N.Y. RPT Law § 1803

§ 1803. Base proportions and adjusted proportions; determinations. 1.\nBase proportion. The legislative body of each special assessing unit\nshall establish the base proportion for each class and a base proportion\nfor each class for each portion and each town and county special\ndistrict and zone of assessment included within its boundaries.\n 2. Adjusted proportions. (a) For assessment rolls prepared during and\nafter nineteen hundred eighty-two and before nineteen hundred\nninety-one, and for assessment rolls prepared after two thousand one for\npurposes of all county and town special districts and zones of\nassessment, the legislative body of each special assessing unit shall\nadjust such base proportions to reflect the addition to the assessment\nroll of new property, additions to or improvements of existing property\nor formerly exempt property or the full or partial removal from the roll\nof property by reason of fire, demolition, destruction or new exemption\nor any change in the class designation of any parcel of real property;\nprovided, however, that the legislative body of each special assessing\nunit may further alter the base proportions, as so adjusted, in\naccordance with the provisions of paragraph (b) of this subdivision.\n (b) Any further such alterations for any class in any year may not\nexceed five percent of the base proportions or adjusted proportions used\nfor the immediately preceding tax levy, provided that in each year the\nsum of any such proportions for such special assessing unit or portion\nthereof, or town or county special district or zone of assessment\nincluded therein, shall equal one. Such alterations may vary among\nportions and among town and county special districts; provided, however,\nthat for town and county special districts and zones of assessment, any\nsuch alterations shall not be inconsistent with any changes in the value\nof the class in the special district as indicated by the assessed value\nof the class in the special district and the most relevant class\nequalization rates certified by the commissioner pursuant to section\ntwelve hundred twelve of this chapter.\n 3. Town and county special districts. For purposes of town and county\nspecial districts that are not portions, the base proportion shall be\ndetermined by using the final assessment roll filed in calendar year two\nthousand one. The base proportion of a zone of assessment established\nfrom the territory of a prior district, as such term is defined in\nparagraph (f) of subdivision one of section four of chapter six hundred\neighty-five of the laws of two thousand three, shall be determined by\nusing the base proportion of the prior district with such adjustments,\nif any as are required by paragraph a of subdivision two of this\nsection.\n