2026 ICD-10-CM Diagnosis Code M20.012Mallet finger of left finger(s)

ICD-10-CM Codes›M00–M99›M20-M25›M20

ICD-10-CM M20.012
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M20.012 is a billable ICD-10-CM diagnosis code for mallet finger of left finger(s). 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acquired deformities (excluding foot).

Code Identity

ICD-10-CM Code
M20.012
Billable Status
Yes — Valid for Submission
Code Describes
Mallet finger of left finger(s)
Short Description
Mallet finger of left finger(s)
Same as the full description in the CMS dataset.
Parent Code
M20.01
Mallet finger

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM20Acquired deformities of fingers and toes
This CodeM20.012Mallet finger of left finger(s)

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acquired mallet finger of bilateral hands
  • Bilateral acquired deformity of finger of hands
  • Bilateral acquired deformity of hands
  • Mallet finger of left hand
  • Mallet finger of right hand
  • Rupture of extensor tendon of finger
  • Rupture of tendon of finger
  • Traumatic rupture of extensor tendon of finger
  • Traumatic tear of tendon of hand
  • Traumatic tear of tendon of left hand
  • Traumatic tear of tendon of right hand

Clinical ClassificationClinical

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

CCSR MUS023
Acquired deformities (excluding foot)
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Finger Injuries and Disorders

You use your fingers and thumbs to do everything from grasping objects to playing musical instruments to typing. When there is something wrong with them, it can make life difficult. Common problems include:

Read the full article at MedlinePlus

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

Convert M20.012 to ICD-9-CMHistory

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

ICD-9-CM
736.1 Mallet finger
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 M20.012Overview

Is M20.012 (Mallet finger) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report mallet finger of left finger(s) on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M20.012 group to?

When mallet finger of left finger(s) 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 M20.012?

Under the General Equivalence Mappings, mallet finger of left finger(s) converts to ICD-9-CM 736.1 (mallet finger). 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.