How to look up an ICD-10-CM code

A diagnosis code found by guessing is a denial waiting to happen. Professional coders follow a fixed workflow, and it takes under a minute once it is habit:

1. Start with the diagnosis, not the code

Work from the provider's documented diagnosis in the chart, never from a previous claim, a superbill habit, or what was coded last visit. Copying forward is how deleted and non-specific codes survive for years.

2. Find the main term in the alphabetic index

Look up the condition itself (Diabetes, Fracture, Hypertension), not the body part or the symptom when a confirmed diagnosis exists. Follow the subterms for site, type, and cause. The index gives a candidate code, often with a dash showing more characters are required.

3. Verify in the tabular list - always

The index alone is never enough. In the tabular list, read the notes at the section, category and subcategory level: Includes, Excludes1 and Excludes2 notes, "code first", "use additional code", and 7th-character instructions all change what may be billed. Our chapter and category pages show every billable code under a category, which makes this step fast.

4. Code to the highest specificity

If the category offers a more specific code that matches the documentation, the shorter code is wrong even though it looks close. Laterality, episode of care, trimester, and type (such as Type 1 vs Type 2 diabetes) are the usual missing pieces - if the chart does not say, query the provider.

5. Check the date of service against the code year

ICD-10-CM changes every October 1. A code valid last September may be deleted or split this year. FY2027 runs October 1, 2026 to September 30, 2027; see the FY2027 update guide for what changed.

Try it: search ICD-10-CM by code or keywords, then open the category page to verify the full family of codes before you bill.