A new report from the NYU Furman Center provides a detailed picture of the housing produced under the contentious 421-a tax exemption, including how trends shifted when the program was last reauthorized. The Data Brief shows the exemption was used for 68 percent of all completed new housing in buildings of four or more units across the city between 2010 and 2020. More than 117,000 units qualified for the tax break during the period studied, with production peaking between 2017 and 2018.