3. Adjusted base proportions for assessment rolls completed in nineteen hundred ninety-one or thereafter.

1. (a) Current base proportions. (i) For each tax levy based upon the implementation roll and each subsequent roll, the legislative body of each approved assessing unit shall determine the current homestead and non-homestead base proportion, the current percentage and base percentage for the assessing unit and each portion included in its boundaries and such alterations made to such current base proportions made pursuant to subparagraph (iii) of this paragraph no later than the date on which it determines adjusted base proportions pursuant to this section.
2. (ii) The current base proportion shall be determined pursuant to the following formula: (1) Divide the current percentage of each class by the base percentage of such class.
3. (2) For each such class, multiply the result from clause one of this subparagraph by the local base proportion of such class.
4. (3) Sum the products obtained in clause two of this subparagraph and divide the product for each class by such sum.
5. (iii) Notwithstanding the provisions of subparagraph (ii) of this paragraph, the current base proportion of either class shall not exceed the adjusted base proportion, base proportion, or locally adjusted proportion, whichever is appropriate, of the immediately preceding year by more than five percent. Where the computation performed pursuant to subparagraph (ii) of this paragraph exceeds five percent for either class, the current base proportion of such class shall be limited to such five percent increase and such legislative body shall alter the current base proportions of the remaining class so that the sum of the current base proportions equals one.
6. (iv) Notwithstanding any other provision of law, in an approved assessing unit in the county of Suffolk and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand three - two thousand four, two thousand four - two thousand five and two thousand five - two thousand six assessment rolls, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year by more than two percent, or in the case of the two thousand five--two thousand six, two thousand six--two thousand seven, two thousand seven--two thousand eight, two thousand eight--two thousand nine, two thousand twelve--two thousand thirteen, two thousand thirteen--two thousand fourteen, and two thousand fourteen--two thousand fifteen assessment rolls, one percent. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such two percent or one percent increase whichever is applicable, and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.
7. (v) Notwithstanding any other provision of law, in an approved assessing unit in the county of Nassau and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand four assessment roll, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year by more than one percent. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.
8. (vi) Notwithstanding any other provision of law, in an approved assessing unit in the county of Nassau and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand five assessment roll, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year by more than one percent. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.
9. (vii) Notwithstanding any other provision of law, in an approved assessing unit in the county of Nassau and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand six assessment roll, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year by more than one percent. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.
10. (viii) Notwithstanding any other provision of law, in an approved assessing unit in the county of Nassau and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand seven assessment roll, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year by more than one percent. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.
11. (ix) Notwithstanding any other provision of law, in an approved assessing unit in the town of Colonie, county of Albany and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand seven assessment roll, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year by more than one percent. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.
12. (x) Notwithstanding any other provision of law, in an approved assessing unit in the county of Nassau and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand eight assessment roll, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year by more than one percent. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.
13. (xi) Notwithstanding any other provision of law, in an approved assessing unit in the county of Nassau and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand nine assessment roll, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year, by more than one percent. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.
14. (xii) Notwithstanding any other provision of law, in an approved assessing unit in the county of Nassau and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand ten assessment roll, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year, by more than one percent, provided that such approved assessing unit has passed a local law, ordinance or resolution providing therefor. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportion of either class equals one.
15. (xiii) Notwithstanding any other provision of law, in an approved assessing unit in the county of Nassau and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand eleven and two thousand twelve assessment rolls, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year, by more than one percent, provided that such approved assessing unit has passed a local law, ordinance or resolution providing therefor. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.
16. (xiv) Notwithstanding any other provision of law, in an approved assessing unit in the county of Nassau and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand thirteen roll, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year, by more than one percent, provided that such approved assessing unit has passed a local law, ordinance or resolution providing therefor. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.
17. (xv) Notwithstanding any other provision of law, in an approved assessing unit in the county of Nassau and for current base proportions to be determined by taxes based on such approved assessing unit's two thousand fourteen roll, the current base proportion of any class shall not exceed the adjusted base proportion or adjusted proportion, whichever is appropriate, of the immediately preceding year, by more than one percent, provided that such approved assessing unit has passed a local law, ordinance or resolution providing therefor. Where the computation of current base proportions would otherwise produce such result, the current base proportion of such class or classes shall be limited to such one percent increase and the legislative body of such approved assessing unit shall alter the current base proportion of either class so that the sum of the current base proportions equals one.

18. (b) For the purposes of this section, the base percentage and the current percentage of each class and for each portion shall be computed pursuant to this subdivision.

