S.D. Codified Laws § 24-15A-19
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 consecutively, shall be considered as one conviction. Two or more sentences arising from different transactions for which the sentences are made to run consecutively shall be considered as separate convictions. For a person receiving two or more sentences which are made to run consecutively, time to serve to initial parole shall be calculated individually for each sentence then added to determine actual first parole date. In cases of different transactions, at least one occurring prior to July 1, 1996, and at least one occurring on or after July 1, 1996, time to initial parole shall be calculated by adding the time to serve to initial parole on transactions occurring on or after July 1, 1996, to the parole eligibility date of the transactions occurring prior to July 1, 1996, unless the subsequent transaction is a result of a crime committed as an inmate pursuant to § 24-15A-20.
In cases of different transactions, where at least one transaction has a discretionary parole date as a result of a parole revocation pursuant to § 24-15-24, § 24-15A-29, or as a result of noncompliance pursuant to § 24-15A-39, and at least one transaction has an initial parole date pursuant to § 24-15A-32, time to initial parole shall be calculated by adding the time to serve to parole on transactions with an initial parole date to the parole eligibility date on transactions with a discretionary date. Parole eligibility as used in this section is the date the inmate is next eligible for a parole hearing based on transactions with a discretionary date.
SDCL 24-15A-19