N.H. Rev. Stat. Ann. § 546-A:2

Every person whose income or other resources are more than sufficient to provide for his or her reasonable subsistence compatible with decency or health owes a duty to support or contribute to the support of the following persons when in need: his or her wife, husband, or child under the age of 18 or for as long as the department of health and human services has the authority to recover support for the child under Title IV of the Social Security Act.