Conn. Gen. Stat. § 9-153d

(b) Within the time limits in subsection (b) of section 9-158c for availability of overseas ballots, either registrar of voters may, in a form to be prescribed by the Secretary of the State, direct the municipal clerk forthwith to mail an overseas ballot, with the necessary envelopes and instructions, to the best-known address, within the knowledge of the registrar issuing such direction, of a citizen of the United States who is eligible to vote as an overseas elector under sections 9-158a to 9-158m , inclusive, and such direction shall constitute sufficient application for such absentee ballot. Such ballot shall not be counted unless an application form prescribed in subsection (b) of section 9-158d is received by the town clerk prior to the day of the election or primary. The municipal clerk may, during such period, so act on his own motion and without waiting for the direction of a registrar of voters or other application, if the clerk first completes and retains in his records as an application the same direction form that is used by a registrar of voters.

See Sec. 9-153e re alternate application procedure for certain military personnel.