N.H. Rev. Stat. Ann. § 72:33
I. No person shall be entitled to the exemptions or tax credits provided by RSA 72:28, 28-b, 28-c, 29-a, 30, 31, 32, 35, 36-a, 37, 37-a, 37-b, 38-b, 39-b, 62, 66, and 70 unless the person has filed with the selectmen or assessors, by April 15 preceding the setting of the tax rate, a permanent application therefor, signed under penalty of perjury, on a form approved and provided by the commissioner of revenue administration, showing that the applicant is the true and lawful owner of the property on which the exemption or tax credit is claimed and that the applicant was duly qualified upon April 1 of the year in which the exemption or tax credit is first claimed, or, in the case of financial qualifications, that the applicant is duly qualified at the time of application. The form shall include the following and such other information deemed necessary by the commissioner:
(d) A place for the applicant's signature with a certification by the person applying that the application has a good faith basis and the facts in the application are true.
I-a. If any person, otherwise qualified to receive an exemption or credit, shall satisfy the selectmen or assessors that he or she was prevented by accident, mistake, or misfortune from filing a permanent application or amended permanent application on or before April 15 of the year in which he or she desires the exemption to begin, said officials may receive the application at a later date and grant an exemption or credit for that year; but no such application shall be received or exemption or credit granted after the local tax rate has been approved for that year.
I-b. Notwithstanding the April 15 application deadline in paragraph I, a person may apply for the tax credit for combat service under RSA 72:28-c at any point during the tax year in which the person is engaged in combat service. If the application is received and granted after the tax rate for the city or town is set, the credit shall be applied to the balance of tax payments due for that year. If a person is deemed eligible for the tax credit after taxes have been billed and paid for the tax year in which the person served, the credit shall be applied in the following year.
Source. 1947, 240:1, par. 29-d. RSA 72:33. 1969, 55:1. 1973, 544:8. 1977, 502:1. 1983, 155:8; 385:1. 1987, 325:1. 1991, 70:14. 1994, 102:2; 390:3, 8. 1995, 265:3, 20. 1996, 140:7. 1997, 281:1. 2003, 131:1; 299:6, 25, 26. 2007, 182:3, eff. April 1, 2007. 2016, 217:6, eff. Aug. 8, 2016. 2018, 151:4, 5, eff. Jan. 1, 2019.