N.Y. RPT Law § 402

§ 402. United States or state property held under contract of sale.\n1. Whenever the legal title of real property is in the United States,\nor in the state of New York, but the use, occupation or possession\nthereof is in a person, partnership, association or corporation under a\ncontract of sale or other agreement whereby a right to acquire the\npremises through an option, a first privilege or a first refusal is\ngranted, or whereby upon one or more payments the legal title thereto is\nto be or may be acquired by such person, partnership, association or\ncorporation, his or its interest in such real property shall be assessed\nand taxed as real property and shall be entered in the assessment roll\nin the same manner as if such person, partnership, association or\ncorporation held the legal title to such property, except for the\naddition to the description of the words "interest under contract",\n"interest under option", or other appropriate words descriptive of the\ninterest in the property so assessed. Such assessment shall be at the\nfull value of such interest.\n 2. The assessors shall add to the assessment roll opposite the\ndescription of any such interest a notation stating that the real\nproperty itself so owned by the United States, or by the state, is not\nto be taxed. Every notice of sale or other process and every conveyance\nor other instrument affecting the title to any such property, consequent\nupon the non-payment of any such tax, shall contain a statement that\nsuch legal title is not sold or to be sold or affected.\n 3. The classification of such interest as real property for the\npurposes of taxation under this chapter shall not be affected by any\nprovision of the contract or agreement under which the same is held.\n