2026 ICD-10-CM Diagnosis Code M21.621Bunionette of right foot

ICD-10-CM Codes›M00–M99›M20-M25›M21

ICD-10-CM M21.621
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M21.621 is a billable ICD-10-CM diagnosis code for bunionette of right foot. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 564 through 566. Coders also document this condition as bilateral tailor's bunion of feet. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acquired foot deformities.

Code Identity

ICD-10-CM Code
M21.621
Billable Status
Yes — Valid for Submission
Code Describes
Bunionette of right foot
Short Description
Bunionette of right foot
Same as the full description in the CMS dataset.
Parent Code
M21.62
Bunionette

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM21Other acquired deformities of limbs
This CodeM21.621Bunionette of right foot

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral tailor's bunion of feet
  • Mass of joint of bilateral feet
  • Mass of joint of left foot
  • Mass of joint of right foot
  • Tailor's bunion of left foot
  • Tailor's bunion of right foot

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS021
Acquired foot deformities
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Toe Injuries and Disorders

Fourteen of the 26 bones in your feet are in your toes. The toes, particularly your big toe, help you move and keep your balance. Playing sports, running, stubbing your toe, and dropping something on your foot can damage your toes. Wearing shoes that are too loose or too tight can also cause toe problems.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M21.621 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
727.1 Bunion
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement M21.621 replaces the following previously assigned code(s):

  • M20.11 - Hallux valgus (acquired), right foot
FY 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M21.621Overview

Is M21.621 (Bunionette) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report bunionette of right foot on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M21.621 group to?

When bunionette of right foot is the principal diagnosis on an inpatient stay, it groups to MS-DRG 564, 565, 566, with relative weights from 0.7493 to 1.5436 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M21.621?

Under the General Equivalence Mappings, bunionette of right foot converts to ICD-9-CM 727.1 (bunion). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.