ICD-10 Code M05 – Rheumatoid arthritis with rheumatoid factor (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05 – Rheumatoid arthritis with rheumatoid factor
What it is
M05 identifies rheumatoid arthritis when rheumatoid factor is present. It is used for autoimmune inflammatory arthritis documented with seropositivity, not for unspecified arthritis.
Clinical signs
Typical findings include symmetric joint pain, swelling, stiffness, and reduced range of motion. Clinical features vary; refer to documentation, especially when serology or joint involvement is described.
When to use this code
Use M05 when the provider documents rheumatoid arthritis with rheumatoid factor or seropositive RA. Apply it when the record links the arthritis diagnosis to rheumatoid factor positivity, even if the exact joint pattern is not fully detailed.
If the note only says rheumatoid arthritis without serologic status, check documentation before assigning M05. Choose the most specific subcategory available when site, organ involvement, or complications are documented.
Do not use for
Do not use M05 for rheumatoid arthritis without rheumatoid factor, which is coded elsewhere. Do not assign it when the record only mentions joint pain, osteoarthritis, or an unconfirmed inflammatory arthritis.
Coding tip
Verify that the provider explicitly documents rheumatoid factor or seropositive rheumatoid arthritis before coding M05.