N.H. Rev. Stat. § 76:13
Interest at 8 percent per annum shall be charged upon all taxes except resident taxes, except as otherwise provided by statute, not paid on or before December 1 after their assessment, which shall be collected from that date with the taxes as incident thereto, except in the case where a tax bill sent to the taxpayer on or after November 2 and before April 1 of the following year interest shall not be charged until 30 days after the bills are mailed. Interest due in an amount up to $25 may be waived by the collector, with the approval and consent of the board of selectmen and the board of assessors, if in the collector's judgment the administrative and collection costs involved do not warrant collection of the amount due. The tax collector shall state on the tax bill the date from which interest will be charged and such date shall be determined by the day the collector sends out the last tax bill on the list. The collector shall notify the board of tax and land appeals in writing of the date on which the last tax bill was sent.
RSA 76:13
1860, 2373. 1861, 2491. GS 53:9. 1872, 42:1. GL 57:9. PS 59:8. PL 64 :11. RL 77:11. 1943, 55:1. 1949, 61:1. RSA 76:13. 1965, 81:1. 1969, 206:1. 1970, 30:1. 1973, 486:4; 544:8. 1977, 354:1. 1981, 465:14. 1989, 39:1. 1991, 54:1; 306:9. 2001, 63:1, eff. April 1, 2001. 2018, 282:1, eff. Apr. 1, 2019.