S.D. Codified Laws § 47-1A-704

Action required or permitted by this chapter to be taken at a shareholders' meeting may be taken without a meeting if the action is taken by all the shareholders entitled to vote on the action. The action shall be evidenced by one or more written consents describing the action taken, signed by all the shareholders entitled to vote on the action, and delivered to the corporation for inclusion in the minutes or filing with the corporate records. If not otherwise fixed under § 47-1A-703 or 47-1A-707 , the record date for determining shareholders entitled to take action without a meeting is the date the first shareholder signs the consent under this section. No written consent is effective to take the corporate action referred to therein unless written consents signed by all shareholders entitled to vote on the action are received by the corporation. A written consent may be revoked by a writing to that effect received by the corporation prior to receipt by the corporation of unrevoked written consents signed by all shareholders entitled to vote on the action. A consent signed under this section has the effect of a meeting vote and may be described as such in any document.

Source: SL 2005, ch 239, § 89.