N.Y. Real Property Tax Law § 1805
1. The assessor of any special assessing unit shall not increase the assessment of any individual parcel classified in class one in any one year, as measured from the assessment on the previous year's assessment roll, by more than six percent and shall not increase such assessment by more than twenty percent in any five-year period. The first such five-year period shall be measured from the individual assessment appearing on the assessment roll completed in nineteen hundred eighty; provided that if such parcel would not have been subject to the provisions of this subdivision in nineteen hundred eighty had this subdivision then been in effect, the first such five-year period shall be measured from the first year after nineteen hundred eighty in which this subdivision applied to such parcel or would have applied to such parcel had this subdivision been in effect in such year. If, in respect to any individual parcel classified in class one on the assessment roll completed and applicable for the year nineteen hundred eighty-two, the assessment for the year nineteen hundred eighty-one exceeds by more than twenty percent the assessment for the year nineteen hundred eighty, such assessor shall compute the actual assessments to be entered on assessment rolls applicable to the years nineteen hundred eighty-two through nineteen hundred ninety as follows:
2. The assessment roll of a special assessing unit wholly contained within a city shall identify those parcels classified in class two which have fewer than eleven residential units. The assessor of any such special assessing unit shall not increase the assessment of any parcel so identified in any one year, as measured from the actual assessment on the previous year's assessment roll, by more than eight percent and shall not increase such assessment by more than thirty percent in any five-year period. The first such five-year period shall be measured from the individual assessment appearing on the assessment roll completed in nineteen hundred eighty-one provided that, if such parcel would not have been subject to the provisions of this subdivision in nineteen hundred eighty-one had this subdivision then been in effect, the first such five-year period shall be measured from the first year after nineteen hundred eighty-one in which this subdivision applied to such parcel or would have applied to such parcel had this subdivision been in effect in such year. If, in respect to any parcel so identified on the assessment roll completed and applicable for the year nineteen hundred eighty-four, the actual assessment for the year nineteen hundred eighty-three exceeds by more than thirty percent the assessment for the year nineteen hundred eighty-one, such assessor shall compute the actual assessments to be entered on assessment rolls applicable to the years nineteen hundred eighty-four through nineteen hundred ninety-two as follows: