M21.4
ICD-10Non-billable categoryFlat foot [pes planus] (acquired)
Official ICD-10-CM descriptor (FY2026)
Flat foot [pes planus] (acquired)
M21.4 is a category heading, not a billable code. CMS does not accept it on a claim; report one of the more specific codes beneath it.
Excludes1
Not coded here. An Excludes1 code should never be reported at the same time as the code above it.
- congenital pes planus (Q66.5-)
ICD-10-CM FY2026 defines 3 codes beneath M21.4. See the ICD-10-CM index for what this site publishes.
Related codes in M21
- M21.0Valgus deformity, not elsewhere classifiedcategory
- M21.1Varus deformity, not elsewhere classifiedcategory
- M21.2Flexion deformitycategory
- M21.3Wrist or foot drop (acquired)category
- M21.5Acquired clawhand, clubhand, clawfoot and clubfootcategory
- M21.6Other acquired deformities of footcategory
- M21.7Unequal limb length (acquired)category
- M21.8Other specified acquired deformities of limbscategory
- M21.9Unspecified acquired deformity of limb and handcategory
Where this code sits
- Parent code
- M21
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ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.