The fiscal year (FY) 2026 ICD-10-CM update, effective October 1, 2025, introduces 487 new diagnosis codes, 38 revisions, and 28 deletions. These changes reflect an ongoing effort to enhance coding specificity, improve clinical documentation, and align code structure with emerging healthcare trends and treatments.
Below is a chapter-by-chapter overview of the most impactful additions and updates, along with revisions.
Chapter Highlights
Chapter 1: Certain Infectious and Parasitic Diseases
- New codes for Demodex mite infestation, with corresponding blepharitis codes
- Guideline update: Enhanced clarification for HIV sequencing
Chapter 2: Neoplasms
- Added codes for inflammatory breast cancer, improving classification of aggressive malignancies
- Minor guidance updates for antineoplastic treatment coding
Chapter 3: Blood and Immune Disorders
- New codes for leukocyte adhesion deficiency, a rare genetic disorder impacting immune function
Chapter 4: Endocrine, Nutritional, and
Metabolic Diseases
- Introduction of a code for type 2 diabetes in remission
- New codes to indicate distinct types of nutritional and metabolic disorders
- Guideline revision: Clear criteria for coding remission status, enhancing risk adjustment accuracy
Chapter 6: Nervous System Disorders
- Added codes for primary progressive apraxia of speech, multiple sclerosis subtypes, and muscular dystrophy variants
Chapter 7: Eye and Adnexa
- Expansion of blepharitis codes, including Demodex-related diagnoses
- New codes for thyroid eye disease and neovascular glaucoma
Chapter 9: Circulatory System
- 4 new codes for Fontan circulation
- Guideline revision: Clarifies sequencing for hypertension with heart disease and chronic kidney disease
Chapter 12: Skin and Subcutaneous Tissue
- Chapter 12 features one of the most substantial updates, introducing >100 new codes for non-pressure chronic ulcers, now classified by anatomical site and severity
Chapter 13: Musculoskeletal System and Connective Tissue
- Additional code for abnormal rheumatoid factor
- New guidance on documenting multiple anatomical sites and applying chapter-specific rules
Chapter 14: Genitourinary System
- New codes for APOL1-mediated kidney disease, as well as genetic susceptibility and family history indicators
Chapter 17: Congenital Malformations and Chromosomal Abnormalities
- 23 new codes for genetic syndromes and neurodevelopmental disorders tied to specific pathogenic variants
- A new subsection for neurodevelopmental coding
Chapter 18: Symptoms, Signs, and Abnormal Clinical Findings
- New codes for:
- Flank pain
- Cannabis hyperemesis syndrome
- Immunologic abnormalities (eg, abnormal serum findings)
Chapter 19: Injury, Poisoning, and Other Consequences of External Causes
- 213 new codes, including:
- Specific flank injuries (eg, contusions, lacerations)
- New poisonings (eg, fluoroquinolones, xylazine)
- Blast injuries and anaphylaxis from specific triggers
Chapter 20: External Causes of Morbidity
- Expanded external cause codes for:
- Fishing hook injuries
- Splitting wood
- Blast overpressure from military or war-related events
Chapter 21: Factors Influencing Health Status and Contact With Health Services
- 26 new codes, including:
- Prophylactic salpingectomy
- DES exposure
- Social determinants of health, such as utility insecurity, food and housing instability, and exposure to adverse environmental conditions
Key Guideline Revisions
In addition to code-level updates, several critical revisions to the ICD-10-CM Official Guidelines for Coding and Reporting were released:
- HIV: The FY2026 ICD-10-CM guidelines include significant changes to HIV coding, particularly on how to sequence codes when HIV-related conditions or comorbidities are present. These changes clarify when to use code B20 (HIV disease) and code Z21 (asymptomatic HIV infection status)
- Type 2 diabetes in remission: A new code, E11.A, type 2 diabetes mellitus without complications in remission, is introduced and assigned based on provider documentation that diabetes mellitus is in remission
- Multiple anatomical sites: Coders must follow chapter-specific instructions when dealing with conditions affecting multiple body sites. The classification defines “multiple” as involving ≥2 sites. In the absence of chapter-specific guidelines, assign codes describing specified sites individually when documented. When the specified site(s) are not documented, assign the appropriate code for “multiple sites”
- Hypertension with CKD and heart disease: The codes in category I13, hypertensive heart and chronic kidney disease (CKD), are combination codes that include hypertension, heart disease, and CKD. Improved sequencing guidance ensures correct code assignment and claim accuracy
- Body mass index: The FY2026 ICD-10-CM guidelines indicate body mass index (BMI) codes should be assigned only when there is an associated, reportable diagnosis, such as obesity or anorexia, documented by the patient’s provider. Also, when the documentation reflects fluctuating BMI values during the current encounter for an associated reportable condition, assign a code for the most severe value.
Conclusion
The FY2026 ICD-10-CM update brings some of the most comprehensive changes in recent years.
By starting early and prioritizing education and system readiness, providers, coders, and revenue cycle teams can reduce claim denials, optimize reimbursement, and ensure continued compliance across all care settings ahead of the October 1, 2025, implementation date.1,2
References
- Centers for Medicare & Medicaid Services, and National Center for Health Statistics. FY 2026 ICD 10 CM official guidelines for coding and reporting – Updated October 1, 2025. October 1, 2025-September 30, 2026. Accessed August 14, 2025. www.cms.gov/files/document/fy-2026-icd-10-cm-coding-guidelines.pdf
- Centers for Disease Control and Prevention, National Center for Health Statistics. ICD-10-CM October 2025 guidelines. 2025. Accessed August 14, 2025. ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Publications/ICD10CM/2026/ICD-10-CM-October-2025-Guidelines.pdf
