M21.4

M21.4: Flat foot [pes planus] (acquired)

Non-billable headerICD-10-CM

M21.4 is a non-billable header ICD-10-CM code for flat foot [pes planus] (acquired). It cannot be billed on its own: choose one of the more specific child codes below.

Excludes1: never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

congenital pes planus (Q66.5-)

Excludes1 inherited from the categories above M21.4

A category’s note binds every code beneath it.

Written on M21: Other acquired deformities of limbs

acquired absence of limb (Z89.-)
congenital absence of limbs (Q71-Q73)
congenital deformities and malformations of limbs (Q65-Q66, Q68-Q74)

Excludes2 inherited from the categories above M21.4

Not part of this code, but both may be coded when both are present.

Written on M21: Other acquired deformities of limbs

acquired deformities of fingers or toes (M20.-)
coxa plana (M91.2)

Other codes that can never be billed with M21.4

Their own Excludes1 notes name this code, so the conflict is not listed above.

M23Internal derangement of knee
Q66.5Congenital pes planus

Risk adjustment

No CMS-HCC V28 category: this code does not change a RAF score.

Code history

Unchanged in every release from FY2024 to FY2027.

Code to one of these instead M21.4

3 child codes. Green means billable.