FY 2027 ICD-10-CM Updates: What Medical Practices Should Check to Prevent Claim Denials

FY 2027 ICD-10-CM Updates: What Medical Practices Should Check to Prevent Claim Denials

Every October, CMS and the CDC's National Center for Health Statistics release an updated ICD-10-CM code set, and every year a few practices find out about the changes only after a claim comes back denied. The FY 2027 ICD-10-CM updates took effect October 1, 2026, and are now in force, bringing 238 new code entries, a small set of description changes, and 21 deletions. Several of these changes sit in categories that primary care, orthopedic, cardiology, and OB-GYN practices bill often, which means most practices are already working with at least one affected code whether they have confirmed it yet or not.

This guide walks through what actually changed in the FY 2027 ICD-10-CM code set, when the new codes took effect, and what practices should check right now in their EHR, superbill, and coding workflow to keep claims moving cleanly under the updated set. The goal is practical: know what to look for, know where to look for it, and catch any gaps before they turn into a backlog of denials.

What Changed in the FY 2027 ICD-10-CM Code Set?

The FY 2027 ICD-10-CM update, published through CMS and CDC NCHS, includes 238 new code entries, made up of roughly 190 new billable codes and 48 new non-billable category headers that organize related codes underneath them. The update also includes a small number of description changes to retained codes, and 21 deletions.

Industry coding summaries built from the CMS addendum put the revised group at around 19 retained entries affected, split between two types of change. Fifteen previously billable codes were restructured into non-billable category headers, meaning the old code no longer stands alone and a more specific child code must be selected instead. Four codes kept their billable status but had their descriptions updated, including L02.232, L03.312, L03.322, and Z29.14. Because billing software vendors sometimes summarize this addendum slightly differently, practices should confirm the exact revised-code list against the official FY 2027 addendum file published on the CMS ICD-10-CM page rather than relying on any single secondary summary, including this one.

On the deletion side, 21 codes are being removed, 15 of them previously billable and 6 of them category headers. The largest cluster of deletions sits within the T52.8X family, codes used for toxic effects of other organic solvents, with 17 of the 21 deletions falling in or near that family. The remaining deletions include a small set of S23.420 sternoclavicular sprain codes. A deleted code does not automatically map one to one onto a single replacement, so practices that use the CMS conversion table should check each deleted code individually rather than assuming a direct swap.

A few specific changes are worth flagging because they touch common diagnoses across several specialties.

Plantar Fasciitis and Osteomyelitis Now Require Laterality

New codes under the M67.A plantar fasciitis and plantar fascial fibromatosis category, and the M86.8X osteomyelitis family, now require the provider to specify which side of the body is affected. A note that simply says "plantar fasciitis" without stating right, left, or bilateral will map to an unspecified code, which carries more denial risk than it used to under the prior code structure.

Cardiomyopathy Coding Gains More Specificity

Dilated cardiomyopathy, previously reported under the single code I42.0, is reported industry-wide as expanding into more specific subcodes under the FY 2027 update. Cardiology and internal medicine practices that bill this diagnosis regularly should confirm with their EHR vendor exactly how the old code maps forward and update any saved favorites or templates that still reference the prior single code.

OB-GYN Sees the Largest Single Expansion

Ectopic pregnancy and related obstetric codes account for one of the largest blocks of new entries in the FY 2027 set, with a new O31.4 category and a substantial number of related new codes. Practices billing obstetric care should review this section closely, since a sizable share of the chapter's new codes sits here.

New Z Codes for History and Risk Factors

The update adds several new Z codes covering history and exposure information, including codes related to military exposure history, history of Clostridioides difficile infection, and expanded body mass index categories under Z68.18 and Z68.19. These codes do not themselves drive reimbursement the way a primary diagnosis does, but they can strengthen the clinical picture supporting other billed services, particularly for surgical risk assessment, fracture care, and chronic disease management documentation.

