421-g was the previous New York State property tax incentive program that encouraged the conversion of older office and commercial buildings into housing in Lower Manhattan. 421-g was enacted in 1995 and applied to eligible buildings south of Murray Street, excluding Battery Park City. Under the 421-g program, qualifying conversion projects received property tax exemptions and abatements that helped make residential redevelopment financially feasible. 421-g supported the conversion of millions of square feet of office space in a tax friendly environment. Although tax benefits for some completed 421-g projects continued until 2024, the 421-g program stopped accepting new projects years earlier and was not available to current developments. The 421-g program is now considered a historical predecessor to newer office-to-residential conversion incentive programs, including 467-m. (New York Real Property Tax Law 421-g, New York State Senate, Verified June 2026)