The CMS has collected more than $313 million in Medicare overpayments through its recovery audit program since October 2009, according to the CMS' most recent recovery-audit report (PDF)—and nearly half of that was collected from January through March of this year.

The CMS collected $162 million in overpayments through the first three months of 2011, as compared with $75.8 million from October to December 2010 and $75.4 million from October 2009 to September 2010. Top overpayment issues involved incorrect coding, as in the case of improperly calculated patient ventilation hours, and billing for bundled services separately.

The CMS also has returned $52.6 million in underpayments since 2009: $22.6 million from January through March 2011, $13.1 million from October to December 2010 and $16.9 million from October 2009 to September 2010.

The Tax Relief and Health Care Act of 2006 made the CMS' recovery audit program permanent, according to the CMS' website, and mandated that the program be expanded to all 50 states by 2010. Four recovery auditors are charged with identifying overpayments and underpayments in their respective regions.