N.Y. Comp. Codes R. & Regs. tit. 11, § 360.3
(a) No insurer may restrict or limit eligibility for individual or small group policies except in the following ways:
(1) Insurers may issue policies only to or through groups recognized under sections 4235(c)(1)(A), (B), (D), (H), (K), (L) and (M) and 4237 of the Insurance Law.
(9) Where an eligible employee or member or dependent or spouse of such employee or member rejects initial enrollment in a group or blanket policy that provides hospital, surgical or medical expense insurance, rules may be established limiting future enrollment to specified time periods, however, such rules shall not apply to such employee, member, dependent or spouse if: