N.Y. Comp. Codes R. & Regs. tit. 14, § 251.3
(2) This subdivision shall not be construed to require the extension of any employment beyond the time at which it would otherwise terminate by operation of law, rule or regulation.
(b) Successive leaves of absence.
Where a leave of absence without pay has been granted for a period which aggregates two years, or more if extended pursuant to subdivision (a) of this section, a further leave of absence without pay shall not be granted unless the employee returns to his/her position and serves continuously therein for six months immediately preceding the subsequent leave of absence.
(a) Leave of absence; duration.