7th character (Guidelines I.C.19.a).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.
External cause, place and activity
For the external cause codes reported with the injury or poisoning, where documented (Guidelines I.C.20.a).

Official instructions as workflow

  • Excludes2 — not part of T21.3(3 notes)

    Coding workflow: The conditions named in this note are not included in T21.3. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareT22

    See the official tabular notes · Guidelines I.A.12.b

  • Use Additional Code — after identifying T21.3(2 notes)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with T21.3 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    ReviewY92, T31, T32

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The patient returns during the healing or recovery phase after active treatment of the same condition.

Coding question: Which 7th character applies?

Path: Review the official 7th-character definitions for this family in the 7th Character Guide.

Reason: “Initial encounter” means active treatment, not the first visit; care during recovery takes “subsequent encounter”, and a complication arising from the original condition takes “sequela” (Guidelines I.C.19.a).

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with T21.3?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

ReviewY92, T31, T32

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse T21.3 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of T21.3 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • T21.30XA— Encounter relationship (Review)

    Same underlying diagnosis, different encounter phase.

    The same diagnosis at a different phase of care; one encounter takes one 7th character.

    What moves you there: Documentation of a initial encounter moves the case to T21.30XA.

    Full comparison: T21.3 vs T21.30XA →

  • T21.30XD— Encounter relationship (Review)

    Same underlying diagnosis, different encounter phase.

    The same diagnosis at a different phase of care; one encounter takes one 7th character.

    What moves you there: Documentation of a subsequent encounter moves the case to T21.30XD.

    Full comparison: T21.3 vs T21.30XD →

  • T22— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of burns and corrosion of axilla adds T22; it is not part of this code and both may be reported when both are documented.

    Full comparison: T21.3 vs T22 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Burn of third degree of trunk is a non-billable ICD-10-CM category code (T21.3). A more specific billable subcode must be selected for claims submission.

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

  1. A 7th character applies in this family. Confirm the documented encounter matches the character assigned. See the official 7th-character definitions and this code’s variants
  2. 2 Use Additional Code instructions — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
  3. 3 Excludes2 entries — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name T21.3 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 2 Excludes1 notes: T07 — Unspecified multiple injuries (via T21.-), T66 — Radiation sickness, unspecified (via T21.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 123 Excludes2 notes: S00 — Superficial injury of head (via T21.-), S00-S09 — Injuries to the head (S00-S09) (via T21.-), S01 — Open wound of head (via T21.-), S02 — Fracture of skull and facial bones (via T21.-), S03 — Dislocation and sprain of joints and ligaments of head (via T21.-), S04 — Injury of cranial nerve (via T21.-), S05 — Injury of eye and orbit (via T21.-), S06 — Intracranial injury (via T21.-), S07 — Crushing injury of head (via T21.-), S08 — Avulsion and traumatic amputation of part of head (via T21.-), S09 — Other and unspecified injuries of head (via T21.-), S10 — Superficial injury of neck (via T21.-), S10-S19 — Injuries to the neck (S10-S19) (via T21.-), S11 — Open wound of neck (via T21.-), S12 — Fracture of cervical vertebra and other parts of neck (via T21.-), S13 — Dislocation and sprain of joints and ligaments at neck level (via T21.-), S14 — Injury of nerves and spinal cord at neck level (via T21.-), S15 — Injury of blood vessels at neck level (via T21.-), S16 — Injury of muscle, fascia and tendon at neck level (via T21.-), S17 — Crushing injury of neck (via T21.-), +103 more.

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Contextual Map

Every relationship of T21.3 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run T21.3 with these 18 related codes in Claim Check

Hierarchy

Use Additional Code (25)

Referenced by Excludes1 notes

Referenced by Excludes2 notes (123)

Nearest codes (40)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Common coding questions

MedCoder editorial

Can T21.3 be billed directly?

No. T21.3 (Burn of third degree of trunk) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Does T21.3 require a 7th character?

Yes. The appropriate 7th character is to be added to each code from category T21.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "T21.3 — Burn of third degree of trunk." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/t21.3-burn-of-third-degree-of-trunk

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Burn of third degree of trunk

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to T21.3 in its code family, with their registry titles.

View all codes in the T21 family