N.H. Rev. Stat. Ann. § 266:7

The director shall have authority, through his duly authorized agents, to inspect any motor vehicle used for the purpose of transporting school children to any school to determine its fitness for such purpose, and if he finds that such vehicle is unfit, he may refuse to permit it to be designated as a school bus or student transportation vehicle. Said inspection shall be made before any motor vehicle transporting school children to any school is used for said transportation. The director shall cause to be issued some identification if such vehicle is approved as a school bus or school transportation vehicle.