N.H. Rev. Stat. Ann. § 198:20

Whenever a nonpublic school, or a portion thereof, closes and any of its pupils become enrolled in the public schools, the state board in determining eligibility for any form of state aid computed wholly or in part on the basis of average daily membership of pupils may count these newly enrolled pupils as though they had been in average daily membership at the public schools of the district during the preceding school year.