T20.40 is the authoritative medical code for Corrosion of unspecified degree of head, face, and neck, unspecified site. This classification is used in medical billing and clinical recording to specify the clinical criteria for corrosion of unspecified degree of head, face, and neck, unspecified site (ICD-10-CM T20.40), ensuring healthcare documentation aligns with 2026 federal coding standards.
Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.
Official Registry Overview & Definition
Corrosion of unspecified degree of head, face, and neck, unspecified site is a non-billable ICD-10-CM category code T20.40. A more specific billable subcode must be selected for claims submission. Includes: burns and corrosions of first degree erythema; burns and corrosions of second degree blistersepidermal loss; burns and corrosions of third degree deep necrosis of underlying tissue full- thickness skin loss. Excludes2 (not included here): burn and corrosion of ear drum (T28.41, T28.91); burn and corrosion of eye and adnexa T26.-; burn and corrosion of mouth and pharynx T28.0. Code first: 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. 7th character: The appropriate 7th character is to be added to each code from category T20.
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for T20.40 in the official ICD-10-CM tabular list.
Includes
Conditions the official ICD-10-CM tabular list includes under this code.
- burns and corrosions of first degree erythema
- burns and corrosions of second degree blistersepidermal 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.
- burn and corrosion of ear drum (T28.41, T28.91)
- burn and corrosion of eye and adnexa T26.-
- burn and corrosion of mouth and pharynx T28.0
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
- code from category T31 or T32 to identify extent of body surface involved
Frequently Asked Questions (FAQ) & Clinical Guidance
Can T20.40 be billed directly?
No. T20.40 (Corrosion of unspecified degree of head, face, and neck, unspecified site) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.
Does T20.40 require a 7th character?
Yes. The appropriate 7th character is to be added to each code from category T20.
Can T20.40 be reported alongside related conditions?
Per official ICD-10-CM Excludes2 instructions, T20.40 and the following are not considered part of each other and may both be reported when both conditions are present: burn and corrosion of ear drum (T28.41, T28.91); burn and corrosion of eye and adnexa (T26.-); burn and corrosion of mouth and pharynx (T28.0).
Does T20.40 need to be sequenced after another code?
Yes. Code first: (T51-T65) to identify chemical and intent.
Is an additional code needed with T20.40?
Use additional code(s) to specify: external cause code to identify place (Y92); code from category T31 or T32 to identify extent of body surface involved.
Nearest Codes in This Family
Official ICD-10-CM classifications closest to T20.40 in its code family, with their registry titles.
- T20 — Burn and corrosion of head, face, and neck
- T20-T25 — Burns and corrosions of external body surface, specified by site (T20-T25)
- T20-T32 — Burns and corrosions (T20-T32)
- T20.0 — Burn of unspecified degree of head, face, and neck
- T20.00 — Burn of unspecified degree of head, face, and neck, unspecified site
- T20.00XA — Burn of unspecified degree of head, face, and neck, unspecified site, initial encounter
- T20.00XD — Burn of unspecified degree of head, face, and neck, unspecified site, subsequent encounter
- T20.00XS — Burn of unspecified degree of head, face, and neck, unspecified site, sequela
- T20.01 — Burn of unspecified degree of ear [any part, except ear drum]
- T20.011 — Burn of unspecified degree of right ear [any part, except ear drum]
View all 40 codes in the T20 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), head (and face) (and neck)