Other new codes touch postprocedural hypoglycemia, hepatic fibrosis (K74.0A), odontogenic sinusitis (J34.83), and specific platelet disorder codes (D69.11 and D69.19). None of these are high-volume for every practice, but any practice that bills them regularly should check whether its current shorthand code still applies.

When Do the New ICD-10-CM Codes Take Effect?

The FY 2027 ICD-10-CM code set applies to patient encounters and discharges occurring from October 1, 2026 through September 30, 2027. There is no grace period. For outpatient and professional claims, the code set in effect is determined by the date of service. For inpatient claims, it is determined by the date of discharge.

This means a claim for a visit on September 30, 2026 should still use the FY 2026 code set, while a claim for a visit on October 1, 2026 must use the FY 2027 set, even if both claims are submitted to the payer on the same day. Practices sometimes run into trouble here when a batch of claims for late-September visits gets held and submitted in early October using the wrong year's codes, or the reverse, where an October visit gets coded using a saved note template still populated with FY 2026 codes.

Because deleted and revised codes stop being valid for dates of service on or after October 1, 2026, any claim submitted with an outdated code for a post-effective-date encounter is at risk of rejection or denial, regardless of how accurate the underlying diagnosis was.

How Outdated Diagnosis Codes Can Affect Claims

Using a deleted, outdated, or no-longer-billable ICD-10-CM code doesn't just create an administrative inconvenience. It directly affects whether and how a claim gets paid.

A claim submitted with a deleted code is typically rejected outright by the payer's front-end claim edits before it ever reaches adjudication, which means the claim has to be corrected and resubmitted from scratch. A claim submitted with a code that was restructured from billable to a category header faces the same problem, since the payer's system no longer recognizes that code as a valid, billable diagnosis on its own.

Medical necessity is affected as well. When a new code family adds required specificity, such as laterality for plantar fasciitis or osteomyelitis, continuing to document and bill at the old, less specific level can push the claim toward an unspecified code. Payers often apply more scrutiny to unspecified codes, and in some cases, local coverage determinations and medical policy require a specific diagnosis code to support medical necessity for a given service or supply.

There's also a downstream effect on prior authorization. If a practice's prior authorization request used a diagnosis code that gets deleted or restructured before the authorized service is actually performed, the diagnosis on the final claim may no longer match what was authorized, which can trigger a payer review or a reimbursement delay even when the clinical care was entirely appropriate.

None of this requires a practice to get everything perfect on day one. It does mean that the cost of an outdated code shows up as claim rework, extra staff time, and delayed cash flow, all of which are preventable with a reasonable amount of preparation before the effective date.

What Medical Practices Should Review in Their EHR and Superbill

The FY 2027 changes only create a problem if a practice's own tools still point to the old codes now that October 1 has passed. A focused review of a few specific places in the EHR and billing workflow catches most of the risk, even for a practice that is only getting to this check a week or two after the effective date.

Run a Diagnosis Frequency Report

Pull a report of the diagnosis codes billed most often over the past 12 months and check that list against the FY 2027 deleted and revised code lists. This single step identifies most of a practice's real exposure, since most practices bill from a relatively short list of frequently used codes even though the full ICD-10-CM set contains tens of thousands of entries.

Check Saved Favorites, Problem Lists, and Templates

EHR systems commonly store frequently used diagnosis codes in favorites lists, quick-pick menus, smart phrases, and visit templates. Any of these that reference a deleted code, or a code that has been restructured into a non-billable header, needs to be updated before providers start documenting October encounters.

Update the Superbill and Encounter Forms

Paper or electronic superbills that list diagnosis codes by name or shorthand should be checked line by line against the FY 2027 addendum, particularly for any specialty-specific codes identified earlier, such as plantar fasciitis, osteomyelitis, or cardiomyopathy codes. If this check hasn't happened yet, any encounter already billed since October 1 using an old superbill line is worth a second look.

