SDCL § 10-23-14: Mistaken or wrongful sale of tax certificate--Refund to purchaser.

If a tax certificate is sold by mistake or wrongful act of the treasurer, the county shall refund the purchaser, the purchaser's heirs, assigns, or personal representatives the amount paid on the real property and any subsequent taxes paid to protect the tax certificate, with interest at the Category A rate of interest as established in § 54-3-16 from the date of the payment. The refund shall continue until paid or until notice is served by the treasurer, either personally or by registered or certified mail, upon the purchaser, the purchaser's heirs, assigns, or personal representatives, demanding that the tax certificate be surrendered for cancellation.