2026 ICD-10-CM Diagnosis Code Q66.90Congenital deformity of feet, unspecified, unspecified foot

ICD-10-CM Codes›Q00-Q99›Q65-Q79›Q66

ICD-10-CM Q66.90
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q66.90 is a billable ICD-10-CM diagnosis code for congenital deformity of feet, unspecified, 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. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Musculoskeletal congenital conditions.

Code Identity

ICD-10-CM Code
Q66.90
Billable Status
Yes — Valid for Submission
Code Describes
Congenital deformity of feet, unspecified, unspecified foot
Short Description
Congenital deformity of feet, unspecified, unspecified foot
Same as the full description in the CMS dataset.
Parent Code
Q66.9
Congenital deformity of feet, unspecified

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ65-Q79Congenital malformations and deformations of the musculoskeletal system
CategoryQ66Congenital deformities of feet
This CodeQ66.90Congenital deformity of feet, unspecified, unspecified foot

Present on Admission (POA)Billing

Q66.90 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Ankylosis of metatarsophalangeal joint
  • Congenital abnormal shape of rib
  • Congenital ankylosis of metatarsophalangeal joint of fourth toe
  • Congenital ankylosis of metatarsophalangeal joint of second toe
  • Congenital ankylosis of metatarsophalangeal joint of third toe
  • Congenital anomaly of foot
  • Congenital anomaly of toe
  • Congenital deformity of foot
  • Congenital deformity of foot and ankle
  • Congenital deformity of toe
  • Congenital pectus excavatum
  • Deformity of sternum
  • Finger hyperphalangy, toe anomalies, severe pectus excavatum syndrome
  • Hand-foot-genital syndrome
  • Hyperphalangy
  • Pectus deformity of chest
  • Pectus excavatum

Clinical ClassificationClinical

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

CCSR MAL008
Musculoskeletal congenital conditions
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Birth Defects

A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of pregnancy. One out of every 33 babies in the United States is born with a birth defect.

The full article covers:

  • What are birth defects?
  • What causes birth defects?
  • Who is at risk of having a baby with birth defects?
  • How are birth defects diagnosed?
  • What are the treatments for birth defects?
  • Can birth defects be prevented?

Read the full article at MedlinePlus

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

Code History & ChangesHistory

Replacement Q66.90 replaces the following previously assigned code(s):

  • Q66.9 - Congenital deformity of feet, unspecified
FY 2020AddedAdded to the ICD-10-CM code setEffective October 1, 2019.
FY 2021–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Q66.90Overview

Is Q66.90 (Congenital deformity of feet, unspecified) a billable code?

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

What MS-DRG does Q66.90 group to?

When congenital deformity of feet, unspecified, 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.

Is Q66.90 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for congenital deformity of feet, unspecified, unspecified foot on inpatient claims.

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.