South Dakota Codified Laws
Chapter 05A - County Wheel Tax
Section 32-5A-7 - Prorated tax if licensed for less than twelve months.

32-5A-7. Prorated tax if licensed for less than twelve months.
If a motor vehicle is licensed for a period of time of less than twelve months, any wheel tax imposed on such motor vehicle pursuant to this chapter shall be prorated on a monthly basis.

Source: SL 1994, ch 244, ยง4.