ICD-10-CM FY 2026 Code Updates: What Coders Need to Know Before October 1, 2025

The Centers for Medicare & Medicaid Services (CMS) has officially released the ICD-10-CM code updates for the 2026 fiscal year. Effective for discharges and encounters from October 1, 2025, through September 30, 2026, this release introduces 487 new diagnosis codes, 38 code revisions, and 28 code deletions. Coders, clinicians, and healthcare organizations should review these changes now to ensure timely compliance and optimal reimbursement.

Below is a breakdown of some of the most impactful updates across key clinical categories.

Digestive System & Abdominal Symptom Codes Get More Precise

FY 2026 introduces 16 new “R” codes designed to provide better specificity when reporting abdominal, pelvic, and perineal pain and tenderness. For instance, R10.2 – Pelvic and perineal pain has been converted into a parent code to support more granular reporting.

In addition, a newly created code, R11.16 – Cannabis hyperemesis syndrome, allows coders to document CHS— a condition marked by cyclic vomiting in chronic cannabis users. There are also five new codes for costovertebral angle tenderness and expanded codes for immunological serum findings (e.g., R76.89).

Expanded “Z” Codes Capture Social and Environmental Factors

Reflecting CMS’s emphasis on social determinants of health (SDoH), the FY 2026 update enhances the Z code family:

• Z59.86 becomes a parent code with new child codes related to financial insecurity.
• New Z77.3- series codes will help identify patient exposure to war or conflict zones.
• Food allergy codes become more granular: Z91.011 (Allergy to milk products) and Z91.012 (Allergy to eggs) are now parent codes with more detailed sub-options.

Oncology: New Diagnostic Detail for Breast Cancer and Genetic Risk

Significant additions are made to oncology-related coding:

• C50.A – Malignant inflammatory neoplasm of breast becomes a parent code with specific options for inflammatory breast cancer (IBC).
• D71.- expands to accommodate functional disorders of polymorphonuclear neutrophils.
• A new family of codes under Z15.06- now allows documentation of genetic susceptibility to malignant neoplasms of the digestive system, including colorectal cancers.

Emergency Department Coding Enhancements

Updates to Chapter 19 (Injury) support better Emergency Department documentation:

• New parent codes for contusions: S30.11- (abdominal wall), S30.12- (groin), and S30.13- (flank).
• Specificity is introduced for food-related anaphylaxis, such as T78.07- (reaction to dairy with baked milk tolerance) and T78.080- (reaction to egg with baked egg tolerance).

Neurology & Neurosurgery: Multiple Sclerosis and Genetic Disorders

Big news for neurology coders: G35 – Multiple sclerosis is now a parent code with new subcategories for MS subtypes like relapsing-remitting MS and primary progressive MS.

A newly introduced section (QA0.-) will capture neurodevelopmental disorders tied to genetic variants, including Usher syndrome and congenital malformations that previously lacked specific diagnosis codes.

Eye Disorders and Glaucoma Coding Additions

Ophthalmology coders should note:

• New entries under H01.8- for various types of eyelid inflammation.
• Expanded laterality options for thyroid orbitopathy (H05.83-) and neovascular secondary angle closure glaucoma (H40.84-).

Musculoskeletal Revisions Clarify Diagnoses

Chapter 13 brings a few but important changes:

• New code: M05.A – Abnormal rheumatoid factor and anti-citrullinated protein antibody with rheumatoid arthritis.
• Code M21.159 is revised to specify “hip.”
• Coders now have access to M24.076 for loose body in unspecified toe joint(s) and M61.129, revised to clarify it covers either upper arm in myositis ossificans progressiva.

Genitourinary System: Nephrotic Syndrome and Kidney Disease Coding

New subcategories under N00.B- and N04.B- allow coders to capture the type and cause of immune complex membranoproliferative glomerulonephritis (IC-MPGN), whether idiopathic or secondary.

Another notable addition is N07.B – Hereditary nephropathy associated with APOL1-mediated kidney disease (AMKD), offering more specificity for genetic kidney disorders.

New Codes for Fluoroquinolone Reactions

A new parent code, T36.A-, allows for detailed documentation of adverse events, underdosing, or poisoning due to fluoroquinolone antibiotics. This ensures better tracking of antimicrobial side effects and patient safety trends.

Don’t Miss the Complete CMS ICD-10-CM Code Set

These highlights represent only a portion of the updates. For a full breakdown, refer to CMS’s official FY 2026 ICD-10-CM release issued on June 6, 2025. Staying current is not just about compliance—it’s essential for reimbursement accuracy and minimizing denials.

Need Help Navigating These ICD-10-CM Changes?

Staying ahead of code changes is vital for avoiding revenue disruption. Our expert medical coding team is here to help your organization stay compliant, accurate, and profitable. Whether you need guidance implementing these new ICD-10-CM codes or a full-scale coding audit, our certified coders are ready to support you.

• Partner with us to improve coding accuracy
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