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Q66.50 ICD-10-CM Code: Congenital pes planus, unspecified foot

Compare with another codeCheck this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
4 Excludes1

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too; the Instructions section marks which is which.

Excludes1Never report with this code
  • pes planus, acquired (M21.4)
  • reduction defects of feet (Q72.-)
  • valgus deformities (acquired) (M21.0-)
  • varus deformities (acquired) (M21.1-)

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 564 — OTHER MUSCULOSKELETAL SYSTEM AND CONNECTIVE TISSUE DIAGNOSES WITH MCC (MDC 08)
  • MS-DRG 565 — OTHER MUSCULOSKELETAL SYSTEM AND CONNECTIVE TISSUE DIAGNOSES WITH CC (MDC 08)
  • MS-DRG 566 — OTHER MUSCULOSKELETAL SYSTEM AND CONNECTIVE TISSUE DIAGNOSES WITHOUT CC/MCC (MDC 08)
  • MS-DRG 795 — NORMAL NEWBORN (MDC 15)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for Q66.50 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on Q66.50 itself; “inherited from” names the category or block whose note applies here.

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Coder workflow for Q66.50

MedCoder structured workflow — derived from this code’s own official record

Before you code Q66.50

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, Q66.50 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewQ66.51, Q66.52

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

  2. Laterality is coded in this family. Confirm the side documented — right, left, or bilateral — and select the matching code (this page’s code: unspecified). The unspecified-side code applies only when the record states no side. Laterality is assigned from the documented side; where a bilateral code exists and both sides are documented, it is used instead of two unilateral codes (Guidelines I.B.13).

    ReviewQ66.51 · right, Q66.52 · left

    Guide: Laterality coding →

  3. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with Q66.50. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — Q66.50 is appropriate when the documentation goes no further.

    ReviewQ66.51, Q66.52

  2. Does the documentation support a condition named in Q66.50’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewM21.4, Q72, M21.0, M21.1

  3. Is the side documented?
    Yes → Select the code for the documented side (or the bilateral code when both sides are documented and one exists).
    No → Use the unspecified-side code only when the record states no side; a query is the alternative.

    ReviewQ66.51 · right, Q66.52 · left

Consider Q66.50. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Laterality
Right, left or bilateral as documented; unspecified only when the record states no side (Guidelines I.B.13).
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes1 — check before selecting Q66.50(4 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with Q66.50: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareM21.4, Q72, M21.0, M21.1

    See the official tabular notes · Guidelines I.A.12.a

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewQ66.51, Q66.52

Documentation: Both the condition Q66.50 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewM21.4, Q72, M21.0, M21.1

Documentation: The record documents the condition on one side only.

Coding question: Which code in this family applies?

Path: Select the sibling code for the documented side.

Reason: Laterality is assigned from the documented side; the unspecified-side code is for records that state no side (Guidelines I.B.13).

ReviewQ66.51 · right, Q66.52 · left

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse Q66.50 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of Q66.50 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • M21.4— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of pes planus, acquired moves the case to M21.4; the two are not reported together unless documented as unrelated.

    Full comparison: Q66.50 vs M21.4 →

  • Q72— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of reduction defects of feet moves the case to Q72; the two are not reported together unless documented as unrelated.

    Full comparison: Q66.50 vs Q72 →

  • M21.0— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of valgus deformities (acquired) moves the case to M21.0; the two are not reported together unless documented as unrelated.

    Full comparison: Q66.50 vs M21.0 →

  • M21.1— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of varus deformities (acquired) moves the case to M21.1; the two are not reported together unless documented as unrelated.

    Full comparison: Q66.50 vs M21.1 →

  • Q66.51— Laterality relationship (Review)

    Same condition; these differ only in which side is documented.

    The same condition on the other side; the documented side decides, and a bilateral code, where one exists, replaces the pair when both sides are documented.

    What moves you there: A documented right side moves the case to Q66.51.

    Full comparison: Q66.50 vs Q66.51 →

  • Q66.52— Laterality relationship (Review)

    Same condition; these differ only in which side is documented.

    The same condition on the other side; the documented side decides, and a bilateral code, where one exists, replaces the pair when both sides are documented.

    What moves you there: A documented left side moves the case to Q66.52.

    Full comparison: Q66.50 vs Q66.52 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Congenital pes planus, unspecified foot is a billable ICD-10-CM diagnosis code (Q66.50).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name Q66.50 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 4 Excludes1 notes: M20 — Acquired deformities of fingers and toes (via Q66.-), M21 — Other acquired deformities of limbs (via Q66.-), M21.4 — Flat foot [pes planus] (acquired) (via Q66.5.-), M24.3 — Pathological dislocation of joint, not elsewhere classified (via Q66.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Excludes2 note: M95 — Other acquired deformities of musculoskeletal system and connective tissue (via Q66.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 4 MS-DRGs: DRG 564 (MDC 08), DRG 565 (MDC 08), DRG 566 (MDC 08), DRG 795 (MDC 15).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):MAL008 — Musculoskeletal congenital conditions (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same condition, opposite side

Same category and title, differing only in which side of the body is affected.

Q66.51 — Congenital pes planus, right foot (right)Compare Q66.50 vs Q66.51 →, Q66.52 — Congenital pes planus, left foot (left)Compare Q66.50 vs Q66.52 →

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Musculoskeletal congenital conditions).

Q66.222 — Congenital metatarsus adductus, left foot, Q66.229 — Congenital metatarsus adductus, unspecified foot, Q66.3 — Other congenital varus deformities of feet, Q66.30 — Other congenital varus deformities of feet, unspecified foot, Q66.31 — Other congenital varus deformities of feet, right foot, Q66.32 — Other congenital varus deformities of feet, left foot, Q66.4 — Congenital talipes calcaneovalgus, Q66.40 — Congenital talipes calcaneovalgus, unspecified foot, Q66.41 — Congenital talipes calcaneovalgus, right foot, Q66.42 — Congenital talipes calcaneovalgus, left foot, Q66.51 — Congenital pes planus, right foot, Q66.52 — Congenital pes planus, left foot, Q66.6 — Other congenital valgus deformities of feet, Q66.7 — Congenital pes cavus, Q66.70 — Congenital pes cavus, unspecified foot, Q66.71 — Congenital pes cavus, right foot, Q66.72 — Congenital pes cavus, left foot, Q66.80 — Congenital vertical talus deformity, unspecified foot, Q66.81 — Congenital vertical talus deformity, right foot, Q66.82 — Congenital vertical talus deformity, left foot, +245 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Flat”; these codes share that main term but sit in a different category of the Tabular List.

E64.3 — Sequelae of rickets (foot, rachitic sequelae), M95.5 — Acquired deformity of pelvis (pelvis), O33.0 — Maternal care for disproportion due to deformity of maternal pelvic bones (pelvis, with disproportion), O65.0 — Obstructed labor due to deformed pelvis (pelvis, with disproportion, causing obstructed labor), Q67.8 — Other congenital deformities of chest (chest, congenital), Q74.2 — Other congenital malformations of lower limb(s), including pelvic girdle (pelvis, congenital), R45.89 — Other symptoms and signs involving emotional state (affect)

Contextual Map

Every relationship of Q66.50 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run Q66.50 with these 5 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

Nearest codes (40)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "Q66.50 — Congenital pes planus, unspecified foot." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/q66.50-congenital-pes-planus-unspecified-foot

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Congenital pes planus, unspecified foot

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Q66.50 in its code family, with their registry titles.

View all codes in the Q66 family