October 1 has come and gone, and if your billing team has been quiet this month, good. If it hasn’t, you probably already know why. A cardiology claim bounces because the template still carries I42.0. A podiatry note says “plantar fasciitis” and nobody is sure which of three new codes applies. That’s the FY 2027 ICD-10-CM update doing what annual updates do: not a huge release, but a pointed one.

This guide walks through what actually changed, where claims are most likely to fail, and what a Texas practice can do this week to stop the bleeding. We’ve cross-checked the numbers against the CMS and CDC files and the FY 2027 Official Guidelines for Coding and Reporting, because the figures floating around online don’t always agree (more on that below).

What Is the ICD-10-CM Update for 2027 (FY 2027)?

The ICD-10-CM update for 2027 is the yearly revision of the diagnosis code set used on every U.S. claim. The CDC’s National Center for Health Statistics maintains it, and CMS publishes the files. The FY 2027 version took effect October 1, 2026, covers encounters and discharges through September 30, 2027, adds 190 new billable codes, takes 30 codes out of billable use, and revises four code descriptions.

Key dates to keep straight

• June 2026: CMS and CDC posted the FY 2027 code files, tabular list, index and addenda.
• October 1, 2026: The code set takes effect for dates of service and discharges on or after this date.
• October 5, 2026: The implementation date CMS gave Medicare contractors for loading the updated ICD-10-CM files.
• January 4, 2027: CMS’s separate maintenance update to ICD-10 coding in National Coverage Determinations is scheduled to be implemented. It’s easy to miss, and it matters if you bill services with NCD diagnosis lists.
• September 30, 2027: The last day the FY 2027 code set applies.

Why it’s called “2027” when it started in 2026

CMS names the code set after the federal fiscal year, which begins October 1. So the set that went live in October 2026 is FY 2027. The FY 2027 Official Guidelines run on the same schedule, and adherence to them is required under HIPAA, not just recommended.

ICD-10-CM 2027 Changes at a Glance: New, Revised and Deleted Codes

Change	Count	What it means
New entries in the CMS order file	238	Every addition, including headers
Of those, non-billable headers	48	Category or subcategory levels that need more characters
New billable codes	190	What you can actually put on a claim
Revised code descriptions	4	Same code, new wording
Entries removed from the file	21	15 billable codes plus 6 headings
Retained codes that became headers	15	Still in the book, no longer billable
Billable codes lost in total	30	15 deleted plus 15 demoted to headers
Total billable codes in FY 2027	74,879	A net gain of 160

Why you’ll see 238, 190, 30 and 21, and why none of them is wrong

Search for the FY 2027 numbers and you’ll find some articles saying 238 new codes and 21 deletions, others saying 190 and 30. It looks like a contradiction. It isn’t.

• 238 minus 48 equals 190. The bigger number counts headers. The smaller one counts only codes you can bill.
• 21 removed plus 15 demoted does not equal 30. Of the 21 removed entries, only 15 were billable; the other 6 were headings. Add the 15 billable codes that survived as headers and you get 30 codes that stopped being billable.
• 190 minus 30 equals 160, which is exactly the net growth in billable codes.

If you’re training staff, use the billable numbers. They’re the ones that decide whether a claim goes through.

Where the new codes landed

Three chapters carry most of the weight. Injury and poisoning added 60 billable codes, pregnancy and childbirth added 44, and musculoskeletal added 31. That’s 135 of the 190, or about 71 percent. If your practice sees OB patients, orthopedic or podiatric problems, or toxicology cases, this update is bigger for you than the headline suggests.

Key New ICD-10-CM Codes for 2027 by Specialty

Obstetrics

Obstetrics gets the most detailed treatment this year, mostly in ectopic pregnancy and vanishing twin coding.

• Interstitial ectopic pregnancy: O00.12- (without intrauterine pregnancy) and O00.13- (with), each split into right, left and unspecified.
• Cesarean scar ectopic pregnancy: O00.3-, with and without an intrauterine pregnancy.
• Cervical ectopic pregnancy: O00.4-, same split.
• Cornual ectopic pregnancy: O00.5-, with right, left and unspecified options.
• Continuing pregnancy after vanishing twin syndrome: O31.4-, by trimester, with a seventh character identifying the fetus.

The Official Guidelines still tell coders to assign trimester from the provider’s documented weeks of gestation, and to use seventh character “0” for single gestations or when the fetus can’t be determined. Vanishing twin cases are exactly where that fetus character stops being a formality.

Cardiology

Cardiology sees the change most coders will feel first.

