N.H. Rev. Stat. Ann. § 80:52-c

The governing body may authorize the municipality's treasurer or other appropriate municipal official to accept payment of local taxes, charges generated by the sale of utility services, or other fees or charges by use of a credit card, debit card, or such other means of electronic transaction as approved by the governing body. Any municipality may add to the amount due, in addition to any penalties and interest payable, a service charge for the acceptance of the credit card, debit card, or such other means of electronic transaction as approved by the governing body. The municipality, at the time of billing, shall disclose the amount of the service charge.