ICD-11 for US Health Organizations: What Changes, Where the US Stands, and What to Do Now

Most US coders will not assign an ICD-11 code for years. But the rest of the world has already started, the choices made now will shape what a US move looks like, and the last time the US waited, it paid for it. Here is the plain-English version.

What ICD-11 is

ICD-11 is the World Health Organization’s eleventh revision of the International Classification of Diseases. The World Health Assembly adopted it on May 25, 2019, and it came into effect on January 1, 2022. It is free to use, and WHO describes it as built for electronic health records, with the classification, coding tool and translation tools all delivered through APIs.

It is not just a longer list. WHO describes it as a statistical classification with an embedded clinical terminology in one system, so the same content can serve a cause-of-death record, a clinical note and a claim.

What actually changes

The biggest change is how detail is added. ICD-10-CM mostly builds detail into the code, so a new combination needs a new code. ICD-11 keeps the number of core categories smaller and lets you add detail with extension codes, clustered with the stem code. This is called post-coordination.

The content has changed too. According to WHO, ICD-11 adds new chapters on diseases of the immune system, sleep-wake disorders and conditions related to sexual health, plus an optional chapter on traditional medicine conditions. Mental health diagnoses were reorganized, and new ones were added, such as complex post-traumatic stress disorder, prolonged grief disorder and gaming disorder.

One change matters for documentation: ICD-11 carries qualifiers for the diagnostic process itself: suspected, probable, confirmed, ruled out, personal history and family history. That makes the classification closer to how clinicians actually describe uncertainty.

Where the United States stands

The National Committee on Vital and Health Statistics (NCVHS), HHS’s advisory body on health data, describes three separate US decisions. One is cause-of-death reporting, which is tied to US membership in WHO and led by the National Center for Health Statistics. Another is morbidity reporting for health care and public health. The third is payment: ICD is a HIPAA-designated code set, so moving diagnosis coding on claims is a federal mandate that needs HHS rulemaking.

The US took about 25 years after WHO endorsed ICD-10 to use it for claims, which NCVHS says made it the last industrialized country to do so, with “on-again, off-again” deadlines that caused rework and cost. NCVHS recommended a research agenda in 2019 and again in 2021, and in April 2024 asked HHS to name one office responsible for coordinating ICD-11 morbidity coding. As of October 13, 2026, we could not find a published US implementation date or a proposed rule.

The question that shapes everything: does the US need its own version?

The US uses a clinical modification of ICD-10 (ICD-10-CM) because the WHO version was not detailed enough for US payment and clinical needs. WHO expects that ICD-11’s structure removes the need for country modifications. NCVHS made the first item on its research list the question, “is a CM needed or not?”, and warned that building a US clinical modification would extend the timeline, add cost and require ongoing curation.

There is little evidence yet. A 2020 study in the Journal of the American Medical Informatics Association recoded 388 ICD-10-CM codes from six disease areas into ICD-11 by hand. Only 9% had an exact match without post-coordination. Another 49% could be fully represented with post-coordination, and 43% were only partly representable.

You may see a one-to-one match percentage quoted in vendor articles. We could not trace those figures to a primary source, so we rely on the peer-reviewed study above, with its limits stated.

What it would touch in a revenue cycle

This is our analysis, not a federal statement, because no US rule exists to describe. If diagnosis coding on claims moved to a new code set, these are the places that would need work:

• Grouper and DRG logic, which is built on diagnosis and procedure codes and would need to be rebuilt, not just mapped.
• Payer edits and policy lists: coverage determinations, prior authorization lists and medical-necessity rules that name diagnosis codes.
• Risk adjustment, where models map diagnosis codes to condition categories.
• Quality measures and reporting value sets that list diagnosis codes.
• Historical comparability: trend reports that span two code sets.
• Documentation templates, CDI queries and coder training.
• Vendor and payer contracts, interfaces and data models that assume a single diagnosis code system.

If your organization uses AI-assisted coding, add one more: how the vendor’s model and validation would handle a second code system. See our governance checklist and our analysis of AI coding tools for the controls that apply either way.

What to do now

None of these depends on a date. Each one makes you better at ICD-10-CM today and cheaper to move when a date arrives.

1. Raise documentation specificity now. Clinical detail is the raw material for any classification, and ICD-11 rewards it more than ICD-10-CM does.
2. Inventory where diagnosis codes live: systems, interfaces, edits, groupers, contracts, models and reports. You cannot plan a change you cannot see.
3. Ask vendors in writing: what is your ICD-11 plan, can the system hold more than one code set with effective dates, what will it cost, and who pays?
4. Keep the source documentation with each code, and make sure your data models carry the code system and version. That is what makes recoding possible later.
5. Build literacy cheaply. WHO’s browser and coding tool are free. Code a small sample of your most common conditions to see how clusters read, and train a few champions.
6. Watch the right places: NCVHS meetings, the NCHS ICD pages, CMS rulemaking and the Federal Register. A proposed rule would start the planning clock.
7. Avoid the two common mistakes: buying “ICD-11 ready” tools without specifics, and spending on mass training before a date exists.

Frequently asked questions