Rheumatoid Arthritis HCC Coding Guide
Rheumatoid Arthritis (e.g. M05.9) maps to HCC 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders) under the CMS-HCC V28 risk adjustment model, with a community, non-dual, aged RAF weight of 0.617; V28 reached 100% phase-in for payment year 2026. M05.50, rheumatoid polyneuropathy with rheumatoid arthritis of unspecified site, is non-HCC under V28.
Complete HCC coding guide for Rheumatoid Arthritis (M05-M06) including ICD-10 to HCC mapping, V28 RAF weights, organ involvement coding, and documentation requirements.
Medically reviewed by Jess P., CPC · Reviewed: May 9, 2026 · Updated for CMS-HCC V28 and FY2026 ICD-10-CM
Quick Facts
HCC Categories
HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders
RAF Weight Range
0.617
Community, non-dual, aged (V28)
Model
CMS-HCC V28 (PY2026, 100% phase-in)
9 ICD-10 codes map to payment HCCs
What HCC category does Rheumatoid Arthritis map to under V28?
Rheumatoid arthritis is a chronic autoimmune inflammatory condition affecting roughly 1.5 million Americans. Under CMS-HCC V28, the rheumatoid arthritis codes in categories M05 and M06 all map to HCC 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders), which carries a community non-dual aged RAF of 0.617. RA coding requires documenting the specific type (seropositive vs. seronegative), the joints involved with laterality, and any extra-articular organ involvement. M05 covers seropositive RA, including forms with systemic involvement such as rheumatoid lung disease, vasculitis, and myopathy, while M06 covers seronegative and other specified types. Whether you code an isolated-joint form or one with organ involvement, the codes land in the same HCC 93, so capture the most specific code supported by the documentation, disease activity, and current therapy.
ICD-10 to HCC Mapping
| ICD-10 Code | Description | Billable | HCC Mapping |
|---|---|---|---|
| M05.79 | Rheumatoid arthritis with rheumatoid factor of unspecified site without organ or systems involvement | Yes | HCC 93 |
| M05.10 | Rheumatoid lung disease with rheumatoid arthritis of unspecified site | Yes | HCC 93 |
| M06.09 | Rheumatoid arthritis without rheumatoid factor, multiple sites | Yes | HCC 93 |
| M06.00 | Rheumatoid arthritis without rheumatoid factor, unspecified site | Yes | HCC 93 |
| M05.50 | Rheumatoid polyneuropathy with rheumatoid arthritis of unspecified site | Yes | No HCC (not risk-adjusting under V28) |
| M05.30 | Rheumatoid heart disease with rheumatoid arthritis of unspecified site | Yes | HCC 93 |
| M05.9 | Rheumatoid arthritis with rheumatoid factor, unspecified | Yes | HCC 93 |
| M06.9 | Rheumatoid arthritis, unspecified | Yes | HCC 93 |
| M06.811 | Other specified rheumatoid arthritis, right shoulder | Yes | HCC 93 |
| M06.812 | Other specified rheumatoid arthritis, left shoulder | Yes | HCC 93 |
RAF weights are community, non-dual, aged base coefficients from the CMS-HCC V28 model (PY2026). Verify against the latest CMS rate announcement for payment calculations.
HCC Buddy maps Rheumatoid Arthritis from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Documentation Tips
Document whether the RA is seropositive (M05) or seronegative (M06) based on rheumatoid factor and anti-CCP antibody status.
Specify the joints involved with laterality (right, left, bilateral) and site (hand, wrist, knee, etc.).
Document any extra-articular manifestations: rheumatoid lung disease, vasculitis, neuropathy, or cardiac involvement.
Record current disease activity using validated measures (DAS28, CDAI) and document flares vs. remission.
List current DMARD therapy (methotrexate, biologics, JAK inhibitors) with dosing to satisfy MEAT treatment criteria.
Document functional limitations and joint deformities when present.
Common Coding Mistakes
Using M06.9 (rheumatoid arthritis, unspecified) instead of specifying seropositive (M05) or seronegative (M06.0) when lab results are available.
Not capturing extra-articular manifestations of RA that map to additional or more specific codes.
Failing to document laterality and specific joint sites, resulting in 'unspecified site' codes.
Coding osteoarthritis (M15-M19) instead of rheumatoid arthritis when the provider documents an inflammatory autoimmune arthritis.
V24 to V28 Changes
Under CMS-HCC V28, rheumatoid arthritis maps to HCC 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders), with a community non-dual aged RAF of 0.617. In the prior V24 model these codes sat in a broadly named rheumatoid arthritis and inflammatory connective-tissue category; V28 renumbered and renamed the grouping and recalibrated the RAF, but the M05 and M06 RA codes continue to risk-adjust. The core coding discipline is unchanged: confirm an inflammatory autoimmune diagnosis (not osteoarthritis), document seropositive vs. seronegative status, joint sites with laterality, and any organ involvement, then support each captured code with MEAT-level evidence so HCC 93 is defensible on audit.
Related Conditions
Related references
Sources
RAF weights are community, non-dual, aged base coefficients from the CMS-HCC V28 model (PY2026). Verify against the latest CMS Rate Announcement for payment.
Verified current to CMS-HCC V28, payment year 2026 — last reviewed May 9, 2026.
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