S.C. Code § 12-37-2610
The tax year for licensed motor vehicles begins with the last day of the month in which a registration required by Section 56-3-110 is issued and ends on the last day of the month in which the registration expires or is due to expire. A registration may not be issued for motor vehicles until the ad valorem tax is paid for the year for which the registration is to be issued. Large commercial motor vehicles and buses, as defined in Section 12-37-2810, must pay road use fees pursuant to Article 23, Chapter 37, Title 12 in lieu of ad valorem property taxes. The provisions of this section do not apply to the transfer of motor vehicle registrations as specified in Section 12-37-2675 or to sales of motor vehicles by a licensed motor vehicle dealer. Notice of the sales must be furnished to the Department of Motor Vehicles by the dealer, along with other documents necessary for the registration and licensing of the vehicle concerned. The notice must be received by the Department of Motor Vehicles as a prerequisite to the registration and licensing of the vehicle and must include the name and address of the purchaser, the vehicle identification number, and the year and model of the vehicle. The notice must be an original and one copy, and the copy must be provided by the department to the auditor of the county in which the vehicle is taxable. All ad valorem taxes on a vehicle are due and payable one hundred twenty days from the date of purchase. The notice and the time in which to pay the tax applies to motor vehicles that are serviced and delivered by a licensed motor vehicle dealer for the benefit of an out-of-state dealer.
S.C. Code § 12-37-2610
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."