N.H. Rev. Stat. § 282-A:48
Any interested party may appeal from a certifying officer's determination by filing an appeal to an appeal tribunal which must be received or, if filed by mail, postmarked within 14 calendar days after the determination was mailed to his last known address; provided that, if the commissioner finds sufficient grounds to justify or excuse a delay in filing an appeal, he may extend the time for filing the appeal.
RSA 282-A:48
1937, 178:1. 1939, 138:13. 1941, 103:21-23. RL 218:5. 1945, 138:11, 12. 1947, 59:14, 15. 1949, 185:7-10; 290:2. 1951, 36:2; 140:8; 142:7, 8. 1953, 209:4. RSA 282:5(6)(B). 1955, 71:1; 141:10, 11. 1957, 118:6. 1961, 88:10-16. 1965, 208:6, 7; 373:2. 1969, 460:8-10. 1971, 156:23; 539:16-19. 1973, 119:1; 589:5, 6. 1981, 403:3. 1985, 340:5. 1991, 311:5, eff. June 30, 1991.