• Dilated cardiomyopathy is no longer one code. I42.0 is now a header; you choose I42.00 (unspecified), I42.01 (familial-genetic) or I42.09 (other).
• Arrhythmogenic cardiomyopathy gets I42.81, with I42.89 for other cardiomyopathies not elsewhere classified. I42.8 is now a header.
• Named arrhythmias get their own codes: I47.22 (catecholaminergic polymorphic ventricular tachycardia), I49.81 (Brugada syndrome), I49.82 (ventricular bigeminy) and I49.89 (other specified arrhythmias). I49.8 is now a header.

One thing to remember: code assignment rests on the provider’s diagnostic statement. If the note says “dilated cardiomyopathy” and nothing about a familial or genetic cause, I42.00 is the honest answer, not a guess at I42.01. The guidelines are clear that an unspecified code is correct when the record doesn’t support more.

Orthopedics and Podiatry

• Plantar fasciitis finally has its own home: M67.A01 (right foot), M67.A02 (left foot) and M67.A09 (unspecified foot). Many practices have been reporting it under M72.2, which is now a header.
• Plantar fascial fibromatosis moves to M72.20 (unspecified foot), M72.21 (right) and M72.22 (left).
• Other osteomyelitis (M86.8X-) now carries site and side. The old six-character codes M86.8X1 through M86.8X8 are headers; the billable codes run to seven characters, such as M86.8X11 (right shoulder) or M86.8X72 (left ankle and foot).
• VEXAS syndrome gets M04.3, a first for rheumatology.

On laterality, the guidelines say that when there’s no bilateral code and the condition is bilateral, you report both the left and the right. There is no bilateral plantar fasciitis code, so a patient with heel pain in both feet needs M67.A01 and M67.A02. Unspecified side should be rare, and side can be pulled from other clinicians’ documentation if the provider didn’t state it.

ENT and Dental

• Odontogenic sinusitis (sinusitis that starts from a dental source) now has subcategory J34.83-, with a sixth character for the sinus: J34.830 maxillary, J34.831 ethmoid, J34.832 frontal, J34.833 sphenoid, J34.839 unspecified.
• Pulmonary mycetoma gets J4B, a new category.

This is a good example of a code that depends on the clinical note doing its job. “Sinusitis” alone won’t get you here. The provider has to document the dental origin and which sinus is involved.

Oncology

• Secondary malignancy sites: C78.31 (larynx), C78.32 (pharynx) and C79.83 (oral cavity).
• Inherited cancer syndromes get a new category, QA1, which the guidelines now list as part of Chapter 17 (Q00-QA1): Lynch syndrome (QA1.71), familial cancer syndrome with pathogenic BRCA1 mutation (QA1.790), BRCA2 mutation (QA1.791) and Li-Fraumeni syndrome (QA1.792).
• Loeys-Dietz syndrome gets Q87.A.

Sequencing hasn’t changed. When treatment is directed only at a metastatic site, the secondary neoplasm is first-listed and the primary goes second.

Endocrine and Bariatric

Two new billable codes address hypoglycemia after procedures: E89.830 (post bariatric hypoglycemia) and E89.838 (other postprocedural hypoglycemia), under a new E89.83 header. For bariatric programs this is a long-awaited way to track a recognized complication.

The catch is documentation. The guidelines say complication coding depends on the provider documenting the relationship between the condition and the procedure. “Low glucose” after a gastric bypass isn’t enough on its own.

Z Codes

• Low BMI: Z68.18 (18.4 or less, adult) and Z68.19 (18.5 to 19.9, adult). Z68.1 is now a header.
• History of C. difficile: Z86.17.
• Exposure history: gadolinium (Z77.013), burn pits (Z77.32), Agent Orange (Z77.33) and blast overpressure (Z77.40 through Z77.49).
• Gender-related history: Z87.8901 through Z87.8904 and Z87.8909, plus Z87.893 for detransition and F64.A for gender identity disorder in remission.

BMI rules haven’t moved. A BMI code needs a provider-documented diagnosis such as underweight or malnutrition, it can only be a secondary code, and it isn’t assigned during pregnancy. A dietitian or nurse can supply the number, but the provider has to document the diagnosis.

Other areas worth a look

• Gastroenterology: K74.0A for moderate (stage F2) hepatic fibrosis, K76.83 for intestinal failure-associated liver disease, and a new K6A category for pelvic abscess.
• Toxicology: new toxic-effect codes for alkenes (T52.81-), cycloparaffins (T52.82-), other organic solvents (T52.89-), hexamethylene diisocyanate (T59.82-) and medetomidine (T65.85-).
• Hematology: D69.11 (Glanzmann thrombasthenia) and D69.19 (other qualitative platelet defects).
• Skin and breast: L02.237 (carbuncle of flank) and N99.860 and N99.861 for postprocedural nipple ischemia and necrosis.