    1. (i) Base percentage. The base percentage for each class for each assessing unit and portion thereof shall be determined as follows:

       1. (1) Determine the estimated market value of each class by dividing the taxable assessed value of the real property in each class in the approved assessing unit and portion thereof appearing on the first final assessment roll for which the commissioner has established class equalization rates by the class equalization rate which was finally adopted by the commissioner for such roll. Provided, that if the homestead and non-homestead base proportions have been adjusted by the governing body of the approved assessing unit so as to reflect physical or quantity changes occurring after the filing of such final assessment roll, the commissioner shall make the same adjustments to the estimated market value of each class determined pursuant to this paragraph.
       2. (2) Determine the total estimated market value of the approved assessing unit or portion thereof by summing the estimated market value of each class.
       3. (3) Divide the estimated market value for each class by the total estimated market value of the approved assessing unit or portion thereof. Such quotient, as expressed as a percentage to at least four places to the right of the decimal point, shall be the base percentage of each class for such approved assessing unit or portion thereof.

    2. (ii) Current percentage. The current percentage for each class for each assessing unit and portion thereof shall be determined as follows:

       1. (1) Determine the estimated market value of each class by dividing the taxable assessed value of the real property in each class in the approved assessing unit and portion thereof appearing on the latest final assessment roll for which class equalization rates have been finally adopted by the commissioner by the class equalization rate which was finally adopted by the commissioner.
       2. (2) Determine the total estimated market value of the approved assessing unit or portion thereof by summing the estimated market value of each class.
       3. (3) Divide the estimated market value for each class by the total estimated market value of the approved assessing unit or portion thereof. Such quotient, as expressed as a percentage to at least four places to the right of the decimal point, shall be the current percentage of each class for such approved assessing unit or portion thereof.

19. (c) Where there was no taxable real property in a class in a portion on the base assessment roll, the local base proportion, base percentages and current percentages for such portion shall be determined as provided by this paragraph for each tax levy based upon an assessment roll filed subsequent to the assessment roll on which such property first appears.

    1. (i) The local base proportions shall be the adjusted proportions or adjusted base proportions, whichever are appropriate, determined pursuant to this section for the assessment roll on which such property first appears.

    2. (ii) The base percentage for each class shall be determined as follows:

       1. (1) For the class other than the class appearing for the first time, determine the estimated market value by dividing the taxable assessed value of the real property in the class in the portion on the final assessment roll on which the new class first appeared by the class equalization rate determined for such class in such portion on such roll.
       2. (2) For the class appearing for the first time, determine the estimated market value of such class by dividing the taxable assessed value of the real property in such class on the final assessment roll on which such class first appeared by the class equalization rate determined for such class in the approved assessing unit on such final assessment roll.
       3. (3) Determine the total estimated market value of the portion by summing the estimated market value of each class.
       4. (4) Divide the estimated market value for each class by the total estimated market value of the portion. Such quotient, as expressed as a percentage to at least four places to the right of the decimal point, shall be the base percentage of each class for such portion.
    3. (iii) Current percentages shall be determined as otherwise provided by this section, except that until the commissioner can determine a class equalization rate for the new class in such portion, the class equalization rate for the class in the approved assessing unit shall be used in lieu thereof.
20. (d) Adjusted base proportions. No later than five days subsequent to the filing of the final assessment roll, or thirty days prior to the last date prescribed by law for the first levy of taxes upon the final assessment roll, whichever is later, the legislative body of such assessing unit shall adjust such current base proportions to reflect the addition to the assessment roll of new property, additions to or improvements of existing property or formerly exempt property or the full or partial removal from the assessment roll of property by reason of fire, demolition, destruction or new exemption or any change in the class designation of any parcel of real property subsequent to the taxable status date of the latest final assessment roll for which class equalization rates have been finally adopted. The current base proportions so adjusted shall be known as the adjusted homestead and non-homestead base proportions.
21. (e) Upon determination of the adjusted homestead and non-homestead base proportions, the legislative body of such assessing unit shall within five days notify the commissioner, on forms prescribed by the commissioner, of the adjusted homestead and non-homestead base proportion as computed pursuant to paragraph (c) of this subdivision for each class applicable to such assessing unit and each portion contained therein; the assessed value of all property in each class for such assessing unit and each portion contained therein; the net change in assessed value for each class on the assessment roll resulting from the additions to or removals from the assessment roll referred to in paragraph (c) of this subdivision for such assessing unit and each portion contained therein; and the net change in assessed value for each class on the assessment roll resulting from changes other than those referred to in paragraph (c) of this subdivision for such assessing unit and each portion contained therein.
22. (f) The commissioner shall review such adjusted homestead and non-homestead base proportions for accuracy of its determination and compliance with the provisions of this subdivision. The commissioner shall complete its review no later than ninety days after the receipt of such adjusted homestead and non-homestead base proportions. The commissioner shall notify the legislative body of such approved assessing unit of any adjusted homestead and non-homestead base proportions to which it objects and the reasons therefor. A hearing shall be conducted by the commissioner within ten days after notification of such objection. The provisions of section five hundred twenty-five of this chapter shall apply so far as practicable to a hearing under this section. After the hearing, if the commissioner finds that the adjusted homestead and non-homestead base proportions have been determined incorrectly, it shall direct the local legislative body to redetermine the adjusted homestead and non-homestead base proportions in compliance with its findings.
23. (g) If the legislative body of the approved assessing unit discovers that a mathematical error was made in the determination of the adjusted homestead and non-homestead base proportions, or is directed by the commissioner after a hearing to redetermine the adjusted homestead and non-homestead base proportions, it shall redetermine the adjusted homestead and non-homestead base proportions prior to the levy of taxes for that fiscal year. If the redetermination cannot be made prior to the extension of taxes for that fiscal year, the tax levying body shall adjust the tax levy for the ensuing fiscal year to account for the improper apportionment of taxes which resulted from the error in the determination of the adjusted homestead and non-homestead base proportions, upon notice to the commissioner.
24. (h) Where there is a new portion that did not appear on the base assessment roll, the local base proportion, base percentages and current percentages for each class in such portion shall be determined as provided in paragraph (c) of this subdivision for a new class in a portion.

