S.C. Code § 12-37-2870
The distribution of the fee revenues required to be distributed pursuant to Section 12-37-2865 for each county must be determined on the ratio of total federal and state highway miles within each county during the preceding calendar year to the total federal and state highway miles within all counties of this State during the same preceding calendar year. The county must distribute the revenue from the payment-in-lieu of taxes received pursuant to this section within thirty days of its receipt to every governmental entity levying a property tax in the manner set forth below. For each governmental entity levying a property tax, the entire assessed value of the taxable property within its boundaries and the county area must be multiplied by the millage rate imposed by the governmental entity. That figure constitutes the numerator for that governmental entity. The total of the numerators for all property tax levying entities within the county area constitutes the denominator. The numerator for each governmental entity must be divided by the denominator. The resulting percentage must be multiplied by the fee revenue received pursuant to this section and that amount distributed to the general fund of the appropriate governmental entity. The distribution of taxes and fees paid must be made by the last day of the next month succeeding the month in which the taxes and fees were paid.
S.C. Code § 12-37-2870
2017 Act No. 40, Sections 8.L, 8.M, provide as follows:
"L. (1) Notwithstanding any provision to the contrary within this SECTION, a person who registers a vehicle for use in this State pursuant to Article 23, Chapter 37, Title 12, as amended by this act, must register his vehicle during calendar year 2019 and is required to pay the road fees calculated based on the fair market value of the vehicle as specified in Sections 12-37-2820 and 12-37-2850 at the time the vehicle's registration fees are paid.
"(2) Notwithstanding the provisions in Section 12-37-2865(B) and (C), as contained in this SECTION, to the contrary, during calendar year 2019, the first four hundred thousand dollars of fee revenue collected pursuant to Section 12-37-2865 must be retained by the Department of Motor Vehicles to defray programming costs.
"(3) The initial millage required by Section 12-37-2850 must be calculated on or before June 1, 2018.
"M. This SECTION takes effect January 1, 2019, except that the Department of Revenue, in consultation with the Revenue and Fiscal Affairs Office, shall calculate the millage to be used to calculate the road use fee provided in Section 12-37-2850 by July 1, 2018."