B35.1 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

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Code lookupB35.1

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Mycoses (B35-B49)

B35.1

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Tinea unguium

A fungal infection of the nails (toenails or fingernails), also known as onychomycosis or nail fungus.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

N/A

—

Not risk-adjusted for this model/period.

Not mapped

ESRD/PACE

N/A

—

Not risk-adjusted for this model/period.

Not mapped

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

B35Dermatophytosis B35.1Tinea unguium

Inclusion Terms

Official

Dermatophytic onychia
Dermatophytosis of nail
Onychomycosis
Ringworm of nails

Excludes 2

Official

carrier or suspected carrier of infectious disease (Z22.-)Inherited from A00-B99, B35-B49
infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)Inherited from A00-B99, B35-B49
infectious and parasitic diseases specific to the perinatal period (P35-P39)Inherited from A00-B99, B35-B49
influenza and other acute respiratory infections (J00-J22)Inherited from A00-B99, B35-B49
hypersensitivity pneumonitis due to organic dust (J67.-)Inherited from A00-B99, B35-B49
mycosis fungoides (C84.0-)Inherited from A00-B99, B35-B49

Related Codes

Official

B35.0Tinea barbae and tinea capitis B35.2Tinea manuum B35.3Tinea pedis B35.4Tinea corporis B35.5Tinea imbricata

Includes

Official

diseases generally recognized as communicable or transmissibleInherited from A00-B99, B35
favusInherited from A00-B99, B35
infections due to species of Epidermophyton, Micro-sporum and TrichophytonInherited from A00-B99, B35
tinea, any type except those in B36.-Inherited from A00-B99, B35

Excludes 1

Official

certain localized infections - see body system-related chaptersInherited from A00-B99

Code First

Official

No Code First sequencing instructions are included in this display for B35.1. Check the code and parent instructions in the Code Book.

Use Additional

Official

code to identify resistance to antimicrobial drugs (Z16.-)Inherited from A00-B99

Code Also

Official

No Code Also instructions are included in this display for B35.1. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Document which nails are affected (fingernails vs. toenails) when available for clinical clarity

This condition is chronic and may require long-term treatment

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is B35.1 an HCC code?

No. B35.1 is a billable ICD-10-CM code with no mapping under the current CMS-HCC V28 community payment model, and none under the ESRD, Part D RxHCC, or HHS-HCC models.

Code: B35.1
Description: Tinea unguium
HCC (V28): No CMS-HCC V28 mapping
RAF reference coefficient: —
Billable: Yes
Payment year: 2026

Coder workflow notes

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What This Code Means

B35.1 is the ICD-10-CM diagnosis code for tinea unguium. A fungal infection of the nails (toenails or fingernails), also known as onychomycosis or nail fungus. B35.1 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering mycoses (b35-b49).

B35.1 is a billable ICD-10-CM code, but no current CMS-HCC V28 community payment mapping is shown, and none under the ESRD, Part D RxHCC, or HHS-HCC models. Do not assign risk adjustment value from this page when no source-backed mapping is shown; verify the applicable model and payment year.

Document which nails are affected (fingernails vs. toenails) when available for clinical clarity.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for B35.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document which nails are affected (fingernails vs. toenails) when available for clinical clarity
•This condition is chronic and may require long-term treatment