Atrial Fibrillation HCC Coding Guide
Atrial Fibrillation (e.g. I48.0) maps to HCC 238 (Specified Heart Arrhythmias) under the CMS-HCC V28 risk adjustment model, with a community, non-dual, aged RAF weight of 0.299; V28 reached 100% phase-in for payment year 2026. Z79.01, long term (current) use of anticoagulants, is non-HCC under V28.
Complete HCC coding guide for Atrial Fibrillation (I48.x) including ICD-10 to HCC mapping, V28 RAF weights, type documentation, and anticoagulation coding.
Medically reviewed by Jess P., CPC · Reviewed: May 10, 2026 · Updated for CMS-HCC V28 and FY2026 ICD-10-CM
Quick Facts
HCC Categories
HCC 238, Specified Heart Arrhythmias
RAF Weight Range
0.299
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 Atrial Fibrillation map to under V28?
Atrial fibrillation (AFib) is the most common cardiac arrhythmia, affecting roughly 6 million Americans, and is a payment HCC under CMS-HCC V28. The I48 codes map to HCC 238 (Specified Heart Arrhythmias), which carries a community non-dual aged RAF of 0.299. Coding specificity still matters: document the type as paroxysmal, persistent, longstanding persistent, chronic (permanent), or unspecified, plus whether the patient is on anticoagulation and the CHA2DS2-VASc stroke risk. Atrial fibrillation and atrial flutter have separate ICD-10 codes, but both land in HCC 238, so neither outranks the other for risk capture. Make sure the arrhythmia is monitored, evaluated, assessed, or treated at the encounter so it meets MEAT and supports the diagnosis.
ICD-10 to HCC Mapping
| ICD-10 Code | Description | Billable | HCC Mapping |
|---|---|---|---|
| I48.0 | Paroxysmal atrial fibrillation | Yes | HCC 238 |
| I48.11 | Longstanding persistent atrial fibrillation | Yes | HCC 238 |
| I48.19 | Other persistent atrial fibrillation | Yes | HCC 238 |
| I48.20 | Chronic atrial fibrillation, unspecified | Yes | HCC 238 |
| I48.21 | Permanent atrial fibrillation | Yes | HCC 238 |
| I48.91 | Unspecified atrial fibrillation | Yes | HCC 238 |
| I48.3 | Typical atrial flutter | Yes | HCC 238 |
| I48.4 | Atypical atrial flutter | Yes | HCC 238 |
| I48.92 | Unspecified atrial flutter | Yes | HCC 238 |
| Z79.01 | Long term (current) use of anticoagulants | Yes | No HCC (not risk-adjusting under V28) |
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 Atrial Fibrillation from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Documentation Tips
Document the specific type of atrial fibrillation: paroxysmal, persistent, longstanding persistent, or permanent.
Record current anticoagulation therapy and specify the agent (warfarin, apixaban, rivaroxaban, etc.) for MEAT treatment criteria.
Include the CHA2DS2-VASc score to support medical decision-making and treatment rationale.
Document rate vs. rhythm control strategy and current heart rate during the encounter.
Note any prior cardioversion attempts, ablation procedures, or device implantation (pacemaker/ICD) history.
If the patient has both atrial fibrillation and atrial flutter, code both separately (I48.0-I48.21 and I48.3-I48.4).
Common Coding Mistakes
Coding I48.91 (unspecified atrial fibrillation) when the provider has documented the specific type (paroxysmal, persistent, permanent).
Confusing 'chronic' atrial fibrillation with 'permanent', chronic AFib (I48.20) is a less specific code than permanent AFib (I48.21).
Not capturing atrial fibrillation when it appears in the problem list but is not addressed at the encounter, AFib must be monitored, evaluated, assessed, or treated.
Missing the long-term anticoagulation code (Z79.01) as a supporting code, though it is not an HCC itself.
V24 to V28 Changes
Under CMS-HCC V28, the I48 atrial fibrillation and flutter codes map to HCC 238 (Specified Heart Arrhythmias), with a community non-dual aged RAF of 0.299. The transition from the prior V24 model renumbered and recalibrated the arrhythmia category rather than expanding what AFib captures, so the dollar value attached to a documented, actively managed AFib shifted with the new coefficients. AFib remains a payment HCC in V28. Keep in mind that many conditions split across several HCCs, where a base code and its manifestation codes land in different categories. AFib is simpler: every I48 code in this family rolls up to the single HCC 238, so your focus stays on type specificity, MEAT support, and clean documentation rather than chasing multiple categories.
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 10, 2026.
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