N.H. Rev. Stat. Ann. § 235:39

When any county, town or city may have accepted the provisions of RSA 281, pursuant to RSA 281:7 and in which county, town or city there are spent state funds on any state aid or town aid highway or bridge project, the joint fund for such project may be charged that portion of premiums it pays for workers' compensation insurance which the commissioner of transportation determines to be the amount which should be allocated to such project.