N.Y. Real Property Tax Law § 485-F
3.
(a) The "exemption base" shall be the extent of the increase in assessed value attributable to such alteration, construction, installation, or improvement as determined in the initial year for which application for exemption is made pursuant to this section, except as provided in subparagraph (ii) of this paragraph.
(b) No exemption shall be granted pursuant to this section, unless: