The Medicare 'fee-for-service' (FFS) recovery audit program means that RACs are paid on a contingency-fee basis to perform audits. In other words, while they are going to perform post payment review and are working on identifying improper payments, they are financially-incentivized from Medicare to identify overpayments, and they have no direct financial incentive to award underpayments to providers.
During the 2015 fiscal year, RACs collected nearly $360 million in overpayments while awarding just $81 million in underpayments to Medicare. From 2010 to 2015, RAC audits have resulted in liability of more than $8.9 billion for providers nationwide.