Humana has rejected all four recommendations in a new federal audit of its HumanaChoice Medicare Advantage contract, including a call to review 212 additional enrollee-years of diagnosis codes that auditors flagged as possible data-entry errors. The HHS Office of Inspector General, which issued the audit of contract H5216 on September 10, 2026, found that medical records did not support the codes in 178 of 220 sampled enrollee-years. It estimated HumanaChoice was overpaid at least $130.9 million for 2020 and 2021 and recommended that Humana refund that amount.
How the HumanaChoice audit worked
Medicare pays private Medicare Advantage plans a monthly amount per member that rises with the member’s recorded health conditions. Plans gather diagnosis codes from doctors and hospitals and send them to CMS, which converts them into risk scores for the following year. A code that is not supported by the patient’s chart inflates that score and the payment.
According to the OIG audit, HumanaChoice is a preferred provider organization administered by Louisville, Kentucky-based Humana, Inc., with members in multiple states. It covered 1,730,650 enrollees under contract H5216 as of December 2021, and CMS paid it approximately $37.8 billion for the 2020 and 2021 payment years.
Auditors sampled 20 enrollee-years in each of 11 diagnosis groups that OIG considers at high risk of miscoding. The error rates were steep. Unsupported codes turned up in all 20 sampled acute stroke cases, 19 of 20 for heart attack, breast cancer, colon cancer and ovarian cancer, 18 of 20 for lung cancer, 16 of 20 for embolism and prostate cancer, 13 of 20 for sepsis and 9 of 20 for severe pressure ulcers. Together, the unsupported codes produced $669,237 in overpayments in the sample, which OIG projected across the contract.
An independent medical review contractor checked each sampled chart. A common problem was a past illness billed as a current one. In 15 of the stroke cases, for instance, the records showed the patient had previously had a stroke but did not justify an acute stroke diagnosis at the time of the doctor’s visit. A “history of stroke” code, which OIG said typically should have been used, does not increase the plan’s payment.
The member side of the ledger. Audits like this one track what a plan collected from Medicare, while the medication and cost tracker in The Medicare Cost & Coverage Protection Kit follows what a HumanaChoice member is paying for prescriptions and care.
What the 212 enrollee-years are
The 212 figure comes from the eleventh group, which OIG calls potentially mis-keyed diagnosis codes. These are cases where a patient had several diagnoses for one condition but only a single diagnosis for an unrelated condition, a pattern that can signal a typing error. OIG gives the example of code E43, for protein-calorie malnutrition, being entered as I43, which maps to congestive heart failure and carries a different payment weight.
In its sample of 20 such cases, OIG found errors in 10. In one example, HumanaChoice submitted five codes for prostate cancer and a single code for asbestos-related lung disease that the medical reviewer could not find support for. Auditors did not examine the remaining 212 enrollee-years in this group. OIG recommended that Humana check each one against the medical records and refund any resulting overpayments.
An enrollee-year links one Medicare member to one payment year. The 212 are not people who were denied care or benefits; they are billing entries OIG believes the company should verify.
Why Humana rejected the recommendations
OIG’s four recommendations were to refund the $130.9 million, review the 212 enrollee-years, identify similar errors after the audit period and refund any overpayments, and strengthen its compliance procedures. Humana disagreed with all four and with some of the findings.
On the 212 cases, Humana said OIG had not identified which codes it believed were transposed or why. The company said neither federal regulations nor CMS guidance requires Medicare Advantage organizations to replicate OIG audits, and that it could not be expected to reproduce OIG’s review “based on the few examples” in the draft. OIG responded that it had given the company detailed enrollee-level information before issuing the draft, and that errors in half the sampled cases showed “a material pattern of incorrect submissions.” It maintained that the recommendation remains valid.
Humana also challenged OIG’s findings for 69 sampled enrollee-years, how the estimate accounted for underpayments, and OIG’s use of a 90 percent confidence interval. After reconsideration, OIG’s independent medical reviewer reversed its decision on nine enrollee-years, including one sepsis case, which reduced the errors in the final report from 187 to 178 and lowered the dollar estimate.
What happens next and what it means for members
OIG recommendations are not final. CMS decides whether to pursue an overpayment, and plans can appeal through Medicare’s risk adjustment data validation process. The $130.9 million remains an estimate, and Humana has not agreed to review the 212 cases.
For HumanaChoice members, the audit does not change benefits, premiums or coverage, and no member needs to take any action because of it. The dispute is between the company and the federal government over what Medicare paid.
The broader stakes still reach older Americans. Medicare Advantage now accounts for 44 percent of Medicare spending, and overpayments to private plans are funded from the same trust funds and beneficiary premiums that support the rest of the program. The audit also shows how diagnoses can end up in a patient’s file without clinical support. Members can ask their doctors for copies of visit notes and request corrections to anything inaccurate, a right guaranteed under federal HIPAA rules.
Members weighing their options for 2027 can compare HumanaChoice with other plans during Medicare’s Open Enrollment Period, October 15 through December 7. Those who disagree with a plan’s decision to deny a service or drug have a separate path through Medicare’s five-level appeals process.
Where a HumanaChoice member’s own costs get tracked
The fight over the overpayment estimate will play out between Humana and Medicare, but a member’s day-to-day exposure shows up in prescription bills, copays and the occasional denied request that needs a formal challenge.
The Medicare Cost & Coverage Protection Kit includes the prior-authorization appeal steps, a medication and cost tracker, the new Part D out-of-pocket cap and 51 state Medicare cost-help packs, which together cover the paperwork a plan dispute or a denial can create.
Follow the appeal steps in The Medicare Cost & Coverage Protection Kit.
This article was prepared with AI assistance and reviewed against the linked official sources.