Which Codes Were Deleted or Restructured in FY 2027?

New codes get the attention. Deleted and demoted ones cause the rejections. Here are the ones most likely to be sitting in your templates.

Old code	What happened	Where to look now
I42.0	Became a header	I42.00, I42.01, I42.09
I42.8	Became a header	I42.81, I42.89
I49.8	Became a header	I49.81, I49.82, I49.89
M72.2	Became a header	M72.20, M72.21, M72.22
M86.8X1 to M86.8X8	Became headers	Seven-character M86.8X codes by site and side
D69.1	Became a header	D69.11, D69.19
Z68.1	Became a header	Z68.18, Z68.19
Z87.890	Became a header	The new Z87.890- gender-history codes
S23.420 (A, D, S)	Deleted	See note below
T52.8X (all intents and 7th characters)	Deleted	T52.81-, T52.82-, T52.89-

The sternoclavicular sprain codes deserve a careful word. S23.420A, S23.420D and S23.420S are gone, and in the CMS addition list we reviewed there’s no obvious one-to-one successor. Don’t assume a replacement. Go through the Alphabetic Index and the CMS conversion table, and query the provider if the documentation doesn’t point clearly to a new code.

The same warning applies across the board. A removed code doesn’t always have a single successor, and the right replacement is the one the record actually supports.

ICD-10-PCS 2027 Changes (A Quick Note for Facility and Hospital Billing)

If you bill for a professional practice, PCS probably isn’t on your claims; it’s used for inpatient hospital procedures. But if you work with a facility, here’s the short version.

• 101 new codes, 3 revised and 38 deleted, bringing the code set to 79,256 codes.
• 50 of the new codes sit in 13 new technology tables, including a new XEZ table for other procedures using new technologies on physiological systems and anatomical regions.
• All 38 deletions are in new technology tables, which fits how those codes get retired or moved once a technology matures.
• Examples: new body-part values in table 028 for division of the aortic and mitral valves, a new qualifier in table 5A1 for a selective cytopheretic device, and a new table for other imaging procedures involving the eye.
• Guidelines: CMS made no significant changes to the PCS guidelines this year.

On the diagnosis side, a published analysis of the IPPS tables flags 3 of the 190 new codes as MCCs and 56 as CCs, so hospital CDI teams should check where those fall in their top DRGs.

How the 2027 ICD-10-CM Update Affects Claims, Denials and Reimbursement

New diagnosis codes don’t carry payment rates the way CPT codes do. What they change is whether a claim is accepted and whether the diagnosis supports medical necessity. That’s a quieter kind of financial impact, but it adds up.

Where claims actually fail

• Date of service decides the code set. A visit on September 30 uses FY 2026 codes. A visit on October 1 or later uses FY 2027 codes. It doesn’t matter when you submit the claim.
• Invalid or non-billable codes get rejected, sometimes at your clearinghouse and sometimes at the payer. A header like I42.0 on an October claim is an invalid code.
• Medical necessity edits lag behind the code set. Payers and Medicare contractors have to add new codes to their coverage lists, and for a while a perfectly accurate new code can fail an edit that was never updated.
• Medicare contractors load files on their own timeline. CMS gave October 5 as the implementation date, so claims with early-October dates of service may behave oddly until systems catch up.

Reimbursement, indirectly but for real

• Rejected claims that nobody catches turn into aged A/R and, eventually, timely filing losses.
• Downcoding to an unspecified code to “make it go through” can undercut medical necessity or risk-adjustment capture.
• Each rework costs staff time. Even a small number of repeat rejections on a high-volume code adds up over a quarter.

Documentation and Specificity Requirements for 2027 Codes

Most of this update asks the same thing of your providers: say it more precisely. Coders can only assign what the note supports, and the guidelines don’t let them guess to reach a more specific code.

Condition	What the note needs to say
Plantar fasciitis	Which foot. Both feet means two codes
Other osteomyelitis	The bone site and the side
Dilated cardiomyopathy	Whether it’s familial-genetic, another cause, or not specified
Odontogenic sinusitis	Dental origin and the specific sinus
Ectopic pregnancy	Location, side where applicable, and whether an intrauterine pregnancy is present
Vanishing twin pregnancy	Trimester and which fetus, when it applies
Hepatic fibrosis	The stage (moderate or F2 for K74.0A)
Postprocedural hypoglycemia	The procedure, and the provider’s link between the two
Toxic effects	The substance, the intent, and the encounter phase (A, D or S)
Low BMI	The number, plus a provider-documented diagnosis
Secondary malignancy	The specific site (larynx, pharynx or oral cavity)

Two guideline reminders worth pinning to the wall. First, a code is invalid if it’s missing characters, including a seventh character, and a placeholder X fills any empty spot before it. Second, in the outpatient setting you don’t code diagnoses documented as “probable,” “suspected” or “rule out.” A note that says “suspected familial cardiomyopathy” doesn’t earn I42.01 in a clinic visit; it earns the symptom or the confirmed condition.

