S.C. Code Ann. § 12-43-225
(B) To be eligible for a subdivision lot discount, the final or conditional plat filed must contain at least ten building lots. The owner must apply for the discount by means of a written application to the assessor on or before May first of the year for which the discount is claimed. The value of each platted building lot is calculated: (1) by dividing the total number of platted building lots into the value of the entire parcel as undeveloped real property; and (2) as provided in Section 12-43-224 and the difference between the two calculations determined. The value of a lot as determined under Section 12-43-224 is reduced as follows:
For lots in plats filed in 2001, the value is reduced by thirty percent of the difference. For lots in plats filed in 2002, the value is reduced by sixty percent. For lots in plats filed after 2002, the value is reduced by one hundred percent of the difference.