Confirm the Vendor Actually Pushed the Update

Most EHR and practice management vendors push the updated code set through a scheduled release, but the exact timing varies by vendor, and not every practice confirms the update actually landed. Checking directly with the vendor, rather than assuming the FY 2027 set is live simply because the calendar has passed October 1, closes any gap where staff are still coding against an outdated code set without realizing it.

Review Clearinghouse and Payer Edits

Clearinghouses and payers update their own claim-edit logic to reflect the new code set, but the timing of those updates doesn't always align perfectly with a practice's own go-live date. Confirming with the clearinghouse that edits are updated, and checking whether any payer-specific coverage policies reference the codes a practice bills regularly, reduces the chance of a claim getting caught between two mismatched systems.

How to Update Coding Workflows Before Submitting Claims

Beyond the EHR itself, the coding workflow around claim submission benefits from a few concrete steps before the effective date.

Build a simple crosswalk for any deleted or restructured code the practice uses regularly, using the CMS conversion table as the starting reference point, and confirm the mapping makes clinical sense for the practice's own patient population rather than applying it automatically. A conversion table entry shows a statistical or structural relationship between an old and new code, but the provider still has to confirm the new code accurately reflects the documented diagnosis.

Schedule coder and provider training on the specific changes most relevant to the practice's specialty, particularly any new laterality or specificity requirements. A short, targeted training session on the two or three code families a practice actually bills tends to be more effective than a general overview of all 238 changes, and this training is just as useful now, weeks into the new fiscal year, as it would have been in September.

Make sure coders are referencing the FY 2027 ICD-10-CM Official Guidelines for Coding and Reporting, published alongside the code set, rather than an outdated copy of the prior year's version. The guidelines sometimes clarify how a new or revised code should be sequenced or combined with other diagnoses, and working from the wrong year's guidelines can lead to a technically valid code used the wrong way.

Finally, run a quick audit of recent claims coded since October 1 against the updated set, checking a sample of real encounters rather than assuming the transition went smoothly. This catches configuration issues, such as a favorites list that didn't update correctly, before they turn into a larger wave of denials.

Documentation and Medical Necessity Checks

Code changes only work if clinical documentation supports the level of specificity the new codes require. A few documentation habits matter more under the FY 2027 update than they did before.

Where a new code family requires laterality, such as plantar fasciitis or osteomyelitis, the clinical note needs to state right, left, or bilateral clearly, rather than leaving it to be inferred from context elsewhere in the chart. A coder generally cannot assign a laterality code based on an assumption, even a reasonable one, without clear documentation to support it.

Where a code has been restructured from a single billable entry into a category with multiple child codes, the documentation needs to contain enough clinical detail to select the correct child code, not just the general diagnosis. This is the same principle that applies across ICD-10-CM more broadly: the documentation should drive the code, not the other way around.

Providers should also confirm that any diagnosis carried forward in a note from a prior visit, through copy-forward or templated text, is still clinically accurate and current, particularly for a diagnosis that was coded under the FY 2026 set and may now need to be updated to reflect a more specific FY 2027 code.

For services tied to local coverage determinations or specific medical necessity criteria, it's worth double-checking whether the payer's covered diagnosis list has been updated to include the new, more specific FY 2027 codes. A payer policy that hasn't yet been updated to recognize a new code can create a temporary mismatch, even when the practice has coded correctly under the new set.

How Billing Teams Can Monitor Coding-Related Denials

Even with careful preparation, some denials tied to the FY 2027 transition are likely in the first few weeks after the effective date. The practices that recover fastest are the ones watching for a specific pattern rather than treating every denial as a one-off.

Set up a denial review specifically for claims with dates of service on or after October 1, 2026, and separate these from the practice's general denial workflow for the first few weeks of the new fiscal year. This makes it easier to spot a pattern, such as a particular deleted code still being used in a saved template, before it affects a large batch of claims.

