Answer

The New York City Department of Finance maintains a list of properties with a 421a exemption, and the NYC Department of Housing Preservation & Development (HPD) provides overviews of the rules and procedures associated with the program. New York City website addresses frequently change, so a basic web search for these agencies should be useful as well.

The NYU Furman Center also provides access to data on properties participating in various incentive programs, including 421a, on their CoreData.nyc site. Users can filter by subsidy type and program in the Subsidized Housing Database withing the CoreData mapping tool to identify participating properties.

For a primer on the program, a reference text is available at the Jack Brause Library, located at NYU Midtown Center, 11 W. 42nd St, Suite 510: City of New York Department of Housing Preservation and Development Office of the Commissioner Division of Tax Programs and Policy: Chapter 6 Tax Exemption Pursuant to 421-a of the Real Property Tax law on 11-245 of the Administrative Code of the City of New York.