# ICDcodes.org — Full Reference ## 1. About ICDcodes.org ICDcodes.org is an independent reference website for ICD-10-CM diagnosis codes. It is not affiliated with, endorsed by, or operated by the CDC, NCHS, CMS, or any other government agency. It is built and maintained by a software developer, not by a certified medical coder — the site's approach to trust is provenance (every fact traces back to an official source file or a documented, deterministic rule) rather than a claimed medical credential. ## 2. What ICD-10-CM is ICD-10-CM (International Classification of Diseases, 10th Revision, Clinical Modification) is the code set the United States uses to record diagnoses on medical records and insurance claims. It is the U.S. clinical modification of the World Health Organization's ICD-10, maintained specifically for U.S. use by the CDC's National Center for Health Statistics (NCHS) and the Centers for Medicare & Medicaid Services (CMS). It is distinct from ICD-10 itself, which is the WHO's international classification used for disease statistics rather than U.S. billing. ## 3. How the site's database works Every code, description, and instructional note (Excludes1, Excludes2, Code First, Use Additional Code, Includes, inclusion terms, 7th-character definitions) is generated directly from the official ICD-10-CM release files — nothing is copied or paraphrased from another reference site. Billable status comes from the flag in the official order file rather than being inferred. Change classifications (added / revised / expanded / removed) are derived from the official year-over-year addenda file and reconciled against the totals CMS publishes in that same file. ## 4. Data sources - ICD-10-CM order file (codes, descriptions, billable flag) - ICD-10-CM addenda file (year-over-year changes) - ICD-10-CM Tabular List XML (chapters, sections, instructional notes) - ICD-10-CM Official Guidelines for Coding and Reporting: https://ftp.cdc.gov/pub/health_statistics/nchs/publications/ICD10CM/2027/ICD-10-CM-October-1-2026-FY27-Guidelines.pdf - Published by: CDC / National Center for Health Statistics, at https://ftp.cdc.gov/pub/health_statistics/nchs/publications/ICD10CM/, and CMS at https://www.cms.gov/ Full detail: https://icdcodes.org/data-sources ## 5. Editorial methodology Official source data is downloaded, parsed and structured at build time. Content is not manually rewritten from the source files. Every code page's instructional notes are printed exactly as CMS/CDC publish them. Where the site makes an inference rather than reporting a fact directly from the source (for example, flagging a code as "unspecified"), the rule behind that inference is stated on the page rather than presented as an unexplained judgment. The site is rebuilt when a new fiscal-year release is published. Full detail: https://icdcodes.org/editorial-policy ## 6. Current ICD-10-CM year Fiscal year 2027, effective 2026-10-01 through 2027-09-30. The FY2027 update: 190 new codes, 15 existing codes subdivided into more specific codes (the subdivided codes can no longer be submitted after the effective date), 15 codes removed, 4 descriptions revised. Full detail: https://icdcodes.org/fy2027-changes ## 7. Site sections - Code search: https://icdcodes.org/search - Browse by chapter/section/category: https://icdcodes.org/icd-10-cm - Conditions A-Z (condition-to-code lookup): https://icdcodes.org/icd-10-code-for - Coding guides: https://icdcodes.org/guides - Current-year updates: https://icdcodes.org/fy2027-changes - Neoplasm table: https://icdcodes.org/neoplasm - Table of Drugs and Chemicals: https://icdcodes.org/drug - Batch code checker: https://icdcodes.org/check - Code comparison (Excludes1 pairs): https://icdcodes.org/compare ## 8. Coding guides ### Billable vs Non-Billable ICD-10 Codes Explained Why can't I submit every ICD-10-CM code on a claim? Roughly a quarter of ICD-10-CM codes cannot be submitted at all. The rule that decides it, and why a valid code is not the same as a covered one. https://icdcodes.org/guides/what-billable-means ### Excludes1 vs Excludes2 in ICD-10-CM: The Difference What is the difference between an Excludes1 and an Excludes2 note? The most misread convention in ICD-10-CM. One forbids reporting two codes together; the