The 2014 OIG Work Plan includes the following: 

"Policies and Practices. We will determine the impact of subordinate facilities in hospitals billing Medicare as being hospital based (provider based) and the extent to which such facilities meet CMS’s criteria. Context—Provider-based status allows a subordinate facility to bill as part of the main provider. Provider-based status can result in additional Medicare payments for services furnished at provider-based facilities and may increase beneficiaries’ coinsurance liabilities. In 2011, the Medicare Payment Advisory Commission (MedPAC) expressed concerns about the financial incentives presented by provider-based status and stated that Medicare should seek to pay similar amounts for similar services. (OEI; 04-12-00380; 04-12-00381; expected issue date: FY 2014; work in progress)