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ICD-10/T21.40

T21.40 ICD-10-CM Code: Corrosion of unspecified degree of trunk, unspecified site

Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.

Code Set: Valid FY2026 and FY2027. FY2026 took effect October 1, 2025.

Official Registry Overview & Definition

Corrosion of unspecified degree of trunk, unspecified site is a non-billable ICD-10-CM category code (T21.40). A more specific billable subcode must be selected for claims submission.

Official Tabular Instructional Notes

Sequencing, inclusion, and exclusion notes published for T21.40 in the official ICD-10-CM tabular list.

Includes

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

  • 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]

Excludes2 — Not Included Here

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

  • 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)

Code First

Underlying conditions that must be sequenced before this code.

  • (T51-T65) to identify chemical and intent

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • external cause code to identify place (Y92)
  • Use additional code from category T31 or T32 to identify extent of body surface involved

Frequently Asked Questions (FAQ) & Clinical Guidance

Can T21.40 be billed directly?

No. T21.40 (Corrosion of unspecified degree of trunk, unspecified site) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Does T21.40 require a 7th character?

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

Nearest Codes in This Family

Official ICD-10-CM classifications closest to T21.40 in its code family, with their registry titles.

  • T21.39 — Burn of third degree of other site of trunk
  • T21.39XA — Burn of third degree of other site of trunk, initial encounter
  • T21.39XD — Burn of third degree of other site of trunk, subsequent encounter
  • T21.39XS — Burn of third degree of other site of trunk, sequela
  • T21.4 — Corrosion of unspecified degree of trunk
  • T21.40XA — Corrosion of unspecified degree of trunk, unspecified site, initial encounter
  • T21.40XD — Corrosion of unspecified degree of trunk, unspecified site, subsequent encounter
  • T21.40XS — Corrosion of unspecified degree of trunk, unspecified site, sequela
  • T21.41 — Corrosion of unspecified degree of chest wall
  • T21.41XA — Corrosion of unspecified degree of chest wall, initial encounter

View all codes in the T21 family

Indexed Clinical Terms (1)

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code.

  • Corrosion (injury) (acid) (caustic) (chemical) (lime) (external) (internal), trunk