N.H. Rev. Stat. Ann. § 193-E:3-f

The principal or other administrator of a high school shall grant credit toward high school graduation for similar courses and programs that have been satisfactorily completed at other approved schools or shall provide reasonable justification for denial. For purposes of this section, approved schools include all New Hampshire public schools, including chartered public schools, public academies, approved public or private tuition program schools, and all schools in Vermont and Maine that are members of an interstate school district with schools in New Hampshire.