OIG Audit Flags $180M Medicare Advantage Overpayments

Federal Audits Find Humana, UnitedHealthcare Medicare Advantage Plans Overpaid Nearly $180 Million

The U.S. Department of Health and Human Services Office of Inspector General (HHS OIG), the federal watchdog that audits Medicare and Medicaid spending for improper payments, released audit reports finding that a HumanaChoice Medicare Advantage plan and a UnitedHealthcare of Wisconsin Medicare Advantage plan received close to $180 million in overpayments over a two-year audit period. Healthcare Dive reported the findings on September 17, 2026, based on the newly released OIG audits. The audits center on a practice known as upcoding, in which diagnosis codes submitted for a patient make that person appear sicker than their medical records support, which raises the risk score Medicare uses to calculate monthly payments to Medicare Advantage insurers.

Medicare Advantage (MA) is the private-plan alternative to Original Medicare, in which CMS pays insurers a set monthly amount per enrollee that is adjusted up or down based on each member's documented health conditions. That process, called risk adjustment, is intended to pay plans more for covering people who are genuinely sicker and costlier to treat. According to Healthcare Dive's reporting, the OIG audits found that HumanaChoice and UnitedHealthcare of Wisconsin submitted diagnosis codes for conditions that medical record reviews could not adequately support, which the OIG says led to inflated risk scores and higher payments than the plans should have received. Read the original report from Healthcare Dive: Federal watchdog accuses Humana, UnitedHealthcare Medicare Advantage plans of upcoding.

Why Diagnosis Codes Drive Medicare Advantage Payments

Every Medicare Advantage enrollee is assigned a risk score built from diagnosis codes submitted by their plan, using a CMS model based on Hierarchical Condition Categories (HCCs). A higher risk score signals a sicker, more expensive patient and results in a larger monthly payment to the insurer. Because that formula rewards documented diagnoses, OIG has run Risk Adjustment Data Validation (RADV) audits of Medicare Advantage plans for more than a decade, repeatedly flagging insurers, including large national companies, for diagnosis codes that reviewers could not verify against medical records. The Humana and UnitedHealthcare findings reported by Healthcare Dive follow that same pattern.

The reporting reviewed for this article did not include a public response from Humana or UnitedHealthcare to these specific findings, so it is not yet clear whether either company disputes the OIG's methodology or plans to appeal. Insurers have challenged similar OIG audits in the past on the grounds that the agency's sampling and extrapolation methods can overstate the scale of overpayments; whether that pattern applies to this case has not been confirmed in the source material.

It is also worth noting what these audits do not establish. An OIG overpayment finding is a program-integrity determination about billing accuracy, not a criminal fraud charge, and the described findings do not allege that either company acted with intent to deceive. The typical outcome of a RADV audit is a repayment demand from CMS, sometimes contested through appeal, rather than an immediate change to an enrollee's coverage.

What Seniors Comparing Medicare Advantage Plans Should Watch

For current and prospective Medicare Advantage enrollees, this news is a reminder to evaluate plans on documented performance rather than name recognition alone. A few practical steps can help:

• Read your Annual Notice of Change (ANOC) each fall. Overpayment findings like these can eventually influence CMS payment policy, which can later show up as changes to premiums, copays, or supplemental benefits such as dental or vision coverage.
• Review your medical records and Explanation of Benefits periodically. Because risk-adjustment payments are tied to the diagnosis codes in your chart, it is worth confirming that the conditions listed on your records match what your doctor has actually diagnosed and discussed with you.
• Use Medicare's annual enrollment window to compare options. The Medicare Open Enrollment Period runs October 15 through December 7, 2026, and is the main window for switching Medicare Advantage plans or returning to Original Medicare for the 2027 plan year.
• Talk to a licensed insurance agent or use Medicare's Plan Finder. A licensed agent or the official Medicare.gov Plan Finder tool can help you compare star ratings, total costs, and network coverage across plans, independent of any single audit finding.

Readers can review the full details in Healthcare Dive's original report, published September 17, 2026, on the HHS OIG audits of HumanaChoice and UnitedHealthcare of Wisconsin.