N.Y. Comp. Codes R. & Regs. tit. 4, § 73.1
(c) The term employee means any person in the service of an employer, except:
(1) any person whose regular work schedule is less than 20 hours a week, other than:
(e) The term post retiree shall mean a person who has become enrolled in the plan as an employee and whose coverage is being continued after his withdrawal from the active service of the employer under the eligibility privileges of the plan and who either:
(h) The term dependent shall include the spouse of an employee or retired employee. It shall also include such person's unmarried child under 19 years of age, any unmarried child 19 years of age or older who is incapable of self-support by reason of mental or physical disability and who became so incapable before reaching the age at which dependent coverage would otherwise terminate, and any student dependent as hereinafter defined. The term child shall be deemed to include any natural born child, any legally adopted child and any stepchild dependent upon the employee or retired employee, any child dependent upon the employee or retired employee during any waiting period prior to the finalization of the child's adoption by the employee or retired employee, and any child chiefly dependent on the employee or retired employee and permanently residing in the household of the employee or retired employee. Dependent shall not include, however:
(i) The term student dependent means an employee's or retired employee's unmarried child 19 years of age or older but not yet 25 years of age; provided, however, that the time spent on military duty as defined in paragraph (b) of subdivision 1 of section 243 of the Military Law, not to exceed four years, shall be subtracted from the age of such child for purposes of determining the maximum age for eligibility as a student dependent who: