M21.40: Flat foot [pes planus] (acquired), unspecified foot
M21.40 is the billable ICD-10-CM diagnosis code for Flat foot [pes planus] (acquired), unspecified foot. It is a fully specified code, so it can be reported on a claim (subject to clinical documentation and your payer's rules).
Frequently asked questions
What is ICD-10-CM code M21.40?
M21.40 is the ICD-10-CM diagnosis code for Flat foot [pes planus] (acquired), unspecified foot. It belongs to category M21 (Other acquired deformities of limbs).
Is M21.40 a billable code?
Yes. M21.40 is a billable, fully specified ICD-10-CM code, so it can be used on a claim (subject to documentation and payer rules).
What category does M21.40 belong to?
M21.40 is part of ICD-10-CM category M21 — Other acquired deformities of limbs, which has 248 billable codes.
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Informational only, not coding or medical advice. Verify against the official ICD-10-CM (FY2026) and your payer's guidelines.
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