S.C. Code Ann. § 5-41-170: Tax credit.

(A)(1) The amount of any credit allowed pursuant to this chapter is determined by multiplying the property tax value of the property, before the exemption provided in Section 12-37-250, by a fraction in which the numerator is the total estimated revenue allotted to the credit during the applicable fiscal year of the municipality, and the denominator is the total of all property tax value on property assessed pursuant to Section 12-43-220(c) in the municipality or portion thereof in which the sales and use tax authorized by this chapter is imposed, including the value exempted in Section 12-37-250.

(2) For purposes of this subsection, "property tax value" means the fair market value as it may be adjusted downward to reflect the limits imposed pursuant to Section 12-37-3140, in the municipality as of January first of the applicable property tax year.

(B) If there is any unused credit, then the unused funds must be used to provide a credit in the same manner as provided in subsection (A) over the next three property tax years.