The American Recovery and Reinvestment Act (Recovery Act), enacted on February 17, 2009, appropriated $275 billion to be distributed for federal contracts, grants, and loans. As of March 25, 2011, $191 billion of this $275 billion had been paid out. GAO was asked to determine if Recovery Act contract and grant recipients have unpaid federal taxes and, if so, to (1) determine, to the extent possible, the magnitude of known federal tax debt which is owed by Recovery Act contract and grant recipients; and, (2) provide examples of Recovery Act contract and grant recipients who have known unpaid federal taxes. To determine, to the extent possible, the magnitude of known tax debt owed by Recovery Act contract and grant recipients, GAO identified contract and grant recipients from www.recovery.gov and compared them to known tax debts as of September 30, 2009, from the Internal Revenue Service (IRS). To provide examples of Recovery Act recipients with known unpaid federal taxes, GAO chose a nonrepresentative selection of 30 Recovery Act contract and grant recipients, which were then narrowed to 15 based on a number of factors, including the amount of taxes owed and the number of delinquent tax periods. These case studies serve to illustrate the sizable amounts of taxes owed by some organizations that received Recovery Act funding and cannot be generalized beyond the cases presented. This report contains no recommendations.