The Department of Housing and Urban Development (HUD) Quality Control for Rental Assistance Subsidy Determinations (HUDQC) Study provides national estimates of the extent, severity, costs, and sources of rent errors in tenant subsidies for the largest housing programs administered by the Office of Housing and the Office of Public and Indian Housing (PIH). These programs account for nearly all of HUD’s current housing assistance outlays administered by the Office of Housing and PIH, as well as the large majority of units assisted by HUD. This study was designed to measure the extent of administrator income and rent determination error by housing providers. It does not involve an audit of individual Public Housing Authorities (PHAs) or projects, nor does it monitor the implementation of housing programs. Its singular focus is to identify households for which an error was made in the calculation of the amount of the household’s rent and to provide nationally representative findings related to those errors.