N.H. Rev. Stat. Ann. § 263:93

The commercial driver license shall expire on the licensee's birthdate in the fifth year following the issuance of such license. When applying for renewal of a commercial driver license, the applicant shall complete the application form as specified in RSA 263:90 and shall provide updated information and required certifications. If the applicant wishes to retain a hazardous materials endorsement, the written test for a hazardous materials endorsement shall be taken and passed.