Track denial reason codes alongside the diagnosis codes on the claim, so that a denial tied to an invalid or deleted diagnosis code is easy to distinguish from a denial tied to an unrelated issue, such as eligibility or authorization. This distinction matters because the fix for a coding-related denial is different from the fix for other denial types, and lumping them together slows down root cause analysis.

When a pattern does show up, correct it at the source rather than only on the individual claim. If a particular favorites list entry or smart phrase is generating a deleted code repeatedly, fixing that one setting prevents the same denial from recurring across every subsequent claim that uses it.

Finally, keep a short internal log of which FY 2027 changes actually affected the practice's claims in the real world, separate from the general list of changes published by CMS. This practical, practice-specific list becomes a useful reference heading into the next year's update cycle.

Frequently Asked Questions

What is new in the FY 2027 ICD-10-CM updates?

The FY 2027 ICD-10-CM update adds 238 new code entries, including new billable codes and category headers, along with a small number of description changes to retained codes and 21 deletions. Notable changes include new laterality requirements for plantar fasciitis and osteomyelitis codes, expanded cardiomyopathy coding, a large block of new ectopic pregnancy codes, and new Z codes for exposure history and body mass index.

When do the new ICD-10-CM codes take effect?

The FY 2027 ICD-10-CM code set took effect October 1, 2026, and is now in force through September 30, 2027. Outpatient and professional claims use the code set in effect on the date of service, while inpatient claims use the code set in effect on the date of discharge, so any claim for an encounter on or after October 1 should already reflect the new set.

What happens if a practice bills a deleted ICD-10-CM code?

A claim billed with a deleted ICD-10-CM code for a date of service on or after the code's effective deletion date is typically rejected by the payer's claim edits and has to be corrected and resubmitted. This creates claim rework and can delay reimbursement.

How can practices update EHR diagnosis codes for 2027?

Practices should confirm their EHR vendor actually pushed the update, run a diagnosis frequency report against the FY 2027 deleted and revised code lists, and review saved favorites lists, smart phrases, templates, and superbills for any codes affected by the update. Since the updated set has already been in effect since October 1, 2026, this is worth checking now rather than waiting, so any claims coded since then can be corrected quickly if needed.

Why do unspecified ICD-10-CM codes increase denial risk?

When documentation doesn't support the level of specificity a code family requires, such as laterality, the claim defaults to a less specific or unspecified code. Payers often apply closer review to unspecified codes, and some coverage policies require a specific diagnosis code to establish medical necessity, which increases the chance of a denial or documentation request.

Do ICD-10-CM code changes affect prior authorization?

Yes. If a prior authorization request used a diagnosis code that is later deleted or restructured before the authorized service is performed, the diagnosis on the final claim may no longer match the authorization on file, which can trigger a payer review or delay reimbursement even when the underlying clinical care was appropriate.

Conclusion

The FY 2027 ICD-10-CM update is not a sweeping overhaul, but it touches enough high-volume categories, including plantar fasciitis, osteomyelitis, cardiomyopathy, obstetric care, and several commonly used Z codes, that most practices have at least a few affected codes somewhere in their regular billing. With the new set already in effect since October 1, the practices avoiding a bump in denials this fall are the ones checking their frequently billed codes against the update now, confirming their EHR vendor actually pushed the change live, and training providers on the handful of changes that apply to their specialty, rather than waiting to find out through a stack of denied claims.

Edge RCM CTA

Coding updates like this one tend to surface as denials weeks after they actually happen, once a practice notices a pattern in its aging report rather than catching the root cause at the source. Edge RCM, based in Reisterstown, works with practices to review diagnosis code usage ahead of annual ICD-10-CM updates, track denial patterns by root cause, and correct the EHR and workflow issues that keep generating the same denial. Whether your practice needs a one-time readiness check before October 1 or ongoing denial monitoring through the transition period, Edge RCM can help keep coding updates from turning into a backlog of rework.