S.D. Codified Laws § 58-18-48
If an employer has an existing health benefit plan, the carrier shall accept for coverage under the health benefit plan new employees and the dependents of new employees, if the new employee had creditable coverage within the prior sixty-three days from the date the new employee is eligible for coverage. The coverage shall be issued without exclusionary riders. The carrier is not required to provide coverage for new employees or dependents who are late enrollees or who have not had creditable coverage within sixty-three days before applying for coverage. The exception allowing late enrollees to be excluded is limited to the time frames required by subdivisions 58-18-45(3) and (5). Policies may not exclude children, as set forth in subdivision 58-18-43(4), from the definition of eligible dependents. No person may be excluded from coverage based upon discriminatory criteria as defined by the director in rules promulgated pursuant to chapter 1-26.
SDCL 58-18-48