N.H. Rev. Stat. § 21-J:33

In addition to amounts due under this subdivision, penalties shall be imposed for failure to pay taxes when, and as, due as follows: I. If the failure to pay is not due to fraud, the penalty shall be equal to 10 percent of the amount of the nonpayment or underpayment. This penalty shall not be applied in any case in which the failure to pay was due to reasonable cause and not willful neglect of the taxpayer. II. If the failure to pay is due to fraud, the penalty shall be 50 percent of the amount of the nonpayment or underpayment. If a penalty is imposed under this paragraph, no addition to tax shall be imposed under this subdivision for the same nonpayment or underpayment. III. In the case of any failure to comply with the electronic payment requirements under RSA 21-J:3, XXI, a penalty shall be added to the amount of tax due equal to 5 percent of the amount of such tax not to exceed $5,000. This penalty is in addition to any other penalty that may be applicable and shall be assessed, collected, and paid in the same manner as taxes. The penalty in this paragraph shall not apply if failure to pay was due to reasonable cause and not willful neglect of the taxpayer.