S.D. Codified Laws § 26-2-6

In all cases other than those specified in §§ 26-2-4 and 26-2-5, the contract of a minor, if made while he is under the age of sixteen, may be disaffirmed by the minor himself, either before his majority or within one year's time afterwards; or in case of his death within that period, by his heirs or personal representatives; and, if the contract be made by the minor after he has reached the age of sixteen, it may be disaffirmed in like manner upon restoring the consideration to the party from whom it was received or paying its equivalent with interest.