N.Y. Comp. Codes R. & Regs. tit. 9, § 2502.7 – Rent adjustments upon vacancy or succession.

(a) The legal regulated rent for any vacancy lease entered into after June 15, 1997 shall be as hereinafter provided in this subdivision. The previous legal regulated rent for such housing accommodation shall be increased by the following:
1. (1) if the vacancy lease is for a term of two years, 20 percent of the previous legal regulated rent; or
2. (2) if the vacancy lease is for a term of one year, the increase shall be 20 percent of the previous legal regulated rent less an amount equal to the difference between:
  1. (i) the two year renewal lease guideline promulgated by the rent guidelines board of the county in which the housing accommodation is located, applied to the previous legal regulated rent; and
  2. (ii) the one year renewal lease guideline promulgated by the rent guidelines board of the county in which the housing accommodation is located, applied to the previous legal regulated rent. In addition, if the legal regulated rent was not increased with respect to such housing accommodation by a permanent vacancy allowance within eight years prior to a vacancy lease executed on or after June 15, 1997, the legal regulated rent may be further increased by an amount equal to the product resulting from multiplying such previous legal regulated rent by six-tenths of one percent and further multiplying the amount of rent increase resulting therefrom by the greater of: All such increases shall be in lieu of any allowance authorized for the one or two year renewal component of the guideline promulgated by the rent guidelines board of the county in which the housing accommodation is located, but shall be in addition to any other increases authorized pursuant to the act and this Subchapter, including adjustments pursuant to section 2502.4(a) of this Part, and any applicable vacancy allowance authorized by the rent guidelines board.
    1. (a) the number of years since the imposition of the last permanent vacancy allowance; or
    2. (b) if the rent was not increased by a permanent vacancy allowance since the housing accommodation became subject to the act and this Subchapter, the number of years that such housing accommodation has been subject to the act and this Subchapter. Provided that if the previous legal regulated rent was less than $300, the total increase shall be as calculated above, plus $100 per month. Provided further, that if the previous legal regulated rent was at least $300 and no more than $500, in no event shall the total increase pursuant to this subdivision be less than $100 per month.
3. (3) Effective June 24, 2011, the increase authorized in this paragraph may not be implemented more than one time in any calendar year, notwithstanding the number of vacancy leases entered into in such year.
(b) Any provision of this Subchapter to the contrary notwithstanding, where all tenants named in a lease have permanently vacated a housing accommodation, and a primary-resident family member of such tenant or tenants (first successor) is entitled to and executes a renewal lease for the housing accommodation, as provided in section 2503.5 of this Title, and thereafter permanently vacates the housing accommodation, if such housing accommodation continues to be subject to the act and this Subchapter after such first successor vacates, and a primary-resident family member (second successor) is entitled to and executes a renewal lease for the housing accommodation, as provided in section 2503.5 of this Title, the legal regulated rent shall be increased by a sum equal to the allowance then in effect for vacancy leases, including the amount allowed by subdivision (a) of this section. Such increase shall be in addition to any other increases provided for in the act and this Subchapter, including adjustments pursuant to section 2502.4(a) of this Part, and any applicable vacancy allowance authorized by the rent guidelines board of the county in which the housing accommodation is located, and shall be applicable in like manner to the renewal lease of each second subsequent succeeding family member.