(a) System or retirement system shall mean the New York State Teachers’ Retirement System.

(b) Plan year shall mean the fiscal year of the system of July 1-June 30.

(c) Tier 1 member shall mean a member of the system with a date of membership prior to July 1, 1973, whose benefits are determined pursuant to the provisions of article 11 of the Education Law.

(d) Tier 2 member shall mean a member of the system with a date of membership on or after July 1, 1973, but before July 27, 1976, whose benefits are determined pursuant to the provisions of article 11 of the Education Law subject to the provisions of article 11 of the Retirement and Social Security Law.

(e) Tier 3 member shall mean a member of the system with a date of membership on or after July 27, 1976, but before September 1, 1983, whose benefits are determined pursuant to the provisions of article 14 of the Retirement and Social Security Law.

(f) Tier 4 member shall mean a member of the system with a date of membership on or after September 1, 1983, but before January 1, 2010, whose benefits are governed by the provisions of article 15 of the Retirement and Social Security Law.

(g) Tier 5 member shall mean a member of the system with a date of membership on or after January 1, 2010, but before April 1, 2012, whose benefits are determined pursuant to the provisions of article 15 of the Retirement and Social Security Law as amended by chapter 504 of the Laws of 2009.

(h) Tier 6 member shall mean a member of the system with a date of membership on or after April 1, 2012, whose benefits are determined pursuant to the provisions of article 15 of the Retirement and Social Security Law as amended by chapter 18 of the Laws of 2012.