M21.4Header code — not billable
Flat foot [pes planus] (acquired)
- Chapter
- 13. Diseases of the musculoskeletal system and connective tissue
- Category
- M21
- Effective date
- October 1, 2026
Related codes in category M21
M21Other acquired deformities of limbsM21.0Valgus deformity, not elsewhere classifiedM21.00Valgus deformity, not elsewhere classified, unspecified siteYesM21.02Valgus deformity, not elsewhere classified, elbowM21.021Valgus deformity, not elsewhere classified, right elbowYesM21.022Valgus deformity, not elsewhere classified, left elbowYesM21.029Valgus deformity, not elsewhere classified, unsp elbowYesM21.05Valgus deformity, not elsewhere classified, hipM21.051Valgus deformity, not elsewhere classified, right hipYesM21.052Valgus deformity, not elsewhere classified, left hipYesM21.059Valgus deformity, not elsewhere classified, unspecified hipYesM21.06Valgus deformity, not elsewhere classified, knee
Frequently asked questions
What is ICD-10 code M21.4?
M21.4 is an ICD-10-CM diagnosis code for Flat foot [pes planus] (acquired).
Is M21.4 a billable code?
No. M21.4 is a category/header code, not billable on its own — use one of its more specific child codes instead.
What ICD-10-CM chapter is M21.4 in?
M21.4 falls under Chapter 13: Diseases of the musculoskeletal system and connective tissue.
When did M21.4 become effective?
M21.4 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to M21.4?
M21.4 belongs to category M21, which includes 12 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.