By Dave Klein, CPC, CPMA, CHC, ANJC Coding & Compliance Consultant

The official ICD-10 updates for Fiscal Year 2026 go into effect October 1st, 2025.

There were 553 code changes (487 new, 28 deleted, and 38 revised) and there were updates and clarifications to some guidelines. There are very few changes that will affect Chiropractic offices—and after the 2026 updates, we have approximately 78,785 codes!

To see the complete list of changes, go to:
https://www.cms.gov/medicare/coding-billing/icd-10-codes

Even though the 2026 updated diagnosis codes have little effect on Chiropractors, payer denials based on diagnosis coding are still a significant challenge. Every rejected claim leads to revenue loss, additional administrative work, and overall practice frustration.

However, understanding denial and claim rejection reasons can help prevent rejections and improve claim approval rates.

As stated in previous publications, payers use policies and automated code edit software to prevent payment for services when codes are reported improperly.

Many denials are based directly on the instructions and guidelines in ICD-10-CM. Coding and billing staff should be familiar with and reference these policies to avoid denials, identify the reason for a denial, and/or appeal an inappropriately denied service.

The reasons for these denials are in many cases easily avoided by Providers and typically are due to simple coding errors.

The most common errors are:

1. Using Truncating codes – A truncated code is an invalid code that is missing 1 or more additional digits. ICD-10-CM codes often require specific details in the fourth and fifth digits. Using truncated codes (missing these details) is a common error that guarantees claim denial.
2. Using Unspecified codes – Unspecified codes should only be used when the documentation does not provide enough information for a more specific code. Unspecified codes are easy to identify as the word “unspecified” is included in the description.
3. Code Missing Laterality – Using a code without proper identification of laterality will often result in automatic denial. Not all codes require that laterality is specified, however when they do (in its description, each code will identify left or right), it is critical to choose wisely.
4. Excludes 1 – This identifies when 2 diagnosis codes are mutually exclusive, e.g. two conditions that cannot be reported together. The code combination should never be used at the same time.
5. Using Deleted codes – Using a code that is no longer valid and has been either replaced with a new code or entirely deleted.
6. Improper Primary Diagnosis Code – This type of denial can be for multiple reasons. Sometimes it’s due to one of the above reasons and other times it is due to payer policy. For example, some payers will follow Medicare diagnosis hierarchy rules e.g. requiring a subluxation code as primary.

Almost all the above denials can be easily avoided by performing a quick review of claims, prior to submission.

However, many Providers and billers don’t take the time to keep on top of changes to coding rules that occur every year. Some denials are destined to occur no matter how diligently the claims are reviewed before submission.

The goal is to stay on top of all denials to ensure they are corrected and appealed (if necessary) as they occur.

Providers must be proactive and identify trends, quantify and categorize denials by tracking, evaluating, and recording them to help identify and rectify the issues causing denials in the first place.

Selecting the correct diagnosis code based on the documentation requires an excellent understanding of the coding guidelines by the physician and their staff to provide a detailed description of why they provided certain services and obtain proper reimbursement.

Getting ahead and being aware of these rules is key to not being caught with denials.

My suggestion is to perform an analysis and prepare for the 2026 ICD-10-CM changes, as follows:

1. Download the Tabular 2026 Addenda: https:// www.cms.gov/medicare/coding-billing/icd-10codes. This website will open a page direct from Medicare that will allow a user to download the changes. Providers can select the zip file named “2026 Addendum ZIP”. After opening the zip file, select the PDF document labeled “icd10cm_tabular_ addenda_2026”. This file contains all the changes for every chapter.
2. Re-familiarize yourself with the rules and determine which new codes and rules affect your practice and review the clinical concepts behind any new codes.
3. Update your software/EHR and make sure that any new codes will be available by the deadline. Some vendors will add them automatically while others may require providers to enter the codes into the system manually.
4. Remember, on and after October 1, providers should select the codes/rules based on the date of service, not based on the date the claim is sent. Claims for dates of service prior to October 1, 2025 will use the 2025 version regardless of when the claim is sent.

ABOUT THE AUTHOR:

David Klein, CPC, CPMA, CHC, is co-founder of PayDC, a web-based fully certified EHR system that focuses on compliance and reimbursement.

He is a certified professional coder and certified professional medical auditor through the American Academy of Professional Coders (AAPC) and is certified in healthcare compliance through the Health Care Compliance Board (HCCB). He is the Founder and President of DK Coding & Compliance, Inc. a health care consulting firm that focuses on audit defense, education, compliance and reimbursement issues. He can be reached at dave@paydc.com.