N.H. Rev. Stat. § 23:23

I. A county may, by vote of the county convention, establish a county public safety revolving fund for the provision of public safety services by county employees outside of the ordinary detail of such persons, including but not limited to public safety services in connection with special events, highway construction, and other construction projects, or for any other public safety purpose deemed appropriate by the county sheriff. II. If a county establishes a county public safety revolving fund for the purposes identified in paragraph I, it shall deposit into the fund all or any part of the revenues from fees, charges, or other income derived from the activities or services supported by the fund to replenish the fund to the original appropriated amount. The county shall deposit any other revenues approved by the county convention into the revolving fund, provided that funds in excess of the original appropriated amount shall be deposited into the general fund. The money in the fund shall be allowed to accumulate from year to year. The county treasurer shall have custody of all moneys in the fund, and shall pay out the same only upon order of the county commissioners. Such funds shall be expended only for the purposes for which the fund was created. III. The county convention may, at the time it establishes a county public safety revolving fund or at any time thereafter, place limitations on expenditures from the fund including, but not limited to, restrictions on the types of items or services that may be purchased from the fund. No amount may be expended from a revolving fund established hereunder for any item or service for which an appropriation has been specifically rejected by the county convention during the same year. IV. The provisions of this section shall not preclude the establishment of a county public safety revolving fund for any other purpose authorized by law.