N.H. Rev. Stat. § 659:101
The absentee ballot affidavits and application forms processed by the moderator as provided in RSA 659:50, the absentee ballots challenged and rejected as provided in RSA 659:51 and RSA 659:53, and the qualified voter affidavits as provided in RSA 654:12 and any other documentary proof of qualifications retained by the town or city clerk, the supervisors of the checklist, or other election official shall be preserved in accordance with RSA 33-A:3-a. Qualified voter and voter registration affidavits shall be retained for the period set forth in RSA 33-A:3-a, and other materials may be destroyed after the election is settled and all appeals have expired or one year after the election, whichever is longer.
RSA 659:101
1979, 436:1. 2003, 289:59. 2006, 94:3. 2009, 278:6. 2010, 317:83, eff. Aug. 16, 2010 at 12:01 a.m. 2017, 205:14, eff. Sept. 8, 2017.