S.D. Codified Laws § 43-32-6.1

Any deposit of money, the function of which is to secure the performance of a residential rental agreement or any part of such an agreement, shall be deemed to be a security deposit. A lessor of residential premises may not demand or receive a security deposit, however denominated, in an amount or value in excess of one month's rent except that a larger deposit may be agreed upon between the lessor and the lessee where special conditions pose a danger to maintenance of the premises.