The agricultural land transfer tax applies at the following rates: for a transfer of 20 acres or more of agricultural land, 5%; except as provided in item (3) of this subsection, for a transfer of less than 20 acres of agricultural land assessed for agricultural use or as unimproved agricultural land, 4%; or for a transfer of less than 20 acres of agricultural land assessed as improved agricultural land or agricultural land with site improvements, 3%. If an instrument of writing is subject to different rates of agricultural land transfer tax under subsection (a) of this section, the total agricultural land transfer tax due is computed separately for each portion of agricultural land to which a different rate applies. Except as provided by § 13–305(b)(2) or (c)(4) of this subtitle, the agricultural land transfer tax determined under subsection (a) or subsection (b) of this section is reduced by: 25% if property tax on the agricultural land was paid on the basis of any assessment other than the farm or agricultural use assessment under § 8–209 of this article for 1 full taxable year before a transfer; 50% if property tax on the agricultural land was paid on the basis of any assessment other than the farm or agricultural use assessment under § 8–209 of this article for 2 full consecutive taxable years before a transfer; and 65% if property tax on the agricultural land was paid on the basis of any assessment other than the farm or agricultural use assessment under § 8–209 of this article for 3 or more full consecutive taxable years before a transfer. Except as provided in paragraph (2) of this subsection, in addition to the agricultural land transfer tax, a surcharge in an amount equal to 25% of the tax determined under subsections (a) through (c) of this section is imposed on an instrument of writing that transfers title to agricultural land. The surcharge imposed under paragraph (1) of this subsection does not apply to an instrument of writing that transfers property of 2 acres or less to be improved to a child or grandchild of the owner. When determining the rate of the agricultural land transfer tax to be imposed under subsection (a) or (b) of this section, the amount of agricultural land transferred that is exempt from the tax in accordance with § 13–305 of this subtitle may not be included in the amount of agricultural land that is transferred.