S.D. Codified Laws § 3-13-54
The board may promulgate rules pursuant to chapter 1-26 concerning the time and amount of compensation which may be deferred, the persons who may participate in the plan, the conditions of participation, the time and manner in which accumulated deferrals may be made available to a participant or beneficiary, the establishment of administrative changes, and participation by political subdivisions. Except pursuant to the provisions of an automatic enrollment feature established under subdivision 3-13-56(4), in no event may the accumulated deferred compensation become available to the participant prior to thirty days following the participant's separation from employment with a participating employer unless the participant is faced with an unforeseeable emergency as determined by the board, unless an in-service distribution of a small amount of funds is made, or unless a distribution is made to a participant who has been called to perform qualified military service for a period in excess of thirty days. If a participant returns to service with a participating employer within thirty days following separation from service, the accumulated deferred compensation is not available to the participant.
SDCL 3-13-54