Condition guide
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.
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)
10 ICD-10 codes map to payment HCCs
How coders write it
Chart notes, problem lists, and queries rarely spell out Rheumatoid Arthritis. The shorthand you will actually see:
Whatever the note calls it, the payment question is the same: how the ICD-10-CM code resolves to a payment HCC.
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 multiple sites 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 | HCC 93 |
| 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.
Coder workflow notes
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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.
MEAT documentation examples for Rheumatoid Arthritis
A diagnosis only counts toward risk adjustment when the encounter note shows the provider engaged with it. These are the kinds of entries that satisfy the MEAT documentation standard for Rheumatoid Arthritis:
MMonitor
“DAS28 today 3.8, improved from 4.6 three months ago.”
“CRP 12 and ESR 28, both trending down on methotrexate.”
“Annual hand films: stable erosions, no new joint space loss.”
EEvaluate
“Joint exam: four tender and two swollen joints, MCPs and wrists.”
“Hepatic panel reviewed for methotrexate toxicity: within normal limits.”
“Morning stiffness now 30 minutes, down from two hours.”
AAssess
“Seropositive rheumatoid arthritis, moderate activity despite methotrexate.”
“RA in low disease activity on adalimumab.”
“Seronegative RA of hands and wrists, stable.”
TTreat
“Methotrexate increased to 20 mg weekly with folic acid.”
“Started adalimumab 40 mg every other week.”
“Prednisone bridge 10 mg daily while the biologic takes effect.”
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. That is a raise: the V24 predecessor, HCC 40 (Rheumatoid Arthritis and Inflammatory Connective Tissue Disease), paid 0.421, making RA one of the categories V28 values more, not less. One V24 habit to retire: M05.50 (rheumatoid polyneuropathy) used to earn dual credit, HCC 40 plus the V24 neuropathy category HCC 75, while V28 resolves it to HCC 93 alone. 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.
| Aspect | V24 (through PY2025) | V28 (PY2026) |
|---|---|---|
| RA codes (M05.x, M06.x) | HCC 40, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease, RAF 0.421 | HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders, RAF 0.617 |
| RA with polyneuropathy (M05.50) | Dual credit: HCC 40 plus neuropathy category HCC 75 | HCC 93 only |
| Direction of change | HCC 40 paid RAF 0.421 | HCC 93 pays RAF 0.617, one of the categories V28 values more |
RAF values are community, non-dual, aged base coefficients for each model's payment year. To see what these weights do to a real patient total, run the codes through the RAF score calculator.
Rheumatoid Arthritis coding FAQs
What HCC is rheumatoid arthritis in V28?
HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders, with a community, non-dual, aged RAF weight of 0.617 for payment year 2026. Every M05 and M06 rheumatoid arthritis code in this guide resolves to that single category, up from 0.421 under the V24 predecessor HCC 40.
Does M06.9 (RA, unspecified) risk-adjust?
Yes. M06.9 maps to HCC 93 at the same 0.617 weight as the specific codes. Specificity still matters for audit defense: when rheumatoid factor and anti-CCP results are in the chart, an unspecified code invites the question of whether the diagnosis was fully reviewed, so code M05 or M06.0x when the labs support it.
Is osteoarthritis an HCC?
No. The osteoarthritis codes (M15 through M19) carry no payment HCC under V28, which is why distinguishing inflammatory autoimmune arthritis from degenerative joint disease matters so much in risk adjustment. Only a documented inflammatory diagnosis like rheumatoid arthritis supports HCC 93.
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 July 16, 2026.
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