S.D. Codified Laws § 10-27-5
If the party seeking relief asserts the invalidity of the tax, its application or its legal existence as a lien or claim against the property involved, as distinguished from irregularities in procedure no tender may be required as to any portion properly asserted to be invalid or void as a tax for any reason going to its base or legal existence. In all such cases, the court in the action or proceeding shall first determine the question of the legality or existence of any tax and, if necessary, to make proper assessment, calculation, and order as to the amount, if any, which should have been legally paid. All of this shall be determined as of the date when the assessment and levy was or should have been made, except that the due date of the tax shall be established as the first day of January next following the date when an assessment originally was or should have been made. The court shall enter its order directing the party seeking relief to deposit a sum with interest at the Category G rate of interest as established in § 54-3-16 from the date when the tax originally became or should have become due.
SDCL 10-27-5