And when intent isn’t stated on a toxic-effect case, the guidelines say to code it as accidental unless the record specifically says the intent can’t be determined.

How the 2027 Code Changes Affect Risk Adjustment (HCC) and Quality Reporting

Here’s the honest answer on HCCs: nobody can tell you yet.

CMS-HCC V28 has been fully phased in since payment year 2026. CMS has published the payment year 2027 initial ICD-10 mappings, but they were released before the FY 2027 codes were finalized, so the new codes aren’t in them. CMS normally assigns new codes to categories in its mid-year and final mapping updates. Until that happens, any article telling you a new code “is an HCC” is guessing, and you shouldn’t build workflows on a guess.

What you can do now:

• Audit anything keyed to I42.0, I42.8 or I49.8. Lookup tables, pick lists, problem-list mappings and audit rules that reference those codes now point at headers.
• Capture the specificity anyway. Documenting cardiomyopathy type or arrhythmia type properly costs nothing and positions you for whatever CMS decides.
• Keep your support standard. If your team uses MEAT (monitor, evaluate, assess, treat) to validate diagnoses, apply it to the new codes the same way.
• Watch your quality measures. Measure value sets and code lists tend to trail the code set. If a quality report suddenly looks off in the new fiscal year, check whether a new code is missing from the list before assuming performance dropped.

ICD-10-CM 2027 Update Checklist for Medical Practices

EHR and superbill updates

• Confirm your EHR vendor has loaded the FY 2027 code set, and ask for the date.
• Replace headers in favorites, pick lists and problem lists (the table above is a good starting point).
• Rebuild superbills and charge sheets for specialties affected: cardiology, podiatry, orthopedics, OB, ENT and bariatrics.
• Check that seventh-character fields and placeholder X’s behave correctly in your templates.

Clearinghouse and payer edits

• Ask your clearinghouse whether its scrubber edits were updated for FY 2027, and test a few claims.
• Review rejection reports daily through October and weekly after that.
• Read your top payers’ bulletins for new medical policy edits tied to the new codes.
• Log every denial that mentions an invalid or non-covered diagnosis, tagged by payer.

Provider training

• Give each specialty a one-page cheat sheet with its new codes and documentation prompts.
• Add smart phrases in the EHR that prompt for side, site, stage and cause.
• Schedule a 20-minute huddle with providers rather than another email they won’t read.

Quality control

• Spot-audit 20 to 30 October charts per provider for specificity and code validity.
• Compare your first-pass acceptance rate for October against September.
• Revisit the checklist in January, when the NCD coding update lands.

What Texas Practices Should Know About the 2027 Update

Texas is a big, payer-diverse market, and a single practice can easily bill Medicare, Texas Medicaid, several managed care plans and a handful of commercial carriers on the same day. The same code set applies to all of them. How and when each one catches up is where the differences show.

Medicare and the Texas MAC

Texas is in Medicare Jurisdiction H, which Novitas Solutions administers. Per CMS, contractors implemented the FY 2027 update on October 5, 2026, for dates of service on or after October 1. Contractor-side glitches aren’t unheard of. The Texas Medical Association has previously warned members about an October systems error in Jurisdiction H that caused claims to be rejected and required resubmission. That’s not a prediction, only a reason to watch your remittances closely in the first weeks of any fiscal year.

Texas Medicaid (TMHP) and managed care

TMHP publishes annual code-set notices, with its January HCPCS update as a familiar example, and Texas Medicaid managed care plans such as Superior HealthPlan pass those notices along to their providers. Two things to keep in mind:

• Texas Medicaid’s standard 95-day initial filing window gives you some room to correct rejected claims, but it doesn’t forgive claims nobody looks at.
• Administrative rules can differ from one managed care organization to another, so a fix that works for one plan may not for the next.

Check TMHP’s news page and each MCO’s provider alerts for FY 2027 ICD-10 guidance, rather than assuming the commercial timeline applies.

