A “lobbyist” is a person employed for consideration in a representative capacity to promote or oppose, directly or indirectly, any legislation pending or proposed before the general court, or to promote or oppose, directly or indirectly, any action by the governor, governor and council, or any state agency, where such action concerns legislation or contracts pending or proposed before the general court, any pending or proposed administrative rule, or the procurement of goods or services that are being or may be purchased by the state.

“Lobbyist” does not include a person who:

• Is employed to represent another only in an adjudicative proceeding or nonadjudicative process, other than a rulemaking proceeding or any process related to the purchasing of goods or services by the state, and who files an appearance with the authority conducting the matter; or
• Is an owner or employee, of a business seeking to do business with the state or communicating with an executive branch official or employee, a state agency, or an administrative official of the general court regarding goods or services that are being or may be purchased by the state.

N.H. Rev. Stat. Ann. § 15:1

Lobbyists are required to register as a lobbyist with the New Hampshire Secretary of State. Each registration must report the existence of a relationship between a single client and either a single lobbyist or a partnership, firm, or corporation with one or more partners, members, or employees of a firm acting as lobbyist. To register, a lobbyist must complete a Lobbyist Registration Form and pay a $50 fee for each reported client or employer. Registration must be renewed annually and expires on December 31st.

N.H. Rev. Stat. Ann. § 15:1
N.H. Rev. Stat. Ann. § 15:4

Each lobbyist must also file itemized statements (Addendums A, B, and C) of:

• All fees received from any lobbying client that are related, directly or indirectly, to lobbying, such as public advocacy, government relations, or public relations services including research, monitoring legislation, and related legal work;
• All expenditures made from lobbying fees, including by whom paid or to whom charged.
• Any honorarium or expense reimbursement or political contribution made by the lobbyist in his or her professional or personal capacity, on behalf of the lobbyist, the partnership, firm, or corporation or by the lobbyist on behalf of the client or employer or by a family member of the lobbyist.

Lobbyists must file these statements no later than the last Wednesday of each January, April, July, and October.

N.H. Rev. Stat. Ann. § 15:6

New Hampshire Secretary of State: Lobbyists Forms
http://sos.nh.gov/lobby.aspx