The FY 2027 ICD-10-CM codes take effect today, October 1. If your practice isn’t completely ready, don’t panic—but don’t wait, either. Starting with today’s dates of service, you need to use the FY 2027 ICD-10-CM code set. That includes 190 new codes, 30 deleted codes and four revised code descriptions.

And this isn’t simply a coding-book change. An outdated diagnosis code hiding in your EHR, superbill, provider favorites or template can now result in a rejected claim, additional staff work and delayed payment.

Here’s what you should check today—and what you should monitor over the next 30 days.

1. Make Sure Your EHR Is Actually Ready

Don’t assume that because your vendor updated the ICD-10-CM code set, everything inside your system is current. Your practice may have customized:

• Diagnosis pick lists
• Provider favorites
• Problem lists
• Templates
• Superbills
• Claim edits
• Coding shortcuts
• Internal cheat sheets

Any of these could still contain outdated codes. Coding and compliance expert Keisha Wilson warns against assuming, “Our EHR vendor will handle it.” Vendors may update the underlying code set, but they don’t necessarily update every customized workflow your practice has built around it.

What to do today: Have someone test several of your practice’s most commonly used diagnosis-code workflows. Make sure applicable new codes are available, deleted codes aren’t being selected for October 1 dates of service, and revised descriptions appear correctly.

2. Pay Close Attention to the Date of Service

This is particularly important during the next several weeks. For outpatient services, the applicable ICD-10-CM code set is based on the date of service, not the date you submit the claim.

So, if you’re billing a patient encounter from September 30 today, you don’t automatically use a FY 2027 code simply because you’re submitting the claim in October. For encounters beginning today, October 1, 2026, the FY 2027 code set applies.

That distinction can become especially important if providers have unfinished September charts or your billing department is working through older claims.

What to do today: Make sure your billing and coding teams understand that the transition is driven by the encounter date—not the claim-submission date.

3. Don’t Focus Only on the 190 New Codes

New codes tend to get most of the attention. But your biggest immediate denial risk may come from the 30 deleted codes. If one of those codes is still sitting in a provider’s favorites, superbill or template and gets used for an October 1 date of service, you may have a problem.

Also pay attention to the four revised code descriptions. A code number may look familiar even though its description or associated coding instructions have changed. A familiar-looking code shouldn’t automatically be treated exactly as it was last year.

What to do today: Search your EHR, superbills and internal coding tools for the deleted and revised codes affecting your specialties.

4. Check More Than the Code Number

Don’t stop once you’ve confirmed that a diagnosis code still exists. Review the surrounding instructions in the Tabular List. Changes may involve:

• Excludes1 and Excludes2 notes
• Code first instructions
• Use additional code instructions
• Laterality
• Required additional characters
• Seventh characters
• Sequencing requirements

Instructional notes can change even when a code number doesn’t. That’s why you need to look at what changed around the code, not simply the code itself. And don’t code directly from the Alphabetic Index. Use it to locate the diagnosis, then verify your final selection in the Tabular List and review the applicable instructions.

5. Make Sure Your Providers Document the New Specificity

A new, more specific diagnosis code doesn’t give you permission to assume details that aren’t documented.

If the new code requires laterality, the medical record needs to identify the appropriate side. If a pregnancy code requires trimester specificity, the documentation must support the trimester. If an oncology code distinguishes primary from secondary malignancy, the record must support that distinction.

The same rule applies throughout the new code set.

More specificity in ICD-10-CM means your documentation may need more specificity, too.

The existence of a more specific code doesn’t give your coder permission to manufacture specificity.

What to do today: Identify the new codes most likely to be used in your practice and determine what information your providers must document to support them.

6. Watch Your Use of Unspecified Codes

This is also a good time to examine how often your practice relies on unspecified diagnosis codes. An unspecified code isn’t automatically incorrect. Sometimes the documentation legitimately doesn’t support greater specificity, or an unspecified code is the appropriate available choice.

The problem occurs when the record does contain more detail, but your provider or coder selects an unspecified option because it’s familiar, faster or easier to find.

What to do now: Begin tracking frequently used unspecified diagnoses. If your documentation routinely supports something more specific, determine whether you have an education, workflow or EHR-selection problem.

7. Start Watching Rejections and Denials Today

Your first indication that something was missed may come from your clearinghouse or payer. Pay particular attention to:

• Invalid diagnosis codes
• Deleted codes
• Unexpected unspecified-code usage
• Medical-necessity denials
• Diagnosis-pointer problems
• New-code rejections
• Provider-specific patterns
• Specialty-specific denial trends

If a diagnosis you’ve used successfully for years suddenly rejects for an October date of service, don’t simply resubmit the claim.

Check the FY 2027 code set. Was the code deleted? Expanded? Revised? Does a more specific code now apply? This troubleshooting approach when a familiar diagnosis suddenly starts rejecting after an annual update.

8. Don’t Assume a Valid Code Guarantees Payment

Even if a code is valid for FY 2027, that doesn’t mean every payer will cover the service when you report it. Check applicable payer policies when necessary, including Medicare National Coverage Determinations (NCDs) and Local Coverage Determinations (LCDs).

But don’t work backward from the payer policy. In other words, don’t find a diagnosis on an LCD that will get the procedure paid and then choose that diagnosis unless the patient’s medical record actually supports it.

Your documentation drives your code selection—not the reimbursement result you want.

9. Schedule Your First Post-Implementation Audit Now

Don’t consider your ICD-10 implementation finished simply because the new codes went live today. The next 30 days are when you’ll find out whether your process actually works.

Put that first audit on your calendar now. Look at actual claims and ask:

• Are providers selecting the correct new codes?
• Are deleted codes still slipping through?
• Does the documentation support the reported specificity?
• Are you seeing more unspecified coding than expected?
• Are particular providers or specialties generating more errors?
• Are new denials beginning to appear?

Finding a problem after 30 days gives you an opportunity to correct it. Finding the same problem six months from now could mean hundreds or thousands of affected claims.

Your October 1 ICD-10 Action List

If your practice is still working through the transition today, prioritize these steps:

1. Confirm the FY 2027 codes are live in your system.
2. Remove applicable deleted codes from October 1 workflows.
3. Review revised codes and instructional notes.
4. Check provider favorites, templates and superbills.
5. Confirm your claim edits and scrubbers recognize FY 2027 codes.
6. Educate providers on specialty-specific changes.
7. Identify documentation changes needed to support new specificity.
8. Monitor rejected claims and denials immediately.
9. Track unspecified-code usage.
10. Schedule a post-implementation audit within 30 days.

Most importantly, don’t treat October 1 as the finish line.

Implementation isn’t complete when the new code set is loaded. It’s complete when your practice can demonstrate that the codes are being used accurately and appropriately.

Keep Your Team Ahead of the Next Change

ICD-10-CM isn’t the only rule your practice has to keep up with. Coding, billing, reimbursement and compliance requirements continue to change throughout the year.

With Healthcare Training Leader’s Annual All-Access Pass, your entire team gets ongoing access to expert-led training designed specifically for medical practices. Instead of scrambling after a change takes effect, your billers, coders, managers, providers and other staff can get practical guidance to help prevent denials, strengthen compliance and protect your practice’s revenue.

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