Conn. Gen. Stat. § 9-40a

(b) Not later than May first in each year in which a canvass of electors is conducted, the registrars of voters shall send the notice of removal and return card required by the National Voter Registration Act of 1993, P.L. 103-31, as amended from time to time, to each member of the armed forces of the United States or their auxiliaries, or a spouse or dependent of such member, whose name has not been checked as having voted in at least one election, primary, referendum or town meeting during the four preceding calendar years. If such elector does not return the card within thirty days, the registrars of voters shall place the name of such elector on the inactive registry list compiled under section 9-35 for four years, and if such name remains on the inactive list for four years, such name shall thereupon be removed from the registry list. Such removal shall not affect the right of such member, spouse or dependent to apply for admission as an elector in such town.