(1) The county treasurer shall make diligent inquiry as to all persons in the county required to pay a license fee as provided in this part.
(2) Whenever the licenses are divided into classes, the county treasurer shall require each person to state, under oath or affirmation, the probable amount of business that the person, the firm of which the person is a member or for which the person is an agent or attorney, or the association or corporation of which the person is the president, secretary, or managing agent will do in the succeeding 3 months. The person, agent, president, secretary, or other officer shall procure a license from the county treasurer for the term desired and the proper class. In all cases in which an underestimate has been made by the party applying, the party making the underestimate or the company that the party represented is required to pay double the sum otherwise required for a license for the next quarter.