N.Y. RPT Law § 400

§ 400. United States. 1. Real property owned by the United States\nshall be exempt from taxation, except as otherwise provided by the laws\nof the United States.\n 2. Real property occupied exclusively or in part by the United States\npursuant to the provisions of the public buildings purchase contract act\nof nineteen hundred fifty-four (Public Law 519, 83rd Congress) shall be\nexempt from taxation and exempt from special ad valorem levies and\nspecial assessments to the extent provided in section four hundred\nninety of this chapter, during the period that the United States is\nrequired to make reimbursement for taxes payable on such property,\nprovided that the United States enters into an agreement or agreements\nwith the municipal corporation or corporations in which such properties\nare located, whereby it will undertake to pay a fair and reasonable sum\nannually on such property as taxes. Where a part of the property is so\noccupied by the United States, such part only shall be exempt and the\nremainder thereof shall be subject to taxation, special ad valorem\nlevies and special assessments. The sums received by any municipal\ncorporation pursuant to this subdivision shall be devoted to purposes to\nwhich taxes may be applied.\n