This report from Milliman Inc. explores the effects that the Affordable Care Act will have on Medicare Advantage (MA). For example, beginning in 2012, Medicare Advantage organizations' reimbursement policy will change substantially, mimicking the expected fee-for-service costs of the county in which the MA organization is located.

From the report:

Medicare Advantage is a federal program in which health insurance organizations provide medical benefits to Medicare eligibles. In exchange for providing their enrollees with at least traditional Medicare benefits, the MA organization receives revenue from the Centers for Medicare and Medicaid Services (CMS). In addition, some organizations may require an enrollee premium (in addition to Medicare's Part B premium) if the CMS revenueis not projected to be sufficient to cover the cost of the plan's benefits and administration plus profit. The plans typically offer benefit enhancements in the form of reduced cost sharing or coverage of benefits that traditional Medicare does not cover. As of September 2010, about 25% of the Medicare population was enrolled in a Medicare Advantage plan.

Full Report: Payment Reform will Impact Medicare Advantage (PDF | 175 KB) 

Milliman, Inc. (2011). Payment reform will impact Medicare Advantage. Dunks, P., Goetsch, E., and Piper, B.