The New Jersey Constitution of 1947 (Annotated) Art. VIII, § I, ¶ 6

6. The Legislature may enact general laws under which municipalities may adopt ordinances granting exemptions or abatements from taxation on buildings and structures in areas declared in need of rehabilitation in accordance with statutory criteria, within such municipalities and to the land comprising the premises upon which such buildings or structures are erected and which is necessary for the fair enjoyment thereof. Such exemptions shall be for limited periods of time as specified by law, but not in excess of 5 years.