Key takeaways
- The FY 2027 ICD-10-CM code set applies to dates of service from October 1, 2026 through September 30, 2027. There is no grace period.
- CMS counts 190 new, 30 deleted and 4 revised codes.
- The biggest denial risk is codes that became non-billable headers, including I42.0, I42.8, I49.8, M72.2 and Z68.1. Claims using them will reject.
- Specialties with the most practical impact: cardiology, podiatry and orthopedics, OB/GYN, oncology and ENT.
- Update EHR favorites, superbills and claim scrubber rules, and check that payers' systems have loaded the new codes.
Every October 1, the ICD-10-CM diagnosis code set changes. Most years, the update is quiet for the average practice. FY 2027 is a little different, because several codes that many specialties use every day were expanded into more specific codes. When that happens, the old code becomes a non-billable header, and any claim that still uses it will be rejected.
The FY 2027 files apply to encounters and discharges from October 1, 2026 through September 30, 2027. CMS counts 190 new codes, 30 deleted codes and 4 revised codes. (Some sources report higher numbers because they include new non-billable headings in the total.)
Codes that are no longer billable
Start here. These are the changes most likely to generate rejections in the first weeks after October 1, usually because an EHR favorite list or a superbill was not updated.
| Former code (now a header) | Use instead |
|---|---|
| I42.0 Dilated cardiomyopathy | I42.00 unspecified, I42.01 familial-genetic, I42.09 other dilated cardiomyopathy |
| I42.8 Other cardiomyopathies | I42.81 arrhythmogenic cardiomyopathy, I42.89 other cardiomyopathies |
| I49.8 Other specified cardiac arrhythmias | I49.81 Brugada syndrome, I49.82 ventricular bigeminy, I49.89 other specified arrhythmias |
| M72.2 Plantar fascial fibromatosis | M72.20, M72.21, M72.22 (unspecified, right and left foot) |
| Z68.1 BMI 19.9 or less, adult | Z68.18 BMI 18.4 or less, Z68.19 BMI 18.5 to 19.9 |
What changed for each specialty
Cardiology
Cardiology has the most practical change this year. Dilated cardiomyopathy now requires a fifth character to show whether the condition is unspecified (I42.00), familial or genetic (I42.01) or another specified type (I42.09). Arrhythmogenic cardiomyopathy gets its own code (I42.81). Brugada syndrome (I49.81) and ventricular bigeminy (I49.82) are now separately coded instead of falling under I49.8, and a new code for catecholaminergic polymorphic ventricular tachycardia (I47.22) was added.
Documentation matters here. If the note says only "dilated cardiomyopathy," the coder must use the unspecified code. Where the etiology is known, ask providers to state it, both for coding accuracy and because more specific codes support medical necessity for devices and imaging. Our cardiology billing team builds these prompts into provider education.
Podiatry and orthopedics
Plantar fasciitis gets its own laterality-specific codes in a new subcategory: M67.A01 (right foot), M67.A02 (left foot) and M67.A09 (unspecified foot). Plantar fascial fibromatosis moves to M72.20 through M72.22. For practices that treat heel pain every day, this is a high-volume change. Update favorites so the right and left foot codes are easy to pick, and avoid defaulting to the unspecified code when laterality is documented. See our podiatry billing services for help with clean heel and foot claims.
Obstetrics and gynecology
A new set of codes under O31.4 describes continuing pregnancy after vanishing twin syndrome, with characters for trimester and fetus. There is also a new K6A category for pelvic diseases not elsewhere classified, including pelvic abscess codes that gynecology and general surgery will use. More on this in our OB/GYN billing page.
Oncology
New codes add specificity for secondary malignant neoplasms of the larynx (C78.31), pharynx (C78.32) and oral cavity (C79.83). Head and neck oncology, ENT and radiation oncology practices should update their problem lists.
ENT
Odontogenic sinusitis now has dedicated codes in the J34.83- range, by sinus location. These help separate dental-origin sinus disease from other chronic sinusitis for both clinical and coverage purposes.
Primary care, pediatrics and other changes
- Underweight BMI: Z68.1 splits into Z68.18 (BMI 18.4 or less) and Z68.19 (BMI 18.5 to 19.9) for adults.
- Pediatrics: a new code for hypertrophic pyloric stenosis in childhood (K31.B).
- Radiology: a new code for abnormal gadolinium level in blood (R78.72).
- Rheumatology: a new code for VEXAS syndrome (M04.3).
- Toxicology: new codes for toxic effects of specific organic solvents replace the deleted T52.8X family.
- Deleted: the S23.420 family for sternoclavicular joint sprain was removed, so check orthopedic and urgent care favorites.
How to prevent ICD-10 update denials
- Run a usage report. Pull every diagnosis code you billed in the last 12 months and compare it with the FY 2027 deleted and header lists. This takes an hour and shows exactly which providers and templates need updating.
- Fix the EHR first. Update favorites, order sets, problem-list mappings and superbill templates. Most errors come from saved shortcuts, not from coders.
- Add scrubber edits. Create a rule that stops any claim with a header code or a deleted code for dates of service on or after October 1, 2026.
- Brief providers on documentation. Laterality for plantar fasciitis and etiology for dilated cardiomyopathy are the two most common gaps this year.
- Watch October and November remittances. Some payers load updates late. If a valid new code is rejected, document it and contact the payer rather than switching to a less specific code.
Coding updates are one of the most common reasons denials spike in the fall. If you want a fast check, our medical coding team can audit a sample of your October claims against the FY 2027 code set. For the full picture of what is driving denials this year, see our 2026 claim denials playbook.
Sources
- CMS: ICD-10 code files (FY 2027)
- ACDIS: ICD-10-CM code set for fiscal year 2027 released
- HCCBuddy: FY 2027 ICD-10-CM code changes
This article is general information for healthcare practices, not legal or coding advice for a specific claim. Payer policies change often; confirm details with your MAC, payer contracts and the current CPT and ICD-10-CM code books.
RCM Expert Consultants Editorial Team
Written and reviewed by our certified coders, billing specialists and credentialing staff, who work US claims every day for practices across dozens of specialties.
