S.D. Codified Laws § 24-15A-18
In the determination of an inmate's initial parole date, two or more convictions arising from the same transaction, for which the sentences are made to run concurrently, shall be considered as one conviction. Two or more sentences arising from different transactions for which the sentences are made to run concurrently shall be considered as separate convictions. The first parole date shall be figured on the concurrent sentence with the longest time to serve to parole. If there are different transactions with at least one occurring prior to July 1, 1996, and at least one occurring on or after July 1, 1996, the inmate shall be subject to parole provisions effective at the time of the offense with the longest time to parole eligibility or initial parole.
SDCL 24-15A-18