ICD-10-CM 2026 Updates: What Coders and Practices Need to Review

On October 1, 2026, the FY 2027 ICD-10-CM code set took effect with 190 new, 30 deleted and 4 revised diagnosis codes, as the Society of Interventional Radiology reported when CMS posted the files on June 5. Most claims in A/R, appeals and payer audits still carry 2026 dates of service. Those claims follow the ICD-10-CM 2026 updates, not the new code set.

The ICD-10-CM 2026 updates came in two releases. The FY 2026 code set started October 1, 2025, and the April 1, 2026 update changed instructional notes without adding a single code. Payers moved in the same window: UnitedHealthcare Medicare Advantage began enforcing Excludes1 edits on inpatient claims February 1, 2026 and on outpatient and professional claims March 1, 2026.

Quick answer: The ICD-10-CM 2026 updates cover dates of service from October 1, 2025 through September 30, 2026. The FY 2026 code set added 487 codes, revised 38 and deleted 28. The April 1, 2026 update added no codes but converted several Excludes1 notes to Excludes2 and changed the I16.1 note to “code also.” Dates of service from October 1, 2026 use the FY 2027 code set.

ICD-10-CM 2026 Update Timeline

The timeline below lists the 2026 ICD-10 news that changed codes or claim edits, in date order.

Source: CMS ICD-10 page; AHA Coding Clinic; CMS Transmittal R13490CP; UnitedHealthcare Medicare Advantage Reimbursement Policy Update Bulletin, January 2026; Society of Interventional Radiology.

Each date changes the codes or edits a claim must pass, so coders review every claim against the rules in force on its date of service.

What Changed in the FY 2026 ICD-10-CM Code Set?

The FY 2026 ICD-10-CM code set added 487 codes, revised 38 and deleted 28 for encounters and discharges from October 1, 2025, according to the AHA Coding Clinic. Every one of the 28 deleted codes was split into more specific child codes, so the old code no longer passes claim validation.

The table below lists 10 FY 2026 code families and the documentation each one needs.

Source: CMS 2026 ICD-10-CM Addendum; FY 2026 ICD-10-CM Official Guidelines for Coding and Reporting.

Each row adds a documentation element, so provider templates need the same update as the code list.

Which FY 2026 Codes Are No Longer Billable?

G35, R10.2, H01.8, E88.1 and E78.01 are among the codes that became parent categories on October 1, 2025, and none of them is valid on a claim. G35 now requires G35.A, G35.B0 to G35.B2, G35.C0 to G35.C2 or G35.D. R10.2 requires R10.20 to R10.24, and H01.8 requires one of nine eyelid inflammation codes from H01.81 to H01.8B. Other pain categories are covered in our guide to ICD-10-CM pain diagnosis codes.

Payer policies follow these splits on their own schedule. Blue Cross & Blue Shield of Rhode Island replaced E88.1 with E88.10 to E88.14 and E88.19 in its lipoprotein testing policy effective April 1, 2026, six months after the code change.

What Changed in the FY 2026 ICD-10-CM Coding Guidelines?

The FY 2026 ICD-10-CM Official Guidelines added rules for multiple sites, HIV sequencing and type 2 diabetes in remission, and they apply to every FY 2026 date of service. Five guideline changes affect daily code assignment:

• Commas in the Alphabetic Index (I.A.7): A comma’s meaning depends on context. It marks alternate wording, a modifier or an “and/or” choice.
• Other clinicians’ notes (I.B.14): Firearm injury intent joins BMI, pressure ulcer stage, social determinants of health and laterality as data a coder can take from a non-provider note.
• Multiple sites (I.B.20): “Multiple” means two or more sites. Coders follow the chapter guideline first, code each documented site separately and use a “multiple sites” code only when the sites are not specified.
• HIV (I.C.1.a): The revised section covers antiretroviral management. A patient with documented HIV disease on antiretrovirals gets B20, and an HIV-positive patient with no HIV disease gets Z21.
• Type 2 diabetes in remission (I.C.4.a.1.b): E11.A requires provider documentation of remission. The guideline states that “resolved” is not the same as remission and tells coders to query when the record is unclear.

These official coding guidelines for 2026 still govern any FY 2026 claim reworked after October 1, 2026.

What Changed in the April 1, 2026 ICD-10-CM Update?

The April 1, 2026 update added, deleted and revised no ICD-10-CM codes. It changed instructional notes in the Tabular List for encounters and discharges from April 1 through September 30, 2026.

The changes sit in the April 1, 2026 Addendum and the April 1, 2026 Code Tables, Tabular and Index ZIP files on the CMS ICD-10 page. CMS sent the update to Medicare contractors in Transmittal R13490CP, with an April 1 effective date and an April 6, 2026 implementation date. Four April 1, 2026 changes affect coding and claim edits:

• Excludes1 to Excludes2 conversions: Several code pairs that were blocked can now be reported together when both conditions are documented. Heartburn (R12) and dyspepsia NOS (R10.13) are one example.
• Hypertensive emergency (I16.1): The “use additional code” note for organ dysfunction became a “code also” note. Under Guideline I.A.17, a “code also” note gives no sequencing direction, so the reason for the encounter decides which code goes first.
• Updated guidelines: CMS and NCHS reissued the FY 2026 Official Guidelines as an April 1, 2026 version for April 1 to September 30, 2026, with narrative changes marked in bold.
• ICD-10-PCS: Hospitals received 80 new procedure codes and 2 deletions, with MS-DRG Grouper version 43.1.

