New York Application-Partial Tax Exemption For New Multiple Dwellings is a program that allows new multiple dwellings to receive a partial tax exemption. This exemption applies to both real estate taxes and any applicable mortgage recording taxes. The application must be filed with the New York State Department of Taxation and Finance for the property to be eligible for the tax exemption. There are two types of New York Application-Partial Tax Exemption For New Multiple Dwellings: 421-a and J-51. 421-a is an exemption for new multiple dwellings built between January 1, 1974, and June 15, 2019, that are used for residential purposes and are located in certain New York City neighborhoods. Under the 421-a program, the property owner receives a partial tax exemption for a period of 10 to 25 years. J-51 is an exemption for new multiple dwellings built or substantially renovated after January 1, 1974. This program provides a partial tax exemption for a period of 10 to 25 years for new multiple dwellings that are used for residential purposes and that have received certain property improvements.