other explicitly permits it. https://icdcodes.org/guides/excludes1-vs-excludes2 ### Unspecified codes and denial risk When is it acceptable to report an unspecified ICD-10-CM code? Unspecified codes are valid and sometimes the only correct choice — but they are also the most common cause of a specificity denial. https://icdcodes.org/guides/unspecified-codes ### ICD-10-CM 7th Characters (A, D, S) and Placeholder X How do 7th characters work in ICD-10-CM, and when do I need a placeholder X? Over half of all ICD-10-CM codes carry a 7th character. What each one means, why a code can be invalid without it, and when the placeholder X fills the gap. https://icdcodes.org/guides/seventh-characters ### Code first, use additional code, and code also Which ICD-10-CM code should be sequenced first? The etiology/manifestation convention decides sequencing for you. How to recognise a manifestation code and why it can never be listed first. https://icdcodes.org/guides/code-first-use-additional ### The ICD-10-CM update cycle When do ICD-10-CM codes change, and which code set applies to my claim? Codes change on October 1 and sometimes April 1, with no grace period. Why date of service — not date of billing — decides which set applies. https://icdcodes.org/guides/update-cycle ## 9. Tools - Batch code checker (https://icdcodes.org/check): paste a list of codes, see which are no longer billable this fiscal year. - Compare codes (https://icdcodes.org/compare): Excludes1 code pairs shown side by side, with the rule that separates them. - Neoplasm table (https://icdcodes.org/neoplasm): code a tumor by site and behavior. - Table of Drugs and Chemicals (https://icdcodes.org/drug): poisoning, adverse effect and underdosing codes by substance. ## 10. Key terminology - **Billable code**: a code that is complete — no further subdivision exists beneath it. A code with children is a header code: it organizes the classification but cannot be submitted on a claim. - **Header code**: a code that has one or more more-specific codes beneath it; not billable on its own. - **Excludes1**: the excluded code can never be reported together with the code it appears under, except when the two conditions are genuinely unrelated to each other. - **Excludes2**: the excluded condition is not part of the condition it appears under; both may be reported together when documentation supports it. - **Unspecified code**: valid, and sometimes the only correct choice, but the most common cause of a specificity denial when a more specific code was available. - **7th character**: an extension (commonly A/D/S for initial encounter / subsequent encounter / sequela) required by certain categories, using placeholder X when the code is shorter than 7 characters without it. - **Code First / Use Additional Code**: sequencing conventions for the etiology/manifestation pattern — a manifestation code can never be sequenced first. ## 11. Important internal resources - Home: https://icdcodes.org/ - HTML sitemap: https://icdcodes.org/site-map - XML sitemap index: https://icdcodes.org/sitemap-index.xml - About: https://icdcodes.org/about - Contact: https://icdcodes.org/contact - Data sources: https://icdcodes.org/data-sources - Editorial policy: https://icdcodes.org/editorial-policy - Disclaimer: https://icdcodes.org/disclaimer - Privacy: https://icdcodes.org/privacy - Terms: https://icdcodes.org/terms ## 12. Disclaimer ICDcodes.org is provided for reference and educational purposes. It does not provide medical advice, medical diagnosis, or professional coding services. Code selection must be based on the patient's documentation and the ICD-10-CM Official Guidelines for Coding and Reporting; coverage and reimbursement decisions are governed by the relevant payer's own policy, not by this site. Full disclaimer: https://icdcodes.org/disclaimer ## 13. Authoritative external sources - CDC / National Center for Health Statistics — ICD-10-CM publications: https://ftp.cdc.gov/pub/health_statistics/nchs/publications/ICD10CM/ - ICD-10-CM Official Guidelines for Coding and Reporting (FY2027): https://ftp.cdc.gov/pub/health_statistics/nchs/publications/ICD10CM/2027/ICD-10-CM-October-1-2026-FY27-Guidelines.pdf - CMS (Centers for Medicare & Medicaid Services): https://www.cms.gov/