A team that checked only for new codes on April 1 missed every one of these changes.

Why Do Excludes Note Changes Affect Payer Edits?

Excludes notes decide whether a claim edit accepts two diagnosis codes together, and payers enforce those notes in 2026. UnitedHealthcare Medicare Advantage began enforcing Excludes1 rules on inpatient claims February 1, 2026 and extended enforcement to outpatient and professional claims March 1, 2026, according to its January 2026 reimbursement policy bulletin. An edit table that still runs October 2025 notes blocks code pairs that became valid on April 1, 2026.

The guidelines also allow two codes under an Excludes1 note when the conditions are unrelated, and they tell coders to query the provider when the link is unclear (Guideline I.A.12.a). A provider statement that the conditions are separate supports the claim when a payer edit flags it.

What Changed in the ICD-10-CM Code Set on October 1, 2026?

The FY 2027 ICD-10-CM code set took effect October 1, 2026 with 190 new, 30 deleted and 4 revised codes, and it applies to encounters and discharges through September 30, 2027, according to the CMS ICD-10 page. The table below lists 12 FY 2027 changes that replace or expand codes used in 2026.

Source: CMS 2027 ICD-10-CM code files; Society of Interventional Radiology.

The FY 2027 Official Guidelines govern these codes for dates of service from October 1, 2026. Plantar fasciitis shows the pattern: M72.2 stopped being billable, and M67.A01, M67.A02 and M67.A09 now carry the laterality, as our plantar fasciitis ICD-10 code guide explains.

Which Codes Stopped Being Billable on October 1, 2026?

Thirty codes stopped being billable on October 1, 2026. Eight codes and code groups became parent categories: D69.1, I42.0, I42.8, I49.8, M72.2, M86.8X1 to M86.8X8, Z68.1 and Z87.890.

The sternoclavicular sprain codes S23.420A, S23.420D and S23.420S and the T52.8X- organic solvent codes were deleted, and T52.81-, T52.82- and T52.89- now report solvent toxicity.

Which ICD-10-CM Code Set Applies to a 2026 Claim?

The date of service decides the code set for outpatient claims, and the discharge date decides it for inpatient claims. The date the claim is sent does not change the code set. Use the table below to match each date range to its code files and guidelines.

Source: CMS ICD-10 page.

An inpatient stay admitted September 28, 2026 and discharged October 3, 2026 uses FY 2027 codes, because the discharge date falls in FY 2027.

Pro Tip: Keep the FY 2026 code tables active in the claim scrubber for corrected claims, appeals and late charges. M04.3 for VEXAS syndrome is valid on an October 1, 2026 visit and invalid on a September 30, 2026 visit, so the edit has to check the date of service, not the claim date.

Which Instructional Notes Should Coders Re-Check in 2026?

Coders should re-check five instructional notes in 2026: D63.0, E89.1, I5A, T45.A- and G35. Each one controls code order or code choice across two chapters, and the order is easy to reverse from memory. The table below shows each Tabular List note and the code order it requires.

Source: FY 2026 ICD-10-CM Tabular List; FY 2026 ICD-10-CM Official Guidelines, April 1, 2026 version.

Older cheat sheets still list E89.1 first for postpancreatectomy diabetes, because the order reversed on April 1, 2024. Anemia types outside D63.0 are listed in our ICD-10 code for anemia guide.

What Should Practices Update After Each ICD-10-CM Release?

Practices should update six items after every ICD-10-CM release: code files, pick lists, scrubber edits, provider templates, test claims and denial reports.

1. Load the release files by date. Load the CMS code tables and addendum into the EHR, practice management system and encoder, and keep prior versions active for older dates of service.
2. Remove parent codes from pick lists. Replace G35, R10.2, I42.0, I49.8 and Z68.1 in favorites, superbills and order sets with their child codes.
3. Update scrubber edit tables. Load the Excludes1 and Excludes2 notes from the April 1, 2026 Tabular List into your claim scrubbing rules, then add payer rules such as UnitedHealthcare’s Excludes1 edits.
4. Update provider templates. Add prompts for MS type, laterality, remission status and adult BMI range.
5. Run test claims on both sides of October 1. Send one September 2026 and one October 2026 date of service through the clearinghouse before live billing.
6. Track diagnosis denials by code set. Group diagnosis denials by date of service to find a scrubber or pick list that missed a release.

Repeating these six steps before each April 1 and October 1 keeps every claim matched to its code set. CPT codes change on a separate January 1 cycle, covered in our guide to CPT 2026 changes.

What Are the Most Common ICD-10-CM 2026 Coding Errors?

The table below lists seven errors tied to the ICD-10 2026 changes, what each one causes and how to fix it.

These denials often return as CARC 146 (diagnosis invalid for the date of service), CARC 16 (claim lacks information or has a billing error) or CARC 11 (diagnosis inconsistent with the procedure), explained in our guide to common denial codes in medical billing.

How Can iSolve RCM Help With ICD-10-CM Updates?

iSolve RCM updates diagnosis code mappings every April 1 and October 1, so each claim carries the ICD-10-CM code set that matches its date of service. Our certified medical coding team reviews remission status, laterality, MS type and sequencing notes before claims go out, and our medical billing audit catches code set and Excludes1 errors before payers do. When a diagnosis denial still comes back, our denial management team corrects and resubmits the claim. Services start at 2.99% of monthly collections.

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