A photo of dollar bills falling from skyJust last month, I wrote about how the government was falling short in its job to collect hundreds of millions of dollars in Medicaid overpayments. That news came from a report released by the Department of Health and Human Services’ Office of the Inspector General.

The saga continues with another report from the Government Accountability Office which finds that insurers that offer Medicare Advantage plans received up to $5.1 billion in overpayments between 2010 and 2012. These plans are offered by private companies that contract with Medicare to provide both Part A and Part B benefits.

The GAO audit is critical of how the Centers for Medicare and Medicaid Services (CMS) calculated payment rates for Medicare Advantage plans.  It notes that the plans are incentivized to adjust the risk scores for private Medicare beneficiaries versus public fee-for-service patients.

The report found the following:

GAO estimated that cumulative Medicare Advantage (MA) risk scores in 2010 were 4.2 percent higher than they likely would have been if the same beneficiaries had been enrolled continuously in Medicare fee-for-service (FFS). For 2011, GAO estimated that differences in diagnostic coding resulted in risk scores that were 4.6 to 5.3 percent higher than they likely would have been if the same beneficiaries had been continuously enrolled in FFS. This upward trend continued for 2012, with estimated risk scores 4.9 to 6.4 percent higher.

While CMS did not change its risk score adjustment methodology for 2013, agency officials said they may revisit their methodology for future years.

Click here to read the full report.