HUD reviews QCTs as new data become available or when metropolitan area definitions change.  The statute directs HUD to use census data to determine tract eligibility.  Current designations are based on data from the 2000 Census.  In the past, tract-level data was only available from the Decennial Census.  Thus, QCTs were reviewed as Decennial Census data became available.  However, due to changes in collection of income data at the tract level by the Census Bureau, HUD will now be relying on data from the American Community Survey (ACS).  Although the ACS is an annual survey, tract-level data from the ACS will be released as five-year averages.  The first release of this data will cover the 2005 through 2009 period and the Census Bureau expects to make this data available in late 2010 or early 2011.  HUD anticipates that it will review QCTs using the new data during 2011 for an effective date of January 1, 2012.  QCTs will subsequently be reviewed based on new data every 5 years.