Non-Billable / Non-Specific Code
ICD-10-CM M21.4 is the diagnosis code for Flat foot [pes planus] (acquired). This code falls under the section "Other joint disorders" within Chapter 13 — Diseases of the musculoskeletal system and connective tissue (M00-M99). It is a non-billable/non-specific ICD-10-CM code that should not be used for reimbursement. A more specific sub-code is required for billing. Medical coders and healthcare providers use this code to document and classify diagnoses in electronic health records, insurance claims, and clinical databases.
The following conditions should never be coded at the same time as M21.4. They are mutually exclusive:
Understanding where M21.4 sits in the ICD-10-CM classification helps ensure proper coding:
No, M21.4 is a non-billable/non-specific code. You should use a more specific sub-code for billing and reimbursement.
M21.4 is the ICD-10-CM diagnosis code for "Flat foot [pes planus] (acquired)". It is used by healthcare providers to classify and document this condition in medical records and insurance claims.
The parent code of M21.4 is M21 ("Other acquired deformities of limbs"). M21.4 provides a more specific classification within this category.
M21.4 is located in Section M20-M25 — "Other joint disorders" within Chapter 13 of the ICD-10-CM Tabular List.
M21.4 has 3 sub-code(s) that provide more specific detail: M21.40, M21.41, M21.42.
Use M21.4 when the patients documented diagnosis matches "Flat foot [pes planus] (acquired)" and the clinical documentation supports this level of specificity. Always verify with the latest ICD-10-CM guidelines and payer requirements.
The ICD-10-CM code for Flat foot [pes planus] (acquired) is M21.4.
No, M21.4 is non-billable. Use a more specific sub-code for primary diagnosis billing.
M21.4 is in Chapter 13 of the ICD-10-CM Tabular List.
Type 1 Excludes for M21.4 include: congenital pes planus (Q66.5-).
Yes, M21.4 is a valid ICD-10-CM code for the 2026 fiscal year, subject to official CMS updates.