The OIG has issued a report entitled "Concerns With Rebates in the Medicare Part D Program." According to the OIG, Medicare Part D drug plan sponsors underestimated manufacturer rebates in 69% of their bids for plan year 2008, which can lead to increased beneficiary premiums. The OIG also discusses rebates associated with encouraged use of certain drugs, the transparency of plan sponsor relationships with their pharmacy benefit managers (PBMs), and how PBM fees received from manufacturers are reported. In response to its findings, the OIG recommends that CMS: require sponsors to more accurately include expected rebates in their bids, require sponsors to use methods CMS deems reasonable to allocate rebates across plans, provide sponsors with sufficient audit rights and access to rebate information, and ensure that sponsors appropriately report fees that PBMs collect from manufacturers. CMS disagreed with certain aspects of the recommendations.