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Federal Auditors Find Most Sampled Medicare Advantage Diagnosis Codes From Gateway Health Plan Lacked Medical Record Support
An OIG compliance audit found that 232 of 286 sampled enrollee records from a Pennsylvania Medicare Advantage plan did not support the diagnosis codes submitted to CMS for federal payment calculations.
By the Goodsurance editorial teamAugust 7, 2026
The Department of Health and Human Services Office of Inspector General released a compliance audit of Gateway Health Plan, a Medicare Advantage organization operating under contract H5932, as part of a continuing series examining whether plans accurately submit diagnosis codes to CMS for risk adjustment.
For 232 of 286 sampled enrollee-years, medical records did not support the diagnosis codes submitted, resulting in 830,334 dollars in net overpayments from the sample reviewed. The OIG recommended that Gateway refund estimated overpayments to the federal government and improve internal procedures for preventing and detecting high-risk miscoding.
More than 80 percent of sampled Medicare Advantage diagnosis codes from one plan had no medical record to back them up, a federal audit found.
The risk adjustment system uses diagnosis codes submitted by plans to set monthly payments from CMS to each Medicare Advantage organization. When codes are not supported by clinical documentation, the resulting payments exceed what the program would otherwise pay, drawing down Medicare Trust Fund resources.
CMS acknowledged the findings and indicated it would pursue repayment through standard audit reconciliation. Gateway was encouraged to review its compliance procedures for the specific high-risk diagnosis categories that auditors flagged.
This individual-plan audit is part of a broad OIG initiative covering dozens of Medicare Advantage insurers. Aggregate overpayments linked to unsupported diagnosis codes across all plans have been estimated in prior government reports at tens of billions of dollars annually across the program.
In plain words
A federal watchdog agency checked billing records for a Medicare Advantage plan called Gateway Health Plan. The plan sent medical codes to the government showing how sick its patients were. The government uses those codes to decide how much to pay the plan each month. Most of the codes the auditors checked did not match what was in the patients' medical records. This led to the plan being overpaid by about 830,000 dollars just from the cases that were reviewed. The watchdog told the plan to pay the money back and fix its record-keeping.
Understand the basics first
Source: HHS Office of Inspector General
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