Commercial payers

UnitedHealthcare’s October 2026 medical policy update bulletins state that the annual ICD-10 update, along with quarterly CPT and HCPCS changes, is being applied across its commercial, UMR and Surest policies. For Blue Cross and Blue Shield of Texas, Aetna, Cigna and others, we’d recommend checking each payer’s provider news and policy-update pages rather than relying on a general statement of readiness. Don’t treat silence as confirmation that edits are updated.

Common ICD-10-CM Update Mistakes That Lead to Rejections

• Using the wrong code year. Applying FY 2027 codes to September visits, or FY 2026 codes to October ones.
• Billing a header. I42.0, I42.8, I49.8, M72.2, M86.8X1 to M86.8X8, D69.1, Z68.1 and Z87.890 won’t pass as billable codes.
• Truncating a code. M86.8X now needs seven characters; toxic effects and vanishing twin codes need their final characters.
• Assuming one-to-one replacements. Especially with S23.420 and T52.8X.
• Defaulting to unspecified side. If either side is documented anywhere in the record, use it.
• Forgetting the second foot. Bilateral plantar fasciitis is two codes.
• Coding “suspected” in outpatient notes. It’s not allowed, new code or not.
• Adding a BMI code without a provider diagnosis, or during pregnancy.
• Skipping the clearinghouse test. A scrubber that doesn’t know the new codes will reject accurate claims.
• Letting rejections sit. Most of these errors are cheap to fix on day three and expensive on day ninety.

How Medical Billing Services Texas(MBS Texas) Help Practices Stay Compliant with the ICD-10-CM Update

Practice managers rarely have a spare afternoon to compare an addendum file against their top 200 diagnoses. That’s where an outside team earns its keep.

At MBS Texas, our certified coders handle the annual changeover as part of ordinary work, not as a special project. For FY 2027 that means:

• Code-set mapping. We compare the CMS files against each client’s most-used codes and flag every header, deletion and new specificity option before it becomes a rejection.
• Documentation feedback. Our medical coding services team sends providers short, specialty-specific prompts rather than generic reminders.
• Payer watching. We track Texas Medicaid, Medicare and commercial payer bulletins so edits don’t catch you off guard.
• Fast denial recovery. When something does slip through, our denial management process finds the root cause, corrects it and appeals on time.
• Independent checking. Our medical audit services review a sample of post-October claims for coding accuracy and compliance.

We work with Texas practices in cardiology, orthopedics, podiatry, endocrinology, internal medicine and other specialties, and we hold ourselves to a 98 percent clean claims rate. If you’d like a second set of eyes on your own October numbers, we offer a free billing audit. No pressure, just a clear read on where claims are leaking.

Where to Find the Official 2027 ICD-10-CM Code Files and Guidelines

• CMS: the “2027 ICD-10-CM & PCS files” section at cms.gov/medicare/coding-billing/icd-10-codes has the order file, tabular list, index, addenda, conversion table and POA exempt list.
• CDC/NCHS: cdc.gov/nchs/icd/icd-10-cm/files.html hosts the code files and the official guidelines.
• Official Guidelines for Coding and Reporting, FY 2027: the document that governs sequencing and code assignment. Read the chapter-specific sections that match your specialty.
• AHA Coding Clinic for ICD-10-CM/PCS: the official source of coding advice on how to apply new codes. It’s a subscription product, and often the tie-breaker when a coding question is truly unclear.
• CMS transmittals: Change Requests 14503 and 14520 explain the Medicare contractor implementation.

Frequently Asked Questions

How many new ICD-10-CM codes are there for FY 2027?

There are 190 new billable codes. Some sources report 238 because they also count 48 non-billable headers. The update also revises four code descriptions and takes 30 codes out of billable use.

Which dates of service use the FY 2027 codes?

Any date of service or discharge from October 1, 2026 through September 30, 2027. The date you submit the claim doesn’t matter; the date of service does.

Is I42.0 (dilated cardiomyopathy) still billable?

No. I42.0 is now a header. Use I42.00 for unspecified, I42.01 for familial-genetic or I42.09 for other dilated cardiomyopathy, based on what the provider documented.

How do I code plantar fasciitis in both feet?

Use M67.A01 for the right foot and M67.A02 for the left. There’s no bilateral code, and the guidelines say to report both sides separately when no bilateral code exists.

Do the new codes have HCC values?

Not yet. CMS published its payment year 2027 initial mappings before the FY 2027 codes were final, and it assigns new codes in later mapping updates. Treat any HCC claim about the new codes as unconfirmed until CMS publishes them.

Written and reviewed by the coding and billing team at Medical Billing Services Texas (MBS Texas) | Last updated October 2026

AI tools helped with the first draft. Our team reviewed and edited it for accuracy.