M21.1 vs Q66.91
M21.1 (Varus deformity, not elsewhere classified) compared with Q66.91 (Congenital deformity of feet, unspecified, right foot), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. M21.1 carries an Excludes1 note covering Q66.91: “congenital deformities and malformations of limbs (Q65-Q66, Q68-Q74)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
No — do not report together. Q66.91 carries an Excludes1 note covering M21.1: “varus deformities (acquired) (M21.1-)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| M21.1Varus deformity, not elsewhere classified | Q66.91Congenital deformity of feet, unspecified, right foot | |
|---|---|---|
| Billing status | Non-billable header | Billable |
| Classification | M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99) | Q00-Q99 — Congenital Malformations, Deformations and Chromosomal Abnormalities (Q00-Q99) |
| Definition | Varus deformity, not elsewhere classified is a non-billable ICD-10-CM category code (M21.1). | Congenital deformity of feet, unspecified, right foot is a billable ICD-10-CM diagnosis code (Q66.91). |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources