The FEHB and the federal retirement programs “are by definition susceptible to significant improper payments,” an IG audit has said, adding that overpayments are much more common than underpayments in each.

The audit, one of a series by IGs across government on improper payments, found that in 2016, out of a total retirement program outlay of more than $82 billion, there were improper payments of $304 million, or just 0.37 percent. However, of that total, $237 million constituted overpayments wile underpayments accounted for just $67 million.

Similarly, in the FEHB program’s outlay of nearly $50 billion, just 0.19 percent, $97 million, was improper. But of that total, all but $1 million was overpayments.

It added that OPM was more successful in recovering retirement overpayments than health insurance overpayments–it collected nearly $204 million of the $224 million targeted for the former but just $40 million of the $96 million targeted for the latter.