HCC Coding Accuracy and Risk Adjustment Enforcement

Medicare Advantage capitation payments are calculated under the CMS-HCC (Hierarchical Condition Category) risk adjustment model, which converts the diagnosis codes submitted for each enrollee into a risk score that drives the plan's monthly payment from CMS. When a diagnosis code is not supported by the medical record, or is added to a chart after the fact to raise that score, the payment it generates is an overpayment. The exposure runs beyond the Medicare Advantage plan. Physicians and physician groups whose coding and documentation produced the unsupported diagnosis face chart review requests, extrapolated repayment demands, and False Claims Act liability of their own.

How the CMS-HCC Model Converts Diagnoses Into Payment

CMS assigns each Medicare Advantage enrollee a risk score built from demographic factors and the Hierarchical Condition Categories (HCCs) mapped to the diagnosis codes submitted during the payment year. Each HCC carries its own payment weight, and more, or more severe, HCCs raise both the score and the capitation payment CMS pays the plan. The model depends on physicians documenting a diagnosis that was actually monitored, evaluated, assessed, or treated during the encounter. A diagnosis copied forward from a problem list or an old note, without contemporaneous support, does not meet that standard, even though it still generates payment.

CMS's RADV Audit Program and the Extrapolation Fight

CMS validates HCC-supported payments through Risk Adjustment Data Validation (RADV) audits under 42 CFR 422.310, which require Medicare Advantage organizations to submit the underlying medical records for a sample of enrollees and remit any resulting overpayment. The February 1, 2023 RADV final rule (88 FR 6665) authorized CMS to extrapolate a sample's error rate across a plan's entire contract for payment year 2018 forward, a change CMS estimated would recover approximately $4.7 billion over ten years. A federal court vacated that extrapolation authority in September 2025 on procedural grounds. CMS has appealed and recovers only on the enrollees actually sampled. The underlying obligation, that every submitted diagnosis be supported by the medical record, has not changed. RADV sits alongside the broader Medicare contractor audit process.

False Claims Act Exposure for Physician Groups

DOJ has built a growing line of False Claims Act cases on unsupported HCC coding, and increasingly reaches past the Medicare Advantage plan to the physician groups and management companies that produced the diagnosis codes. In August 2026, a Jacksonville, Florida management services organization, Complete Health Partners Holdings, agreed to pay $14.1 million to resolve allegations that it pushed physicians and coders to add diagnosis codes under HCC 55 (drug and alcohol dependence) and HCC 59 (major depressive, bipolar, and paranoid disorders) that were not clinically valid or supported by the medical record, conduct DOJ tied to a risk-sharing compensation arrangement that rewarded higher risk scores. The physicians who signed those charts, not only the plan that submitted them, sit inside that exposure.

A risk-sharing arrangement that pays a physician group more for a higher risk score is the same arrangement DOJ points to as motive in a False Claims Act case.

Chart Review Requests and Retrospective Diagnosis Additions

Physicians in Medicare Advantage networks routinely receive chart review requests, often from a vendor retained by the plan, asking them to confirm a diagnosis found on retrospective record review or to complete an addendum for a condition allegedly treated but not coded. Every addendum becomes part of the record CMS or DOJ will examine if the plan's coding practices are later questioned, and an extrapolated recoupment demand can follow a RADV finding. A physician who signs off on a diagnosis the encounter note does not support is creating the same documentation gap that turns an audit into a False Claims Act referral. Practices facing an extrapolated demand should review our companion piece on challenging extrapolation in Medicare overpayment demands.

Why Early Legal Counsel Is Critical

It is critical that physicians and physician groups promptly retain experienced healthcare defense counsel upon receiving a RADV audit notice, a chart review request tied to risk adjustment, a subpoena, or any other government inquiry into HCC coding. Early legal intervention can protect the practice's rights, ensure documentation requests are answered without creating new exposure, avoid inadvertent admissions, and preserve defenses that may otherwise be lost. Delaying representation can significantly affect the outcome of the matter.

How Health Law Alliance Can Help

Health Law Alliance defends physicians and physician groups against Medicare audits, including the RADV and HCC coding disputes that can escalate into False Claims Act exposure. Our bench includes a former federal prosecutor and a former senior healthcare compliance executive, background that shapes how we evaluate which diagnosis codes actually put a practice at risk. If your practice has received a RADV audit notice, a chart review request, or a government inquiry involving HCC coding, contact us for a free, confidential consultation.