2026 ICD-10-CM Diagnosis Code M20.10Hallux valgus (acquired), unspecified foot

ICD-10-CM Codes›M00–M99›M20-M25›M20

ICD-10-CM M20.10
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M20.10 is a billable ICD-10-CM diagnosis code for hallux valgus (acquired), unspecified 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 acquired hallux valgus. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acquired foot deformities.

Code Identity

ICD-10-CM Code
M20.10
Billable Status
Yes — Valid for Submission
Code Describes
Hallux valgus (acquired), unspecified foot
Short Description
Hallux valgus (acquired), unspecified foot
Same as the full description in the CMS dataset.
Parent Code
M20.1
Hallux valgus (acquired)

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM20Acquired deformities of fingers and toes
This CodeM20.10Hallux valgus (acquired), unspecified foot

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acquired hallux valgus
  • Bunion
  • Hallux valgus
  • Hallux valgus AND bunion
  • Hallux valgus due to metatarsus primus varus
  • Hallux valgus interphalangeus
  • Infected bunion
  • Valgus deformity of lesser toe
  • Valgus deformity of toe

Clinical ClassificationClinical

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

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

Clinical InformationClinical

  • Hallux Valgus

    lateral displacement of the great toe (hallux), producing deformity of the first metatarsophalangeal joint with callous, bursa, or bunion formation over the bony prominence.

  • Bunion

    abnormal swelling of the inner aspect of the first metatarsal head affecting the first metatarsophalangeal joint.

  • Bunion, Tailor's

    abnormal swelling of the outer aspect of the fifth metatarsal head affecting the fifth metatarsophalangeal joint.

  • Metatarsophalangeal Joint

    the articulation between a metatarsal bone (metatarsal bones) and a phalanx.

  • Congenital Hallux Valgus

    hallux valgus that is present at birth.

  • Acquired Hallux Valgus

    a non-congenital deformity characterized by lateral deviation of the great toe.

  • Hallux Valgus

    a deformity characterized by lateral deviation of the great toe.

Patient EducationClinical

Foot Injuries and Disorders

Each of your feet has 26 bones, 33 joints, and more than 100 tendons, muscles, and ligaments. No wonder a lot of things can go wrong. Here are a few common problems:

Read the full article at MedlinePlus

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

Convert M20.10 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.
ICD-9-CM
735.0 Hallux valgus
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M20.10Overview

Is M20.10 (Hallux valgus (acquired)) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report hallux valgus (acquired), unspecified foot on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M20.10 group to?

When hallux valgus (acquired), unspecified 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 M20.10?

Under the General Equivalence Mappings, hallux valgus (acquired), unspecified foot converts to ICD-9-CM 727.1 (bunion) and 735.0 (hallux valgus). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.