(c) Each such officer shall allocate, to the homestead class of such portion, a share of the tax levied on such portion in accordance with the other applicable provisions of law equal to such homestead base proportion, adjusted homestead base proportion, or locally-adjusted homestead proportion. The remainder of such levy shall be allocated to the non-homestead class utilizing the non-homestead base proportion, non-homestead adjusted base proportion, or locally-adjusted non-homestead proportion, as appropriate.

1. (i) For taxes levied based on assessment rolls completed prior to nineteen hundred eighty-nine, unless a new locally-adjusted homestead proportion and locally-adjusted non-homestead proportion is certified to such an officer by such governing body, in any year in which the commissioner certifies to such an officer an adjusted homestead base proportion and adjusted non-homestead base proportion, such officer shall use such adjusted homestead base proportion and adjusted non-homestead base proportion thereafter for the purposes of this section until a new adjusted homestead base proportion and adjusted non-homestead base proportion are so certified.
2. (ii) If, in the year nineteen hundred eighty-nine, the commissioner certifies adjusted homestead base proportions and adjusted non-homestead base proportions, the governing body of the approved assessing unit may, for tax levies based upon assessment rolls completed and filed in nineteen hundred eighty-nine or nineteen hundred ninety, use such adjusted homestead and non-homestead base proportions for the purposes of this paragraph, or alternatively, such body may use the homestead and non-homestead base proportions, the locally adjusted homestead and non-homestead proportions or the adjusted homestead and non-homestead base proportions, whichever is appropriate, used for the immediately preceding tax year.
3. (iii) For taxes levied based on assessment rolls completed and filed in nineteen hundred ninety-one and thereafter, the officer shall use such base proportions, adjusted homestead and non-homestead base proportions or locally adjusted homestead and non-homestead proportions as are certified to him in that year by the legislative body of the approved assessing unit, pursuant to the requirements of this section.
4. 7. Annual certification by approved assessing units. The governing body of any approved assessing unit, other than a village, which has adopted the provisions of this section shall certify annually to the school authorities of each school district which contains such assessing unit or a portion thereof that the local law adopting the provisions of this section is in effect. Such certification shall set forth the homestead and non-homestead base proportions established for the school district portion, the adjusted homestead and non-homestead base proportions or, if locally adjusted homestead and non-homestead proportions have been established for such portion, such locally adjusted homestead and non-homestead proportions, whichever is applicable. Such certification shall be made at the same time as the delivery of the current assessment roll to such school district.
5. 8. Placing on or removal from assessment roll. Nothing in this section shall prevent placing on the assessment roll new property, additions to or improvements of existing property or formerly exempt property or the full or partial removal from the roll of property by reason of fire, demolition, destruction or new exemption.
6. 9. Rescission. The governing body of any approved assessing unit or eligible non-assessing unit village which has adopted the provisions of this section may by local law without referendum, no later than the last date prescribed by law for the levy of taxes upon an assessment roll to which it would otherwise be applicable, determine that the provisions of this section shall no longer apply to any subsequent levies on its assessment roll. A copy of such local law shall be provided to the municipal corporations, bodies and officers receiving copies of local laws enacted pursuant to subdivision one of this section.
7. 10. Determination. The determination of inclusion within or exclusion from the homestead class or non-homestead class for purposes of this section shall be subject to administrative and judicial review as provided by law for review of assessments.