Every year the U.S. Department of Health and Human Services’ Office of the Inspector General (OIG) examines the operations of various department offices, programs, and policies and offers recommendations for changes and improvements.  Some of those recommendations are adopted and others are not.
The OIG annually publishes a document reiterating what it believes to be its most important and potentially useful recommendations that were not adopted, and that publication was just released.
Among the Medicare and Medicaid recommendations it has presented again are:

• Establish accurate and reasonable Medicare payment rates for hospital inpatient services.
• Establish accurate and reasonable Medicare payment rates for hospital transfers.
• Reduce hospital outpatient department payment rates for ambulatory surgical center-approved procedures.
• Prevent inappropriate payments to Medicare home health agencies.
• Reduce inappropriate payments to skilled nursing facilities.
• Prevent payments for ineligible Medicare beneficiaries.
• Reconcile Medicare outlier payments in accordance with federal guidance and regulations.
• Ensure that states calculate accurate costs for Medicaid services provided by local providers.
• Ensure the collection of identified Medicare overpayments.
• Improve oversight of management of Medicaid personal services.
• Improve the Medicare appeals process at the administrative law judge level.
• Enhance efforts to identify adverse events to ensure quality of care and safety.
• Ensure that Medicare children receive all required preventive screening services.
• Strengthen oversight of state access standards for Medicaid managed care.

In its Compendium of Unimplemented Recommendations/March 2015, the OIG presents the issues and its rationale for its recommendation and describes the status of implementation, including, in some cases, why CMS has chosen not to implement its recommendations.
Find the report here.