Any county having a county transfer tax may provide for an exemption from the tax for an instrument of writing for residentially improved owner-occupied real property if the instrument of writing is accompanied by a statement under oath signed by each grantee or an agent of the grantee that: the grantee is an individual who has never owned in the State residential real property that has been the individual’s principal residence; and the residence will be occupied by the grantee as the grantee’s principal residence; or the grantee is a co-maker or guarantor of a purchase money mortgage or purchase money deed of trust as defined in § 12-108(i) of this article for the property; and the grantee will not occupy the residence as the co-maker’s or guarantor’s principal residence. A statement under subsection (a) of this section by an agent of a grantee shall state that the statement: is based on a diligent inquiry made by the agent with respect to the facts set forth in the statement; and is true to the best of the knowledge, information, and belief of the agent.