T24.401S vs T24.409S

T24.401S (Corrosion of unspecified degree of unspecified site of right lower limb, except ankle and foot, sequela) compared with T24.409S (Corrosion of unspecified degree of unspecified site of unspecified lower limb, except ankle and foot, sequela), from the official CMS tabular data. T24.401S and T24.409S code the same condition on opposite sides.

Relationship

Review

Laterality relationship

T24.401S

Right

Corrosion of unspecified degree of unspecified site of right lower limb, except ankle and foot, sequela

↔

T24.409S

Unspecified

Corrosion of unspecified degree of unspecified site of unspecified lower limb, except ankle and foot, sequela

Same condition; these differ only in which side is documented.

These codes share a category and title and differ only in the side affected. The documentation decides which applies, and a bilateral code is reported only where the code set provides one.

Source: ICD-10-CM tabular list (laterality variant derived from the code title)

Can these codes be reported together?

Same condition, opposite side. T24.401S and T24.409S name the same condition on opposite sides of the body.

Same category and title, differing only in which side is affected — the documentation decides which one applies, and a bilateral code is reported only where the code set provides one.

Side by side

	T24.401SCorrosion of unspecified degree of unspecified site of right lower limb, except ankle and foot, sequela	T24.409SCorrosion of unspecified degree of unspecified site of unspecified lower limb, except ankle and foot, sequela
Billing status	Billable	Billable
Classification	S00-T88 — Injury, poisoning and certain other consequences of external causes	S00-T88 — Injury, poisoning and certain other consequences of external causes
Definition	Corrosion of unspecified degree of unspecified site of right lower limb, except ankle and foot, sequela is a billable ICD-10-CM diagnosis code (T24.401S).	Corrosion of unspecified degree of unspecified site of unspecified lower limb, except ankle and foot, sequela is a billable ICD-10-CM diagnosis code (T24.409S).
7th character	The appropriate 7th character is to be added to each code from category T24	The appropriate 7th character is to be added to each code from category T24
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]
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
Code first	(T51-T65) to identify chemical and intent	(T51-T65) to identify chemical and intent

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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources