S.D. Codified Laws § 10-46-2.1
For the privilege of using services in South Dakota, except those types of services exempted by § 10-46-17.3, there is imposed on the person using the service an excise tax equal to four and one-half percent of the value of the services at the time they are rendered. However, this tax may not be imposed on any service rendered by a related corporation as defined in subdivision 10-43-1(11) for use by a financial institution as defined in subdivision 10-43-1(4) or on any service rendered by a financial institution as defined in subdivision 10-43-1(4) for use by a related corporation as defined in subdivision 10-43-1(11). For the purposes of this section, the term related corporation includes a corporation which together with the financial institution is part of a controlled group of corporations as defined in 26 U.S.C. § 1563 as in effect on January 1, 1989, except that the eighty percent ownership requirements set forth in 26 U.S.C. § 563(a)(2)(A) for a brother-sister controlled group are reduced to fifty-one percent. For the purpose of this chapter, services rendered by an employee for the use of his employer are not taxable.
SDCL 10-46-2.1